title: On the Secure Degrees of Freedom of Wireless X Networks

abstract:
  Previous work showed that the X network with M transmitters, N receivers has
MN/(M+N-1) degrees of freedom. In this work we study the degrees of freedom of
the X network with secrecy constraints, i.e. the X network where some/all
messages are confidential. We consider the $M \times N$ network where all
messages are secured and show that N(M-1)/(M+N-1) degrees of freedom can be
achieved. Secondly, we show that if messages from only M-1 transmitters are
confidential, then MN/(M+N-1) degrees of freedom can be achieved meaning that
there is no loss of degrees of freedom because of secrecy constraints. We also
consider the achievable secure degrees of freedom under a more conservative
secrecy constraint. We require that messages from any subset of transmitters
are secure even if other transmitters are compromised, i.e., messages from the
compromised transmitter are revealed to the unintended receivers. We also study
the achievable secure degrees of freedom of the K user Gaussian interference
channel under two different secrecy constraints where 1/2 secure degrees of
freedom per message can be achieved. The achievable scheme in all cases is
based on random binning combined with interference alignment.


title: Quark-nova remnants IV: Application to radio emitting AXP transients

abstract:
  (Abridged) XTE J1810-197 and 1E 1547.0-5408 are two transient AXPs exhibiting
radio emission with unusual properties. In addition, their spin down rates
during outburst show opposite trends, which so far has no explanation. Here, we
extend our quark-nova model for AXPs to include transient AXPs, in which the
outbursts are caused by transient accretion events from a Keplerian (iron-rich)
degenerate ring. For a ring with inner and outer radii of 23.5 km and 26.5 km,
respectively, our model gives a good fit to the observed X-ray outburst from
XTE J1810-197 and the behavior of temperature, luminosity, and area of the two
X-ray blackbodies with time. The two blackbodies in our model are related to a
heat front (i.e. Bohm diffusion front) propagating along the ring's surface and
an accretion hot spot on the quark star surface. Radio pulsations in our model
are caused by dissipation at the light cylinder of magnetic bubbles, produced
near the ring during the X-ray outburst. The delay between X-ray peak emission
and radio emission in our model is related to the propagation time of these
bubbles to the light cylinder. We predict a ~1 year and ~1 month delay for XTE
J1810-197 and 1E 1547.0-5408, respectively. The observed flat spectrum, erratic
pulse profile, and the pulse duration are all explained in our model as a
result of X-point reconnection events induced by the dissipation of the bubbles
at the light cylinder. The spin down rate of the central quark star can either
increase or decrease depending on how the radial drift velocity of the magnetic
islands changes with distance from the central star. We suggest an evolutionary
connection between transient AXPs and typical AXPs in our model.


title: Geometric Exponents, SLE and Logarithmic Minimal Models

abstract:
  In statistical mechanics, observables are usually related to local degrees of
freedom such as the Q < 4 distinct states of the Q-state Potts models or the
heights of the restricted solid-on-solid models. In the continuum scaling
limit, these models are described by rational conformal field theories, namely
the minimal models M(p,p') for suitable p, p'. More generally, as in stochastic
Loewner evolution (SLE_kappa), one can consider observables related to nonlocal
degrees of freedom such as paths or boundaries of clusters. This leads to
fractal dimensions or geometric exponents related to values of conformal
dimensions not found among the finite sets of values allowed by the rational
minimal models. Working in the context of a loop gas with loop fugacity beta =
-2 cos(4 pi/kappa), we use Monte Carlo simulations to measure the fractal
dimensions of various geometric objects such as paths and the generalizations
of cluster mass, cluster hull, external perimeter and red bonds. Specializing
to the case where the SLE parameter kappa = 4p'/p is rational with p < p', we
argue that the geometric exponents are related to conformal dimensions found in
the infinitely extended Kac tables of the logarithmic minimal models LM(p,p').
These theories describe lattice systems with nonlocal degrees of freedom. We
present results for critical dense polymers LM(1,2), critical percolation
LM(2,3), the logarithmic Ising model LM(3,4), the logarithmic tricritical Ising
model LM(4,5) as well as LM(3,5). Our results are compared with rigourous
results from SLE_kappa, with predictions from theoretical physics and with
other numerical experiments. Throughout, we emphasize the relationships between
SLE_kappa, geometric exponents and the conformal dimensions of the underlying
CFTs.

categories: cond-mat.stat-mech hep-th math-ph math.MP


title: Secure Wireless Communications via Cooperation

abstract:
  The feasibility of physical-layer-based security approaches for wireless
communications in the presence of one or more eavesdroppers is hampered by
channel conditions. In this paper, cooperation is investigated as an approach
to overcome this problem and improve the performance of secure communications.
In particular, a decode-and-forward (DF) based cooperative protocol is
considered, and the objective is to design the system for secrecy capacity
maximization or transmit power minimization. System design for the DF-based
cooperative protocol is first studied by assuming the availability of global
channel state information (CSI). For the case of one eavesdropper, an iterative
scheme is proposed to obtain the optimal solution for the problem of transmit
power minimization. For the case of multiple eavesdroppers, the problem of
secrecy capacity maximization or transmit power minimization is in general
intractable. Suboptimal system design is proposed by adding an additional
constraint, i.e., the complete nulling of signals at all eavesdroppers, which
yields simple closed-form solutions for the aforementioned two problems. Then,
the impact of imperfect CSI of eavesdroppers on system design is studied, in
which the ergodic secrecy capacity is of interest.


title:
The first measurement of the top quark mass at CDF II in the lepton+jets
  and dilepton channels simultaneously

abstract:
  We present a measurement of the mass of the top quark using data
corresponding to an integrated luminosity of 1.9fb^-1 of ppbar collisions
collected at sqrt{s}=1.96 TeV with the CDF II detector at Fermilab's Tevatron.
This is the first measurement of the top quark mass using top-antitop pair
candidate events in the lepton + jets and dilepton decay channels
simultaneously. We reconstruct two observables in each channel and use a
non-parametric kernel density estimation technique to derive two-dimensional
probability density functions from simulated signal and background samples. The
observables are the top quark mass and the invariant mass of two jets from the
W decay in the lepton + jets channel, and the top quark mass and the scalar sum
of transverse energy of the event in the dilepton channel. We perform a
simultaneous fit for the top quark mass and the jet energy scale, which is
constrained in situ by the hadronic W boson mass. Using 332 lepton + jets
candidate events and 144 dilepton candidate events, we measure the top quark
mass to be mtop=171.9 +/- 1.7 (stat. + JES) +/- 1.1 (syst.) GeV/c^2 = 171.9 +/-
2.0 GeV/c^2.


title: Measurement of CP Observables in B to D0 K Decays at CDF

abstract:
  This paper describes the determination of the direct CP observables R_cp and
A_cp, related to the CKM angle gamma, using B- to D0 K- decays in 1.0 inverse
fb of data collected with the CDF II detector. This is the first measurement of
these CP observables made at a hadron collider in this decay mode. The results
presented are consistent with the measurements of these quantities made by the
Belle and BABAR collaborations.


abstract:
  We further develop the theory of inducing $W$-graphs worked out by Howlett
and Yin in \cite{HY1}, \cite{HY2}, focusing on the case $W = \S_n$. Our main
application is to give two $W$-graph versions of tensoring with the $\S_n$
defining representation $V$, one being $\H \tsr_{\H_J} -$ for $\H, \H_J$ the
Hecke algebras of $\S_n, \S_{n-1}$ and the other $(\pH \tsr_{\H} -)_1$, where
$\pH$ is a subalgebra of the extended affine Hecke algebra and the subscript
signifies taking the degree 1 part. We look at the corresponding $W$-graph
versions of the projection $V \tsr V \tsr - \to S^2 V \tsr -$. This does not
send canonical basis elements to canonical basis elements, but we show that it
approximates doing so as the Hecke algebra parameter $\u \to 0$. We make this
approximation combinatorially explicit by determining it on cells. Also of
interest is a combinatorial conjecture stating the restriction of $\H$ to
$\H_J$ is "weakly multiplicity-free" for $|J| = n-1$, and a partial
determination of the map $\H \tsr_{\H_J} \H \xrightarrow{\counit} \H$ on
canonical basis elements, where $\counit$ is the counit of adjunction.


title: Partonic State and Single Transverse Spin Asymmetry in Drell-Yan Process

abstract:
  Single transverse-spin asymmetries have been studied intensively both in
experiment and theory. Theoretically, two factorization approaches have been
proposed. One is by using transverse-momentum-dependent factorization and the
asymmetry comes from the so called Sivers function. Another is by using
collinear factorization where the nonperturbative effect is parameterized by a
twist-3 hadronic matrix element. However, the factorized formulas for the
asymmetries in the two approaches are derived at hadron level formally by
diagram expansion, where one works with various parton density matrices of
hadrons. If the two factorizations hold, they should also hold at parton level.
We examine this for Drell-Yan processes by replacing hadrons with partons. By
calculating the asymmetry, Sivers function and the twist-3 matrix element at
nontrivial leading order of $\alpha_s$, we find that we can reproduce the
result of the transverse-momentum-dependent factorization. But we can only
verify the result of the collinear factorization partly. Two formally derived
relations between Sivers function and the twist-3 matrix element are also
examined with negative results.


title: Control software analysis, Part I Open-loop properties

abstract:
  As the digital world enters further into everyday life, questions are raised
about the increasing challenges brought by the interaction of real-time
software with physical devices. Many accidents and incidents encountered in
areas as diverse as medical systems, transportation systems or weapon systems
are ultimately attributed to "software failures". Since real-time software that
interacts with physical systems might as well be called control software, the
long litany of accidents due to real-time software failures might be taken as
an equally long list of opportunities for control systems engineering. In this
paper, we are interested only in run-time errors in those pieces of software
that are a direct implementation of control system specifications: For
well-defined and well-understood control architectures such as those present in
standard textbooks on digital control systems, the current state of theoretical
computer science is well-equipped enough to address and analyze control
algorithms. It appears that a central element to these analyses is Lyapunov
stability theory, which translate into invariant theory in computer
implementations.


title:
The influence of quark energy loss on extracting nuclear sea quark
  distribution from nuclear Drell-Yan experimental data

abstract:
  By means of two typical kinds of quark energy loss parametrization and the
nuclear parton distributions determined only with lepton-nuclear deep inelastic
scattering experimental data, a leading order analysis are performed on the
proton-induced Drell-Yan differential cross section ratios of tungsten versus
deuterium as a function of the quark momentum fraction in the beam proton and
target nuclei. It is found that the theoretical results with quark energy loss
are in good agreement with the experimental data. The quark energy loss effect
produce approximately 3% to 11% suppression on the Drell-Yan differential cross
section ratios $R_{W/D}$ in the range $0.05\leq x_2\leq0.3$. The application of
nuclear Drell-Yan data with heavy targets is remarkably subject to difficulty
in the constraints of the nuclear sea-quark distribution.


title:
Reduction of the Number of Quantifiers in Real Analysis through
  Infinitesimals (Master Thesis, Mathematics Department, California Polytechnic
  State University, San Luis Obispo)

abstract:
  We construct the non-standard complex (and real) numbers using the ultrapower
method in the spirit of Cauchy's construction of the real numbers. We show that
the non-standard complex numbers are a non-archimedean, algebraically closed
field, and that the non-standard real numbers are a totally ordered,
real-closed, non-archimedean field. We explore the various types of
non-standard numbers, and develop the non-standard completeness results
(Saturation Principle, Supremum Completeness of Bounded Internal Sets, etc) for
$\starr$. We give non-standard characterizations for such usual topological
objects as open, closed, bounded, and compact sets in terms of monads. We also
consider such traditional topics of real analysis as limits, continuity,
uniform continuity, convergence, uniform convergence, etc. in a non-standard
setting. In both topology and real analysis we reduce (and in some cases
eliminate) the number of quantifiers in the non-standard setting.


title:
On Lagrangian formulations for mixed-symmetry HS fields on AdS spaces
  within BFV-BRST approach

abstract:
  The key aspects of a gauge-invariant Lagrangian description of massive and
massless half-integer higher-spin fields in AdS spaces with a two-row Young
tableaux $Y(s_1,s_2)$ are presented in an unconstrained description, as well as
in off-shell formulations with algebraic constraints, on the basis of BFV-BRST
operators for non-linear operator superalgebras, encoding the initial
conditions realized by constraints in a Fock space and extracting the
higher-spin fields from unitary representations of the AdS group.


title:
Doping evoluton of antiferromagnetic order and structural distortion in
  LaFeAsO$_{1-x}$F$_x$

abstract:
  We use neutron scattering to study the structural distortion and
antiferromagnetic (AFM) order in LaFeAsO$_{1-x}$F$_{x}$ as the system is doped
with fluorine (F) to induce superconductivity. In the undoped state, LaFeAsO
exhibits a structural distortion, changing the symmetry from tetragonal (space
group $P4/nmm$) to orthorhombic (space group $Cmma$) at 155 K, and then
followed by an AFM order at 137 K. Doping the system with F gradually decreases
the structural distortion temperature, but suppresses the long range AFM order
before the emergence of superconductivity. Therefore, while superconductivity
in these Fe oxypnictides can survive in either the tetragonal or the
orthorhombic crystal structure, it competes directly with static AFM order.


title: EMP and linear Schrodinger models for a conformally Bianchi I cosmology

abstract:
  Using a conformal version of the Bianchi I metric and a perfect fluid
energy-momentum tensor, we show that the resulting Einstein field equations are
equivalent to a generalized Ermakov-Milne-Pinney equation. Using a
transformation analogous to the known correspondence between the classical EMP
and a linear Schr\"odinger equation, we then construct the linear Schr\"odinger
formulation for this cosmological model. Also, a note is included to show the
extra term that arises when the energy-momentum tensor is taken to include a
second term in addition to the scalar field.


title:
Are Y(4260) and {\rm Z$_2^{+}$(4250)} ${\rm D_1D}$ or ${\rm D_0D^{*}}$
  Hadronic Molecules?

abstract:
  In this work, we have investigated whether Y(4260) and ${\rm Z^{+}_2(4250)}$
could be ${\rm D_1D}$ or ${\rm D_0D^{*}}$ molecules in the framework of meson
exchange model. The off-diagonal interaction induced by $\pi$ exchange plays a
dominant role. The $\sigma$ exchange has been taken into account, which leads
to diagonal interaction. The contribution of $\sigma$ exchange is not favorable
to the formation of molecular state ${\rm with I^{G}(J^{PC})=0^{-}(1^{--})}$,
however, it is beneficial to the binding of molecule ${\rm with
I^{G}(J^{P})=1^{-}(1^{-})}$. Light vector meson exchange leads to diagonal
interaction as well. For ${\rm Z^{+}_2(4250)}$, the contribution from $\rho$
and $\omega$ exchange almost cancels each other. For the currently allowed
values of the effective coupling constants and a reasonable cutoff $\Lambda$ in
the range 1-2 GeV, We find that Y(4260) could be accommodated as a ${\rm D_1D}$
and ${\rm D_0D^{*}}$ molecule, whereas the interpretation of ${\rm
Z^{+}_2(4250)}$ as a ${\rm D_1D}$ or ${\rm D_0D^{*}}$ molecule is disfavored.
The bottom analog of Y(4260) and ${\rm Z^{+}_2(4250)}$ may exist, and the most
promising channels to discovery them are $\pi^{+}\pi^{-}\Upsilon$ and
$\pi^{+}\chi_{b1}$ respectively.


title: Modified (A)dS Schwarzschild black holes in Rainbow spacetime

abstract:
  A modified (Anti-)de Sitter Schwarzschild black hole solution is presented in
the framework of rainbow gravity with a cosmological constant. Its
thermodynamical properties are investigated. In general the temperature of
modified black holes is dependent on the energy of probes which take the
measurement. However, a notion of intrinsic temperature can be introduced by
identifying these probes with radiation particles emitted from black holes. It
is interesting to find that the Hawking temperature of this sort of black holes
can be reproduced by employing the extended uncertainty principle and modified
dispersion relations to the ordinary (A)dS Schwarzschild black holes.


title: Spectral evidence for jets from Accreting Millisecond X-ray Pulsars

abstract:
  Transient radio emission from X-ray binaries is associated with synchrotron
emission from collimated jets that escape the system, and accreting millisecond
X-ray pulsars (AMXPs) are no exception. Although jets from black hole X-ray
binaries are well-studied, those from neutron star systems appear much fainter,
for reasons yet uncertain. Jets are usually undetectable at higher frequencies
because of the relative brightness of other components such as the accretion
disc. AMXPs generally have small orbital separations compared with other X-ray
binaries and as such their discs are relatively faint. Here, I present data
that imply jets in fact dominate the radio-to-optical spectrum of outbursting
AMXPs. They therefore may provide the best opportunity to study the behaviour
of jets produced by accreting neutron stars, and compare them to those produced
by black hole systems.


title: On Fan Raspaud Conjecture

abstract:
  A conjecture of Fan and Raspaud [3] asserts that every bridgeless cubic graph
con-tains three perfect matchings with empty intersection. Kaiser and Raspaud
[6] sug-gested a possible approach to this problem based on the concept of a
balanced join in an embedded graph. We give here some new results concerning
this conjecture and prove that a minimum counterexample must have at least 32
vertices.


title: On normal odd partitions in cubic graphs

abstract:
  A normal partition of the edges of a cubic graph is a partition into trails
(no repeated edge) such that each vertex is the end vertex of exactly one trail
of the partition. We investigate this notion and give some results and
problems.


title: Lawn tennis balls, Rolling friction experiment and Trouton viscosity

abstract:
  We took three lawn tennis balls arbitrarily. One was moderately old, one was
old and another was new. Fabricating a conveyor belt set-up we have measured
rolling friction coefficients, $\mu_{r}$, of the three balls as a function of
their angular velocities, $\omega_{ball}$. In all the three cases, plotting the
results and using linear fits, we have obtained relations of the form $\mu_{r}=
k_{rol} \omega_{ball}$ and have deduced the proportionality constant $k_{rol}$.
Moreover, core of a lawn tennis ball is made of vulcanised India-rubber. Using
the known values of Young modulus and shear viscosity of vulcanised
India-rubbers in the theoretical formula for $k_{rol}$, we estimate $k_{rol}$s
for the cores made of vulcanised India-rubbers, assuming Trouton ratio as
three. The experimental results for the balls and the semi-theoretical
estimates for the cores, of $k_{rol}$, are of the same order of magnitudes.


title: Stochastic solutions of a class of Higher order Cauchy problems in $\rd$

abstract:
  We study solutions of a class of higher order partial differential equations
in bounded domains. These partial differential equations appeared first time in
the papers of Allouba and Zheng \cite{allouba1}, Baeumer, Meerschaert and Nane
\cite{bmn-07}, Meerschaert, Nane and Vellaisamy \cite{MNV}, and Nane
\cite{nane-h}. We express the solutions by subordinating a killed Markov
process by a hitting time of a stable subordinator of index $0<\beta <1$, or by
the absolute value of a symmetric $\alpha$-stable process with $0<\alpha\leq
2$, independent of the Markov process. In some special cases we represent the
solutions by running composition of $k$ independent Brownian motions, called
$k$-iterated Brownian motion for an integer $k\geq 2$. We make use of a
connection between fractional-time diffusions and higher order partial
differential equations established first by Allouba and Zheng \cite{allouba1}
and later extended in several directions by Baeumer, Meerschaert and Nane
\cite{bmn-07}.


title:
Superconductivity and Pseudogap in Quasi-Two-Dimensional Metals around
  the Antiferromagnetic Quantum Critical Point

abstract:
  Spin fluctuations (SF) and SF-mediated superconductivity (SC) in
quasi-two-dimensional metals around the antiferrromagnetic (AF) quantum
critical point (QCP) are investigated by using the self-consistent
renormalization theory for SF and the strong coupling theory for SC. We
introduce a parameter y0 as a measure for the distance from the AFQCP which is
approximately proportional to (x-xc), x being the electron (e) or hole (h)
doping concentration to the half-filled band and xc being the value at the
AFQCP. We present phase diagrams in the T-y0 plane including contour maps of
the AF correlation length and AF and SC transition temperatures TN and Tc,
respectively. The Tc curve is dome-shaped with a maximum at around the AFQCP.
The calculated one-electron spectral density shows a pseudogap in the
high-density-of-states region near (pi,0) below around a certain temperature T*
and gives a contour map at the Fermi energy reminiscent of the Fermi arc. These
results are discussed in comparison with e- and h-doped high-Tc cuprates.


title: Q-curvature flow with indefinite nonlinearity

abstract:
  In this note, we study Q-curvature flow on $S^4$ with indefinite
nonlinearity. Our result is that the prescribed Q-curvature problem on $S^4$
has a solution provided the prescribed Q-curvature $f$ has its positive part,
which possesses non-degenerate critical points such that $\Delta_{S^4} f\not=0$
at the saddle points and an extra condition such as a nontrivial degree
counting condition.


title:
Generation of Nano-Catalyst Particles by Spinodal Nano-Decomposition in
  Perovskite

abstract:
  A new mechanism of nano-catalyst generation based on the spinodal
nano-decomposition in self-regenerating perovskite catalysts for
automotive-emissions control is proposed. To demonstrate existence of the
spinodal nano-decomposition in real perovskite catalysts, we performed
first-principles calculations to evaluate the free energy of
La(Fe$_{1-x}$Pd$_x$)O$_3$ and La(Fe$_{1-x}$Rh$_x$)O$_3$. The result indicates
appearance of a spinodal region in the phase diagram of each material.
Formation of nano-catalyst particles in the perovskite host matrix is crucial
for the self-regeneration of perovskite catalyst. Based on the spinodal
nano-decomposition model, possible materials are designed for new three-way
catalyst with no contents of precious metal.


title: Aspects of locally covariant quantum field theory

abstract:
  This thesis considers various aspects of locally covariant quantum field
theory (LCQFT; see Brunetti et al., Commun.Math.Phys. 237 (2003), 31-68), a
mathematical framework to describe axiomatic quantum field theories in curved
spacetimes. New results include: a philosophical interpretation of certain
aspects of this framework in terms of modal logic; a proof that the truncated
n-point functions of any Hadamard state of the free real scalar field are
smooth, except for n=2; a description of he free Dirac field in a
representation independent way, showing that the theory is determined entirely
by the relations between the adjoint map, the charge conjugation map and the
Dirac operator; a proof that the relative Cauchy evolution of the free Dirac
field is related to its stress-energy-momentum tensor in the same way as for
the free real scalar field (cf. loc.cit.); several results on the
Reeh-Schlieder property in LCQFT, including but not limited to those of our
earlier paper; a new and elegant approach to wave front sets of Banach
space-valued distributions, which allows easy proofs and extensions of results
in the literature.


title: Optimisation of future long baseline neutrino experiments

abstract:
  The aim of this talk is to review near and far future long baseline neutrino
experiments as superbeams, beta-Beams and neutrino factories, comparing their
sensitivities to the unknown parameters in the neutrino oscillation sector. We
focus on the extraction of the neutrino mass hierarchy, exploring alternatives
to the commonly used neutrino-antineutrino comparison. Special attention to a
new concept of neutrino factory design, the low energy neutrino factory, is
given.


title: Noise induced Hopf bifurcation

abstract:
  We consider effect of stochastic sources upon self-organization process being
initiated with creation of the limit cycle induced by the Hopf bifurcation.
General relations obtained are applied to the stochastic Lorenz system to show
that departure from equilibrium steady state can destroy the limit cycle in
dependence of relation between characteristic scales of temporal variation of
principle variables. Noise induced resonance related to the limit cycle is
found to appear if the fastest variations displays a principle variable, which
is coupled with two different degrees of freedom or more.


title: Towards a Theory of Entropy Production in the Little and Big Bang

abstract:
  We propose a broadly applicable formalism for the description of coarse
grained entropy production in quantum mechanical processes. Our formalism is
based on the Husimi transform of the quantum state, which encodes the notion
that information about any quantum state is limited by the experimental
resolution. We show in two analytically tractable cases (the decay of an
unstable vacuum state and reheating after cosmic inflation) that the growth
rate of the Wehrl entropy associated with the Husimi function approaches the
classical Kolmogorov-Sinai entropy. We also discuss various possible
applications of our formalism, including the production of entropy in the early
stages of a relativistic heavy ion collision.


title:
Splitting the Wino Multiplet by Higher-Dimensional Operators in Anomaly
  Mediation

abstract:
  In a class of AMSB models, the splitting in the Wino multiplet turns out to
be very small, such as the often-quoted 170 MeV in minimal AMSB, which
originates from MSSM loops. Such a small mass gap is potentially a window into
higher scale physics, as it may be sensitive to higher-dimensional operators.
We show that still within AMSB one can get a much larger splitting in the Wino
multiplet--a few GeV--if the scale of the new physics is comparable to the
gravitino mass (which is indeed often the scale of new physics in anomaly
mediation).


title: Information propagation through quantum chains with fluctuating disorder

abstract:
  We investigate the propagation of information through one-dimensional quantum
chains in fluctuating external fields. We find that information propagation is
suppressed, but in a quite different way compared to the situation with static
disorder. We study two settings: (i) a general model where an unobservable
fluctuating field acts as a source of decoherence; (ii) the XX model with both
observable and unobservable fluctuating fields. In the first setting we
establish a noise threshold below which information can propagate ballistically
and above which information is localised. In the second setting we find
localisation for all levels of unobservable noise, whilst an observable field
can yield diffusive propagation of information.


title: Relevance Feedback in Conceptual Image Retrieval: A User Evaluation

abstract:
  The Visual Object Information Retrieval (VOIR) system described in this paper
implements an image retrieval approach that combines two layers, the conceptual
and the visual layer. It uses terms from a textual thesaurus to represent the
conceptual information and also works with image regions, the visual
information. The terms are related with the image regions through a weighted
association enabling the execution of concept-level queries. VOIR uses
region-based relevance feedback to improve the quality of the results in each
query session and to discover new associations between text and image. This
paper describes a user-centred and task-oriented comparative evaluation of VOIR
which was undertaken considering three distinct versions of VOIR: a full-fledge
version; one supporting relevance feedback only at image level; and a third
version not supporting relevance feedback at all. The evaluation performed
showed the usefulness of region based relevance feedback in the context of VOIR
prototype.


title: Non-Standard Interaction Effects at Reactor Neutrino Experiments

abstract:
  We study non-standard interactions (NSIs) at reactor neutrino experiments,
and in particular, the mimicking effects on \theta_13. We present generic
formulas for oscillation probabilities including NSIs from sources and
detectors. Instructive mappings between the fundamental leptonic mixing
parameters and the effective leptonic mixing parameters are established. In
addition, NSI corrections to the mixing angles \theta_13 and \theta_12 are
discussed in detailed. Finally, we show that, even for a vanishing \theta_13,
an oscillation phenomenon may still be observed in future short baseline
reactor neutrino experiments, such as Double Chooz and Daya Bay, due to the
existences of NSIs.


title: Schwinger Bosons Approaches to Quantum Antiferromagnetism

abstract:
  These lectures review the large N Schwinger Bosons Mean Field approach to the
quantum Heisenberg model. The method applies to ordered and disordered phases
in all dimensions, at zero and at finite temperature. Extension to frustrated
models is explained. An example for an experimentally useful application, is
the temperature dependent staggered magnetization of the layered
antiferromagnet.


title:
Secant varieties of Segre-Veronese varieties P^m x P^n embedded by
  O(1,2)

abstract:
  Let $X_{m,n}$ be the Segre-Veronese variety $\mathbb{P}^m \times
\mathbb{P}^n$ embedded by the morphism given by $\mathcal{O}(1,2)$. In this
paper, we provide two functions $\underline{s}(m,n)\le \bar{s}(m,n)$ such that
the $s^{\mathrm{th}}$ secant variety of $X_{m,n}$ has the expected dimension if
$s \leq \underline{s}(m,n)$ or $ \bar{s}(m,n) \leq s$. We also present a
conjecturally complete list of defective secant varieties of such
Segre-Veronese varieties.


title:
The Back and Forth Nudging algorithm for data assimilation problems:
  theoretical results on transport equations

abstract:
  In this paper, we consider the back and forth nudging algorithm that has been
introduced for data assimilation purposes. It consists of iteratively and
alternately solving forward and backward in time the model equation, with a
feedback term to the observations. We consider the case of 1-dimensional
transport equations, either viscous or inviscid, linear or not (B\"urgers'
equation). Our aim is to prove some theoretical results on the convergence, and
convergence properties, of this algorithm. We show that for non viscous
equations (both linear transport and Burgers), the convergence of the algorithm
holds under observability conditions. Convergence can also be proven for
viscous linear transport equations under some strong hypothesis, but not for
viscous Burgers' equation. Moreover, the convergence rate is always exponential
in time. We also notice that the forward and backward system of equations is
well posed when no nudging term is considered.


title: M\'acajov\'a and \v{S}koviera Conjecture on Cubic Graphs

abstract:
  A conjecture of M\'a\u{c}ajov\'a and \u{S}koviera asserts that every
bridgeless cubic graph has two perfect matchings whose intersection does not
contain any odd edge cut. We prove this conjecture for graphs with few vertices
and we give a stronger result for traceable graphs.


title: Folding 3-noncrossing RNA pseudoknot structures

abstract:
  In this paper we present a selfcontained analysis and description of the
novel {\it ab initio} folding algorithm {\sf cross}, which generates the
minimum free energy (mfe), 3-noncrossing, $\sigma$-canonical RNA structure.
Here an RNA structure is 3-noncrossing if it does not contain more than three
mutually crossing arcs and $\sigma$-canonical, if each of its stacks has size
greater or equal than $\sigma$. Our notion of mfe-structure is based on a
specific concept of pseudoknots and respective loop-based energy parameters.
The algorithm decomposes into three parts: the first is the inductive
construction of motifs and shadows, the second is the generation of the
skeleta-trees rooted in irreducible shadows and the third is the saturation of
skeleta via context dependent dynamic programming routines.


title: Scaling of 1/f noise in tunable break-junctions

abstract:
  We have studied the $1/f$ voltage noise of gold nano-contacts in
electromigrated and mechanically controlled break-junctions having resistance
values $R$ that can be tuned from 10 $\Omega$ (many channels) to 10 k$\Omega$
(single atom contact). The noise is caused by resistance fluctuations as
evidenced by the $S_V\propto V^2$ dependence of the power spectral density
$S_V$ on the applied DC voltage $V$. As a function of $R$ the normalized noise
$S_V/V^2$ shows a pronounced cross-over from $\propto R^3$ for low-ohmic
junctions to $\propto R^{1.5}$ for high-ohmic ones. The measured powers of 3
and 1.5 are in agreement with $1/f$-noise generated in the bulk and reflect the
transition from diffusive to ballistic transport.


title: Monopole Floer homology for rational homology 3-spheres

abstract:
  We give a new construction of monopole Floer homology for spin-c rational
homology 3-spheres. As applications we define two invariants of certain smooth
compact 4-manifolds with b_1=1 and b^+=0.


title: Magnetic Charge of the Stark States of Hydrogen Atoms

abstract:
  It is conjectured that Stark states of excited hydrogen atom posses magnetic
charge for which the quantum mechanical operator is $${\cal G}_{op} = {e\over
\hbar} (\vec\sigma\cdot\vec A)$$ where $\vec A$ is the Runge-Lenz vector. The
expectation value $g$ of this operator for Stark states is found to be $$ g =
e(n_1-n_2)$$ which obeys a Dirac-Saha type quantization formula $${eg\over c} =
(n_1-n_2)\alpha$$ where $\alpha$ is the fine structure constant and $n_1$ and
$n_2$ are parabolic quantum numbers. An experimental arrangement is outlined to
test this conjecture.


title:
Phases of the Dirac determinant, Abelian Chern-Simons terms and Berry's
  phases in the field theoretic description of graphene

abstract:
  This talk presents a study of massless relativistic Dirac fields in three
Euclidean dimensions, at finite temperature and density, in the presence of a
uniform electromagnetic background. Apart from explaining the behavior of
Hall's conductivity for graphene, our results show a direct relationship
between the selection of a phase for the Dirac determinant and the generation
(or lack thereof) of Berry's phases and Chern-Simons terms.

categories: hep-th cond-mat.mes-hall math-ph math.MP


title: On the inverse problem of calculus of variations

abstract:
  We show that given an ordinary differential equation of order four, it may be
possible to determine a Lagrangian if the third derivative is absent (or
eliminated) from the equation. This represents a subcase of Fels'conditions [M.
E. Fels, The inverse problem of the calculus of variations for scalar
fourth-order ordinary differential equations, Trans. Amer. Math. Soc. 348
(1996) 5007-5029] which ensure the existence and uniqueness of the Lagrangian
in the case of a fourth-order equation. The key is the Jacobi last multiplier
as in the case of a second-order equation. Two equations from a Number Theory
paper by Hall, one of second and one of fourth order, will be used to exemplify
the method. The known link between Jacobi last multiplier and Lie symmetries is
also exploited. Finally the Lagrangian of two fourth-order equations drawn from
Physics are determined with the same method.


title:
Estimation of Higher Order Moments for Compound Models of Clutter by
  Mellin Transform

abstract:
  The compound models of clutter statistics are found suitable to describe the
nonstationary nature of radar backscattering from high-resolution observations.
In this letter, we show that the properties of Mellin transform can be utilized
to generate higher order moments of simple and compound models of clutter
statistics in a compact manner


title: Quantum States and Measures on the Spectral Presheaf

abstract:
  After a brief introduction to the spectral presheaf, which serves as an
analogue of state space in the topos approach to quantum theory, we show that
every state of the von Neumann algebra of physical quantities of a quantum
system determines a certain measure on the spectral presheaf of the system. The
so-called clopen subobjects of the spectral presheaf play the role of
measurable sets. Measures on the spectral presheaf can be characterised
abstractly, and the main result is that every abstract measure induces a unique
state of the von Neumann algebra. Finally, we show how quantum-theoretical
expectation values can be calculated from measures associated to quantum
states.


title:
Feshbach projection-operator formalism to resonance scattering on
  Bargmann-type potentials

abstract:
  The projection-operator formalism of Feshbach is applied to resonance
scattering in a single-channel case. The method is based on the division of the
full function space into two segments, internal (localized) and external
(infinitely extended). The spectroscopic information on the resonances is
obtained from the non-Hermitian effective Hamilton operator $H_{\rm eff}$
appearing in the internal part due to the coupling to the external part. As
well known, additional so-called cut-off poles of the $S$-matrix appear,
generally, due to the truncation of the potential. We study the question of
spurious $S$ matrix poles in the framework of the Feshbach formalism. The
numerical analysis is performed for exactly solvable potentials with a finite
number of resonance states. These potentials represent a generalization of
Bargmann-type potentials to accept resonance states. Our calculations
demonstrate that the poles of the $S$ matrix obtained by using the Feshbach
projection-operator formalism coincide with both the complex energies of the
physical resonances and the cut-off poles of the $S$-matrix.


title: Groups acting on manifolds: around the Zimmer program

abstract:
  This paper is a survey on the {\em Zimmer program}. In it's broadest form,
this program seeks an understanding of actions of large groups on compact
manifolds. The goals of this survey are $(1)$ to put in context the original
questions and conjectures of Zimmer and Gromov that motivated the program,
$(2)$ to indicate the current state of the art on as many of these conjectures
and questions as possible and $(3)$ to indicate a wide variety of open problems
and directions of research.


title:
Spectral and Dynamical Properties in Classes of Sparse Networks with
  Mesoscopic Inhomogeneities

abstract:
  We study structure, eigenvalue spectra and diffusion dynamics in a wide class
of networks with subgraphs (modules) at mesoscopic scale. The networks are
grown within the model with three parameters controlling the number of modules,
their internal structure as scale-free and correlated subgraphs, and the
topology of connecting network. Within the exhaustive spectral analysis for
both the adjacency matrix and the normalized Laplacian matrix we identify the
spectral properties which characterize the mesoscopic structure of sparse
cyclic graphs and trees. The minimally connected nodes, clustering, and the
average connectivity affect the central part of the spectrum. The number of
distinct modules leads to an extra peak at the lower part of the Laplacian
spectrum in cyclic graphs. Such a peak does not occur in the case of
topologically distinct tree-subgraphs connected on a tree. Whereas the
associated eigenvectors remain localized on the subgraphs both in trees and
cyclic graphs. We also find a characteristic pattern of periodic localization
along the chains on the tree for the eigenvector components associated with the
largest eigenvalue equal 2 of the Laplacian. We corroborate the results with
simulations of the random walk on several types of networks. Our results for
the distribution of return-time of the walk to the origin (autocorrelator)
agree well with recent analytical solution for trees, and it appear to be
independent on their mesoscopic and global structure. For the cyclic graphs we
find new results with twice larger stretching exponent of the tail of the
distribution, which is virtually independent on the size of cycles. The
modularity and clustering contribute to a power-law decay at short return
times.


title:
Point-occurrence self-similarity in crackling-noise systems and in other
  complex systems

abstract:
  It has been recently found that a number of systems displaying crackling
noise also show a remarkable behavior regarding the temporal occurrence of
successive events versus their size: a scaling law for the probability
distributions of waiting times as a function of a minimum size is fulfilled,
signaling the existence on those systems of self-similarity in time-size. This
property is also present in some non-crackling systems. Here, the uncommon
character of the scaling law is illustrated with simple marked renewal
processes, built by definition with no correlations. Whereas processes with a
finite mean waiting time do not fulfill a scaling law in general and tend
towards a Poisson process in the limit of very high sizes, processes without a
finite mean tend to another class of distributions, characterized by double
power-law waiting-time densities. This is somehow reminiscent of the
generalized central limit theorem. A model with short-range correlations is not
able to escape from the attraction of those limit distributions. A discussion
on open problems in the modeling of these properties is provided.


title: Energy-momentum/Cotton tensor duality for AdS4 black holes

abstract:
  We consider the theory of gravitational quasi-normal modes for general linear
perturbations of AdS4 black holes. Special emphasis is placed on the effective
Schrodinger problems for axial and polar perturbations that realize
supersymmetric partner potential barriers on the half-line. Using the
holographic renormalization method, we compute the energy-momentum tensor for
perturbations satisfying arbitrary boundary conditions at spatial infinity and
discuss some aspects of the problem in the hydrodynamic representation. It is
also observed in this general framework that the energy-momentum tensor of
black hole perturbations and the energy momentum tensor of the gravitational
Chern-Simons action (known as Cotton tensor) exhibit an axial-polar duality
with respect to appropriately chosen supersymmetric partner boundary conditions
on the effective Schrodinger wave-functions. This correspondence applies to
perturbations of very large AdS4 black holes with shear viscosity to entropy
density ratio equal to 1/4\pi, thus providing a dual graviton description of
their hydrodynamic modes. We also entertain the idea that the purely
dissipative modes of black hole hydrodynamics may admit Ricci flow description
in the non-linear regime.


title: Hadron Form Factors in AdS/QCD

abstract:
  We discuss how to calculate form factors using a holographic model of QCD,
mainly focusing on vector, axial, and pseudoscalar mesons. We illustrate the
techniques on gravitational form factors (which are useful for constraining the
generalized parton distributions) as well as quoting the results for
electromagnetic form factors. One striking outcome, comparing the several types
of calculated form factors, is that mesons appear noticeably more compact when
measured by the gravitational form factors than when measured by the charge
form factor.


title:
Phenomenology and cosmology of millicharged particles and experimental
  prospects for their search

abstract:
  Mirror world, a parallel hidden sector with microphysics identical to
ordinary particle physics, can have several interesting phenomenological and
astrophysical implications and mirror matter can be a natural candidate for
dark matter in the universe. In this thesis we analyze in detail some of its
implications in cosmology, in particular at the primordial nucleosynthesis
epoch. Big Bang Nucleosynthesis limits require that the temperature T' of the
mirror world should be at least twice lower than that of the ordinary world T.
We present numerical calculations regarding the nucleosynthesis epoch and
calculate the light and heavier element abundances in both ordinary and mirror
worlds as a function of x=T'/T. While the mirror world should be essentially
Helium dominated, we show that the heavier elements primordial abundances in
mirror world can be significantly higher than in the ordinary world. We also
study the cosmological bounds on the kinetic mixing between the photon and
mirror photon which in fact renders the mirror particles "millicharged" with
respect to the ordinary photon, with small electric charges proportional to the
photon kinetic mixing parameter. These bounds are important regarding the
possibility of mirror dark matter detection in the DAMA/Libra experiment. This
Diploma Thesis was defended in the University of L'Aquila in October 2007.


title: Gravitational intraction on quantum level and consequences thereof

abstract:
  The notion of gravitational emission as an emission of the same level with
electromagnetic emission is based on the proven fact of existence of electrons
stationary states in its own gravitational field, characterized by
gravitational constant


title: Concentration of measure and mixing for Markov chains

abstract:
  We consider Markovian models on graphs with local dynamics. We show that,
under suitable conditions, such Markov chains exhibit both rapid convergence to
equilibrium and strong concentration of measure in the stationary distribution.
We illustrate our results with applications to some known chains from computer
science and statistical mechanics.


title: The Discovery of Stellar Oscillations in the K Giant $\iota$ Dra

abstract:
  $\iota$ Dra (HIP 75458) is a well-known example for a K giant hosting a
substellar companion since its discovery by Frink et al. (2002). We present
radial velocity measurements of this star from observations taken with three
different instruments spanning nearly 8 years. They show more clearly that the
RV period is long-lived and coherent thus supporting the companion hypothesis.
The longer time baseline now allows for a more accurate determination of the
orbit with a revised period of P=511 d and an additional small linear trend,
indicative of another companion in a wide orbit. Moreover we show that the star
exhibits low amplitude, solar like oscillations with frequencies around 3-4
d$^{-1}$ (34.7-46.3 $\mu$Hz).


title:
On the structure of the set of bifurcation points of periodic solutions
  for multiparameter Hamiltonian systems

abstract:
  This paper deals with periodic solutions of the Hamilton equation with many
parameters. Theorems on global bifurcation of solutions with periods $2\pi/j,$
$j\in\mathbb{N},$ from a stationary point are proved. The Hessian matrix of the
Hamiltonian at the stationary point can be singular. However, it is assumed
that the local topological degree of the gradient of the Hamiltonian at the
stationary point is nonzero. It is shown that (global) bifurcation points of
solutions with given periods can be identified with zeros of appropriate
continuous functions on the space of parameters. Explicit formulae for such
functions are given in the case when the Hessian matrix of the Hamiltonian at
the stationary point is block-diagonal. Symmetry breaking results concerning
bifurcation of solutions with different minimal periods are obtained. A
geometric description of the set of bifurcation points is given. Examples of
constructive application of the theorems proved to analytical and numerical
investigation and visualization of the set of all bifurcation points in given
domain are provided.
  This paper is based on a part of the author's thesis [W. Radzki, ``Branching
points of periodic solutions of autonomous Hamiltonian systems'' (Polish), PhD
thesis, Nicolaus Copernicus University, Faculty of Mathematics and Computer
Science, Toru\'{n}, 2005].


title:
Control of state and state entanglement with a single auxiliary
  subsystem

abstract:
  We present a strategy to control the evolution of a quantum system. The novel
aspect of this protocol is the use of a \emph{single auxiliary subsystem}. Two
applications are given, one which allows for state preservation and another
which controls the degree of entanglement of a given initial state.


title: Vub extraction using the Analytic Coupling model

abstract:
  We summarize the main characteristics and recent results on B->Xulnu decays
of a model based on soft-gluon resummation and an analytic time-like QCD
coupling.


title: The Kodaira Dimension of Lefschetz Fibrations

abstract:
  In this note, we verify that the complex Kodaira dimension $\kappa^h$ equals
the symplectic Kodaira dimension $\kappa^s$ for smooth 4-manifolds with complex
and symplectic structures. We also calculate the Kodaira dimension for many
Lefschetz fibrations.


title: The cohomological equation for partially hyperbolic diffeomorphisms

abstract:
  We establish a theory for the existence and regularity of solutions to the
cohomological equation over an accessible, partially hyperbolic diffeomorphism.
As a by-product of our techniques, we show that for $r>1$, any $C^r$
homogeneous, locally compact submanifold of a $C^r$ manifold is in fact a $C^r$
submanifold.


title:
Observations of an Impurity-driven Hysteresis Behavior in Ice Crystal
  Growth at Low Pressure

abstract:
  We describe observations of a novel hysteresis behavior in the growth of ice
crystals under near-vacuum conditions. Above a threshold supersaturation, we
find that the ice growth rate often exhibits a sudden increase that we
attribute to an impurity-driven growth instability. We examine possible
mechanisms for this instability, which can be used to produce clean, faceted
ice surfaces.


title: On the geometrized Skyrme and Faddeev models

abstract:
  The higher-power derivative terms involved in both Faddeev and Skyrme energy
functionals correspond to $\sigma_2$-energy, introduced by Eells and Sampson.
The paper provides a detailed study of the first and second variation formulae
associated to this energy. Some classes of (stable) critical maps are outlined.


title:
Feshbach resonances and mesoscopic phase separation near a quantum
  critical point in multiband FeAs-based superconductors

abstract:
  High Tc superconductivity in FeAs-based multilayers (pnictides), evading
temperature decoherence effects in a quantum condensate, is assigned to a
Feshbach resonance (called also shape resonance) in the exchange-like interband
pairing. The resonance is switched on by tuning the chemical potential at an
electronic topological transition (ETT) near a band edge, where the Fermi
surface topology of one of the subbands changes from 1D to 2D topology. We show
that the tuning is realized by changing i) the misfit strain between the
superconducting planes and the spacers ii) the charge density and iii) the
disorder. The system is at the verge of a catastrophe i.e. near a structural
and magnetic phase transition associated with the stripes (analogous to the 1/8
stripe phase in cuprates) order to disorder phase transition. Fine tuning of
both the chemical potential and the disorder pushes the critical temperature Ts
of this phase transition to zero giving a quantum critical point. Here the
quantum lattice and magnetic fluctuations promote the Feshbach resonance of the
exchange-like anisotropic pairing. This superconducting phase that resists to
the attacks of temperature is shown to be controlled by the interplay of the
hopping energy between stripes and the quantum fluctuations. The
superconducting gaps in the multiple Fermi surface spots reported by the recent
ARPES experiment of D. V. Evtushinsky et al. arXiv:0809.4455 are shown to
support the Feshbach scenario.


title: An Information Geometric Framework for Dimensionality Reduction

abstract:
  This report concerns the problem of dimensionality reduction through
information geometric methods on statistical manifolds. While there has been
considerable work recently presented regarding dimensionality reduction for the
purposes of learning tasks such as classification, clustering, and
visualization, these methods have focused primarily on Riemannian manifolds in
Euclidean space. While sufficient for many applications, there are many
high-dimensional signals which have no straightforward and meaningful Euclidean
representation. In these cases, signals may be more appropriately represented
as a realization of some distribution lying on a statistical manifold, or a
manifold of probability density functions (PDFs). We present a framework for
dimensionality reduction that uses information geometry for both statistical
manifold reconstruction as well as dimensionality reduction in the data domain.


title:
The exact evaluation of the corner-to-corner resistance of an M x N
  resistor network: Asymptotic expansion

abstract:
  We study the corner-to-corner resistance of an M x N resistor network with
resistors r and s in the two spatial directions, and obtain an asymptotic
expansion of its exact expression for large M and N. For M = N, r = s =1, our
result is
  R_{NxN} = (4/pi) log N + 0.077318 + 0.266070/N^2 - 0.534779/N^4 + O(1/N^6).


title:
Coherent terahertz needle radiation emission mechanism from
  nanostructured ferromagnetic metal films excited by femtosecond laser pulses

abstract:
  A coherent terahertz needle radiation emission mechanism is proposed. This
mechanism can be realized in the experiments on femtosecond laser pulses
interacting with surface of nanostructured ferromagnetic metal film. The
proposed mechanism is based on exciting of coupled coherent phonon-magnon modes
on a nanostructured metal surface by laser femtosecond pulse. The value of the
Poynting vector for the terahertz radiation is estimated.


title: A Convection Chamber for Measuring Ice Crystal Growth Dynamics

abstract:
  We present the design of a general-purpose convection chamber that produces a
stable environment for studying the growth of ice crystals from water vapor in
the presence of a background gas. Crystals grow in free fall inside the
chamber, where the temperature and supersaturation are well characterized and
surprisingly uniform. As crystals fall and land on a substrate, their
dimensions are measured using direct imaging and broad-band interferometry. We
also present a parameterized model of the supersaturation inside the chamber
that is based on differential hygrometer measurements. Using this chamber, we
are able to observe the growth and morphology of ice crystals over a broad
range of conditions, as a function of temperature, supersaturation, gas
constituents, gas pressure, growth time, and other parameters.


title: Holographic model of superfluidity

abstract:
  We study a holographic model of a relativistic quantum system with a global
U(1) symmetry, at non-zero temperature and density. When the temperature falls
below a critical value, we find a second-order superfluid phase transition with
mean-field critical exponents. In the symmetry-broken phase, we determine the
speed of second sound as a function of temperature. As the velocity of the
superfluid component relative to the normal component increases, the superfluid
transition goes through a tricritical point and becomes first-order.


title: ADONIS high contrast infrared imaging of Sirius-B

abstract:
  Sirius is the brightest star in the sky and a strong source of diffuse light
for modern telescopes so that the immediate surroundings of the star are still
poorly known. We study the close surroundings of the star (2 to 25 arcsec) by
means of adaptive optics and coronographic device in the near-infrared, using
the ESO/ADONIS system. The resulting high contrast images in the JHKs bands
have a resolution of ~ 0.2 arcsec and limiting apparent magnitude ranging from
mK = 9.5 at 3 arcsec, from Sirius-A to mK = 13.1 at 10 arcsec. These are the
first and deepest images of the Sirius system in this infrared range. From
these observations, accurate infrared photometry of the Sirius-B white dwarf
companion is obtained. The JH magnitudes of Sirius-B are found to agree with
expectations for a DA white dwarf of temperature (T=25000K) and gravity (log(g)
= 8.5), consistent with the characteristics determined from optical
observations. However, a small, significant excess is measurable for the K
band, similar to that detected for "dusty" isolated white dwarfs harbouring
suspected planetary debris. The possible existence of such circumstellar
material around Sirius-B has still to be confirmed by further observations.
These deep images allow us to search for small but yet undetected companions to
Sirius. Apart from Sirius-B, no other source is detected within the total 25
arcsec field. The minimum detectable mass is around 10 MJup inside the
planetary limit, indicating that an extrasolar planet at a projected distance
of ~ 25 AU from Sirius would have been detected (abridged abstract).


title: Unparticle Searches Through Low Energy Parity Violating Asymmetry

abstract:
  In this paper, we study the effects of the unparticles on the
parity-violating asymmetry for the low energy electron-electron scattering,
  $e^-e^-\to e^-e^-$. Using the data from the E158 experiment at SLAC we
extract the limits on the unparticle coupling $\lambda_{AV}$, and on the the
energy scale $\Lambda$ at 95% C.L. for various values of the scaling dimension
$d$.


title: Algebraic solutions of the sixth Painleve equation

abstract:
  We describe all finite orbits of an action of the extended modular group
$\bar{\Lambda}$ on conjugacy classes of SL(2,C)-triples. The result is used to
classify all algebraic solutions of the general Painleve VI equation up to
parameter equivalence.


title: Noncommutative ball maps

abstract:
  In this paper, we analyze problems involving matrix variables for which we
use a noncommutative algebra setting. To be more specific, we use a class of
functions (called NC analytic functions) defined by power series in
noncommuting variables and evaluate these functions on sets of matrices of all
dimensions; we call such situations dimension-free. These types of functions
have recently been used in the study of dimension-free linear system
engineering problems.
  In this paper we characterize NC analytic maps that send dimension-free
matrix balls to dimension-free matrix balls and carry the boundary to the
boundary; such maps we call "NC ball maps". We find that up to normalization,
an NC ball map is the direct sum of the identity map with an NC analytic map of
the ball into the ball. That is, "NC ball maps" are very simple, in contrast to
the classical result of D'Angelo on such analytic maps over C. Another
mathematically natural class of maps carries a variant of the noncommutative
distinguished boundary to the boundary, but on these our results are limited.
  We shall be interested in several types of noncommutative balls, conventional
ones, but also balls defined by constraints called Linear Matrix Inequalities
(LMI). What we do here is a small piece of the bigger puzzle of understanding
how LMIs behave with respect to noncommutative change of variables.


title: Isotropic AdS/CFT fireball

abstract:
  We study the AdS/CFT thermodynamics of the spatially isotropic counterpart of
the Bjorken similarity flow in d-dimensional Minkowski space with d>=3, and of
its generalisation to linearly expanding d-dimensional
Friedmann-Robertson-Walker cosmologies with arbitrary values of the spatial
curvature parameter k. The bulk solution is a nonstatic foliation of the
generalised Schwarzschild-AdS black hole with a horizon of constant curvature
k. The boundary matter is an expanding perfect fluid that satisfies the first
law of thermodynamics for all values of the temperature and the spatial
curvature, but it admits a description as a scale-invariant fluid in local
thermal equilibrium only when the inverse Hawking temperature is negligible
compared with the spatial curvature length scale. A Casimir-type term in the
holographic energy-momentum tensor is identified from the threshold of black
hole formation and is shown to take different forms for k>=0 and k<0.


title:
Residue network in protein native structure belongs to the universality
  class of three dimensional critical percolation cluster

abstract:
  A single protein molecule is regarded as a contact network of amino-acid
residues. Some studies have indicated that this network is a small world
network (SWN), while other results have implied that this is a fractal network
(FN). However, SWN and FN are essentially different in the dependence of the
shortest path length on the number of nodes. In this paper, we investigate this
dependence in the residue contact networks of proteins in native structures,
and show that the networks are not SWN but FN. FN is generally characterized by
several dimensions. Among them, we focus on three dimensions; the network
topological dimension $D_c$, the fractal dimension $D_f$, and the spectral
dimension $D_s$. We find that proteins universally yield $D_c \approx 1.9$,
$D_f \approx 2.5$ and $Ds \approx 1.3$. These values are in surprisingly good
coincidence with those in three dimensional critical percolation cluster. Hence
the residue contact networks in the protein native structures belong to the
universality class of three dimensional percolation cluster. The criticality is
relevant to the ambivalent nature of the protein native structures, i.e., the
coexistence of stability and instability, both of which are necessary for a
protein to function as a molecular machine or an allosteric enzyme.


title: Ahlfors-David regular sets and bilipschitz maps

abstract:
  Given two Ahlfors-David regular sets in metric spaces, we study the question
whether one of them has a subset bilipschitz equivalent with the other.


title: Square-Free Rings And Their Automorphism Group

abstract:
  Finite-dimensional square-free algebras have been completely characterized by
Anderson and D'Ambrosia as certain twisted semigroup algebras over a
square-free semigroup S with coefficients in a field K. D'Ambrosia extended the
definition of square-free to artinian rings with unity and showed every
square-free ring has an associated division ring D and square-free semigroup S.
We show a square-free ring can be characterized as a twisted semigroup ring
over a square-free semigroup S with coefficients in a division ring D. Also, to
each square-free ring there exists a short exact sequence connecting the outer
automorphisms of a square-free ring to certain cohomology groups related to S
and D.


title:
Stable and "bounded excursion" gravastars, and black holes in Einstein's
  theory of gravity

abstract:
  Dynamical models of prototype gravastars are constructed and studied. The
models are the Visser-Wiltshire three-layer gravastars, in which an infinitely
thin spherical shell of a perfect fluid with the equation of state $p =
(1-\gamma)\sigma$ divides the whole spacetime into two regions, where the
internal region is de Sitter, and the external is Schwarzschild. When $\gamma <
1$ and $\Lambda \not= 0$, it is found that in some cases the models represent
stable gravastars, and in some cases they represent "bounded excursion" stable
gravastars, where the thin shell is oscillating between two finite radii, while
in some other cases they collapse until the formation of black holes. However,
when $\gamma \ge 1$, even with $\Lambda \not= 0$, only black holes are found.
In the phase space, the region for both stable gravastars and "bounded
excursion" gravastars is very small in comparison to that of black holes,
although it is not completely empty.


title: Theoretical investigation of magnetic order in ReOFeAs, Re = Ce, Pr

abstract:
  Density functional theory (DFT) calculations are carried out on ReOFeAs, Re =
Ce, Pr, the parent compounds of the high-T$_c$ superconductors
ReO$_{1-x}$F$_{x}$FeAs, in order to determine the magnetic order of the ground
state. It is found that the magnetic moments on the Fe sites adopt a collinear
antiferromagnetic order, similar to the case of LaOFeAs. Within the generalized
gradient approximation along with Coulomb onsite repulsion (GGA+U), we show
that the Re magnetic moments also adopt an antiferromagnetic order for which,
within the ReO layer, same spin Re sites lie along a zigzag line perpendicular
to the Fe spin stripes. While within GGA the Re 4f band crosses the Fermi
level, upon inclusion of onsite Coulomb interaction the 4f band splits and
moves away from the Fermi level, making ReOFeAs a Mott insulator.


title: Random Heegaard splittings

abstract:
  A random Heegaard splitting is a 3-manifold obtained by using a random walk
of length n on the mapping class group as the gluing map between two
handlebodies. We show that the joint distribution of random walks of length n
and their inverses is asymptotically independent, and converges to the product
of the harmonic and reflected harmonic measures defined by the random walk. We
use this to show that the translation length on the curve complex of a random
walk grows linearly in the length of the walk, and similarly, that distance in
the curve complex between the disc sets of a random Heegaard splitting grows
linearly in n. In particular, this implies that a random Heegaard splitting is
hyperbolic with asymptotic probability one.


title: Multi-Armed Bandits in Metric Spaces

abstract:
  In a multi-armed bandit problem, an online algorithm chooses from a set of
strategies in a sequence of trials so as to maximize the total payoff of the
chosen strategies. While the performance of bandit algorithms with a small
finite strategy set is quite well understood, bandit problems with large
strategy sets are still a topic of very active investigation, motivated by
practical applications such as online auctions and web advertisement. The goal
of such research is to identify broad and natural classes of strategy sets and
payoff functions which enable the design of efficient solutions. In this work
we study a very general setting for the multi-armed bandit problem in which the
strategies form a metric space, and the payoff function satisfies a Lipschitz
condition with respect to the metric. We refer to this problem as the
"Lipschitz MAB problem". We present a complete solution for the multi-armed
problem in this setting. That is, for every metric space (L,X) we define an
isometry invariant which bounds from below the performance of Lipschitz MAB
algorithms for X, and we present an algorithm which comes arbitrarily close to
meeting this bound. Furthermore, our technique gives even better results for
benign payoff functions.


title:
Thresholded Basis Pursuit: An LP Algorithm for Achieving Optimal Support
  Recovery for Sparse and Approximately Sparse Signals from Noisy Random
  Measurements

abstract:
  In this paper we present a linear programming solution for sign pattern
recovery of a sparse signal from noisy random projections of the signal. We
consider two types of noise models, input noise, where noise enters before the
random projection; and output noise, where noise enters after the random
projection. Sign pattern recovery involves the estimation of sign pattern of a
sparse signal. Our idea is to pretend that no noise exists and solve the
noiseless $\ell_1$ problem, namely, $\min \|\beta\|_1 ~ s.t. ~ y=G \beta$ and
quantizing the resulting solution. We show that the quantized solution
perfectly reconstructs the sign pattern of a sufficiently sparse signal.
Specifically, we show that the sign pattern of an arbitrary k-sparse,
n-dimensional signal $x$ can be recovered with $SNR=\Omega(\log n)$ and
measurements scaling as $m= \Omega(k \log{n/k})$ for all sparsity levels $k$
satisfying $0< k \leq \alpha n$, where $\alpha$ is a sufficiently small
positive constant. Surprisingly, this bound matches the optimal
\emph{Max-Likelihood} performance bounds in terms of $SNR$, required number of
measurements, and admissible sparsity level in an order-wise sense. In contrast
to our results, previous results based on LASSO and Max-Correlation techniques
either assume significantly larger $SNR$, sublinear sparsity levels or
restrictive assumptions on signal sets. Our proof technique is based on noisy
perturbation of the noiseless $\ell_1$ problem, in that, we estimate the
maximum admissible noise level before sign pattern recovery fails.


title: Optimum unambiguous identification of d unknown pure qudit states

abstract:
  We address the problem of unambiguously identifying the state of a probe
qudit with the state of one of d reference qudits. The reference states are
assumed pure and linearly independent but we have no knowledge of them. The
state of the probe qudit is assumed to coincide equally likely with either one
of the d unknown reference states. We derive the optimum measurement strategy
that maximizes the success probability of unambiguous identification and find
that the optimum strategy is a generalized measurement. We give both the
measurement operators and the optimum success probability explicitly.
Technically, the problem we solve amounts to the optimum unambiguous
discrimination of d known mixed quantum states.


title: Hyperbolic Supersymmetric Quantum Hall Effect

abstract:
  Developing a non-compact version of the SUSY Hopf map, we formulate the
quantum Hall effect on a super-hyperboloid. Based on $OSp(1|2)$ group
theoretical methods, we first analyze the one-particle Landau problem, and
successively explore the many-body problem where Laughlin wavefunction,
hard-core pseudo-potential Hamiltonian and topological excitations are derived.
It is also shown that the fuzzy super-hyperboloid emerges in the lowest Landau
level.


title:
Gamma-ray halo around 3C 279: looking through the Sun on the 8th of
  October

abstract:
  We discuss how the solar occultations of bright sources of energetic gamma
rays can be used to extract non-trivial physical and astrophysical information,
including the angular size of the image when it is significantly smaller than
the experiment's angular resolution. We analyze the EGRET data and discuss
prospects for other instruments. The Fermi Gamma Ray Space Telescope will be
able to constrain the size of a possible halo around 3C~279 from observations
it makes on the 8th of October each year.


title: Absolutely simple Prymians of trigonal curves

abstract:
  Using Galois Theory, we construct explicitly absolutely simple (principally
polarized) Prym varieties that are not isomorphic to jacobians of curves even
if we ignore the polarizations. Our approach is based on the previous papers
math/0610138 [math.AG] and math/0605028 [math.AG] .


title: Nearly conformal electroweak sector with chiral fermions

abstract:
  SU(3) gauge theory with dynamical overlap fermions in the 2-index symmetric
(sextet) representation is considered. This model may be a viable model of the
electroweak symmetry breaking sector along the lines of the walking technicolor
paradigm. The number of fermion species is chosen such that the theory is
expected to be below the conformal window. We will discuss how the
epsilon-regime and random matrix theory can be used to test whether at any
given set of parameters (N_c, N_f, representation) the theory is in the
conformal phase or indeed just below it. Quenched Monte Carlo results are
included in the fundamental representation and also preliminary dynamical ones
in the 2-index symmetric representation.


title: On the cohomology of hyperkahler quotients

abstract:
  This paper gives a partial desingularisation construction for hyperk\"ahler
quotients and a criterion for the surjectivity of an analogue of the Kirwan map
to the cohomology of hyperk\"ahler quotients. This criterion is applied to some
linear actions on hyperk\"ahler vector spaces.


title: Probing technicolor theories with staggered fermions

abstract:
  One exciting possibility of new physics beyond the Standard Model is that the
fundamental Higgs sector is replaced by a strongly-interacting gauge theory,
known as technicolor. A viable theory must break chiral symmetry dynamically,
like in QCD, to generate Goldstone bosons which become the longitudinal
components of the W and Z. By measuring the eigenvalues of the Dirac operator,
one can determine if chiral symmetry is in fact spontaneously broken. We
simulate SU(3) gauge theory with n_s=2 and 3 staggered flavors in the
fundamental representation, corresponding to N_f=8 and 12 flavors in the
continuum limit. Although our first findings show that both theories are
consistent with dynamically broken chiral symmetry and QCD-like behavior,
flavor breaking effects in the spectrum may require further clarifications
before final conclusions can be drawn. We also compare various improved
staggered actions, to suppress this potentially large flavor breaking.


title: On the nonexistence of Einstein metric on 4-manifolds

abstract:
  By using the gluing formulae of the Seiberg-Witten invariant, we show the
nonexistence of Einstein metric on manifolds obtained from a 4-manifold with
nontrivial Seiberg-Witten invariant by performing sufficiently many connected
sums or appropriate surgeries along circles or homologically trivial 2-spheres
with closed oriented 4-manifolds with negative definite intersection form.


title:
Parity violation in $d \vec{\gamma} -> np$ with pionless effective
  theory

abstract:
  We consider a pionless effective theory with dibaryon fields for the
description of the weak process involving two nucleons. We construct leading
order Lagrangians that contain nucleon-dibaryon weak coupling constants. We
calculate the physical observable in the photodisintegration of the deuteron at
threshold and obtain the result in terms of the nucleon-dibaryon weak coupling
constants. Relation to existing calculations is discussed.


title: Spaces of algebraic and continuous maps between real algebraic varieties

abstract:
  We consider the inclusion of the space of algebraic (regular) maps between
real algebraic varieties in the space of all continuous maps. For a certain
class of real algebraic varieties, which include real projective spaces, it is
well known that the space of real algebraic maps is a dense subset of the space
of all continuous maps. Our first result shows that, for this class of
varieties, the inclusion is also a homotopy equivalence. After proving this, we
restrict the class of varieties to real projective spaces. In this case, the
space of algebraic maps has a ` minimum degree\rq filtration by finite
dimensional subspaces and it is natural to expect that the homotopy types of
the terms of the filtration approximate closer and closer the homotopy type of
the space of continuous mappings as the degree increases. We prove this and
compute the lower bounds of this approximation for ` even\rq components of
these spaces (more precisely, we prove a very similar and closely related
result, and state this one as a conjecture).


title: Merger of Black Holes in the Galactic Center

abstract:
  We present the results of three body simulations focused on understanding the
fates of intermediate mass black holes (IBH) that drift within the central 0.5
pc of the Galaxy. In particular, we modeled the interactions between pairs of
$4000 {\rm M}_{\odot}$ black holes as they orbit a central blac k hole of mass
$4 \times 10^6 {\rm M}_{\odot}$. The simulations performed assume a
Schwarzschild geometry and account for Chandrasekhar dynamical friction as well
as acceleration resulting from energy lost due to gravitational radiation.
  We found the branching ratio for one of the orbiting IBHs to merge with the
CBH was 0.95 and is independent of the inner IBH's initial eccentricity as well
as the rate of sinking. This, coupled with an infall rate of $\sim 10^7 $ yrs
for an IBH to drift into the Galactic center, results in an IBH-CBH merger
every $\lesssim 11$ Myrs. Lastly we found that the IBH-IBH-CBH triple body
system ``resets'' itself, in the sense that a system with an inner I BH with an
initially circular orbit generally left behind an IBH with a large
eccentricity, whereas a system in which the inner IBH had a high eccentricity
($e_0 \sim 0.9$) usually left a remnant with low eccentricity. Branching ratios
for different outcomes are also similar in the two cases.


title: Double-Spinor Superstrings on Coset Superspaces

abstract:
  The double-spinor formalism, proposed by Aisaka and Kazama, provides a basis
for the pure-spinor formalism, which allows manifestly super-Poincare covariant
quantization of superstrings. We extend it to the case of backgrounds realized
by coset superspaces. A general method constructing reparametrization invariant
action is given using two concrete examples, the flat space-time and
AdS(5)xS(5). We find that it is natural to double not only the spinor
coordinates but the whole superspace for describing double-spinor superstrings
on such backgrounds. The reparametrization invariant action has local
symmetries compensating those extra degrees of freedom, which guarantee the
equivalence to the Green-Schwarz formalism.


title: b-Tagging Algorithms and their Performance at ATLAS

abstract:
  The ability to identify jets containing B hadrons is important for the
high-pT physics program of a general-purpose experiment such as ATLAS.
b-tagging is in particular useful for selecting very pure top quark samples,
for studying standard model or supersymmetric Higgs bosons which couple
preferably to heavy objects, for vetoing backgrounds for several physics
channels and finally for searching for new physics beyond the standard model
like supersymmetric particles or heavy gauge bosons. After a review of the
algorithms used to identify b-jets, their anticipated performance is discussed
as well as the impact of selected critical ingredients such as residual
misalignments in the tracker. The prospects to measure the b-tagging
performance in the first few hundreds pb-1 of data with di-jet events as well
as ttbar events are presented. Finally three different physics use cases of
b-tagging are summarised.


title: Cluster tilting for higher Auslander algebras

abstract:
  The concept of cluster tilting gives a higher analogue of classical Auslander
correspondence between representation-finite algebras and Auslander algebras.
The $n$-Auslander-Reiten translation functor $\tau_n$ plays an important role
in the study of $n$-cluster tilting subcategories. We study the category
$\MM_n$ of preinjective-like modules obtained by applying $\tau_n$ to injective
modules repeatedly. We call a finite dimensional algebra $\Lambda$
\emph{$n$-complete} if $\MM_n=\add M$ for an $n$-cluster tilting object $M$.
Our main result asserts that the endomorphism algebra $\End_\Lambda(M)$ is
$(n+1)$-complete. This gives an inductive construction of $n$-complete
algebras. For example, any representation-finite hereditary algebra
$\Lambda^{(1)}$ is 1-complete. Hence the Auslander algebra $\Lambda^{(2)}$ of
$\Lambda^{(1)}$ is 2-complete. Moreover, for any $n\ge1$, we have an
$n$-complete algebra $\Lambda^{(n)}$ which has an $n$-cluster tilting object
$M^{(n)}$ such that $\Lambda^{(n+1)}=\End_{\Lambda^{(n)}}(M^{(n)})$. We give
the presentation of $\Lambda^{(n)}$ by a quiver with relations. We apply our
results to construct $n$-cluster tilting subcategories of derived categories of
$n$-complete algebras.


title: Fidelity susceptibility for SU(2)-invariant states

abstract:
  We study the fidelity susceptibility of two SU(2)-invariant reduced density
matrices. Due to the commuting property of these matrices, analytical results
for reduced fidelity susceptibility are obtained and can be applied to study
quantum phase transitions in SU(2)-invariant systems. As an example, we analyze
the quantum criticality of the spin-one bilinear-biquadratic model via the
fidelity approach.


title: Light-Front Holography: A First Approximation to QCD

abstract:
  Starting from the Hamiltonian equation of motion in QCD, we identify an
invariant light-front coordinate $\zeta$ which allows the separation of the
dynamics of quark and gluon binding from the kinematics of constituent spin and
internal orbital angular momentum. The result is a single variable light-front
Schrodinger equation for QCD which determines the eigenspectrum and the
light-front wavefunctions of hadrons for general spin and orbital angular
momentum. This light-front wave equation is equivalent to the equations of
motion which describe the propagation of spin-$J$ modes on anti-de Sitter (AdS)
space.


title: Cosmological interplay between general relativity and particle physics

abstract:
  We clearly formulate and study further a conjecture of effective field theory
interaction with gravity in the cosmological context. The conjecture stems from
the fact that the melding of quantum theory and gravity typically indicates the
presence of an inherent UV cutoff. Taking note of the physical origin of this
UV cutoff, that the background metric fluctuations does not allow QFT to
operate with a better precision than the background space resolution, we
conjecture that the converse statement might also be true. That is, an
effective field theory could not perceive the background space with a better
precision than it is allowed by its intrinsic UV scale. Some of the subtleties
and cosmological implications of this conjecture are explored.


title: Production of W and Z bosons accompanied by jets at LHC startup

abstract:
  We report on potential for measurement of W and Z boson production
accompanied by jets at the CMS experiment. Of particular interest are jet
multiplicity and Pt distributions. The 10/pb to 100/pb datasets expected in the
startup year of operation of LHC are likely to already provide information
beyond the reach of the Tevatron collider both in jet multiplicity and Pt
range. We are especially interested in understanding the ratios of W+jets to
Z+jets distributions by comparing them to next-to-leading order Monte Carlo
generators, as these processes present a formidable background for searches of
new physics phenomena.


title:
Search for neutron - mirror neutron oscillations in a laboratory
  experiment with ultracold neutrons

abstract:
  Mirror matter is considered as a candidate for dark matter. In connection
with this an experimental search for neutron - mirror neutron (nn') transitions
has been carried out using storage of ultracold neutrons in a trap with
different magnetic fields. As a result, a new limit for the neutron - mirror
neutron oscillation time has been obtained, tau_osc >= 448 s (90% C.L.),
assuming that there is no mirror magnetic field larger than 100 nT. Besides a
first attempt to obtain some restriction for mirror magnetic field has been
done.


title:
Search for Maximal Flavor Violating Scalars in Same-Charge Lepton Pairs
  in $p\bar{p}$ Collisions at $\sqrt{s} = 1.96$ TeV

abstract:
  Models of Maximal Flavor Violation (MxFV) in elementary particle physics may
contain at least one new scalar SU$(2)$ doublet field $\Phi_{FV} =
(\eta^0,\eta^+)$ that couples the first and third generation quarks ($q_1,q_3$)
via a Lagrangian term $\mathcal{L}_{FV} = \xi_{13} \Phi_{FV} q_1 q_3$. These
models have a distinctive signature of same-charge top-quark pairs and evade
flavor-changing limits from meson mixing measurements. Data corresponding to 2
fb$^{-1}$ collected by the CDF II detector in $p\bar{p}$ collisions at
$\sqrt{s} = 1.96$ TeV are analyzed for evidence of the MxFV signature. For a
neutral scalar $\eta^0$ with $m_{\eta^0} = 200$ GeV/$c^2$ and coupling
$\xi_{13}=1$, $\sim$ 11 signal events are expected over a background of $2.1
\pm 1.8$ events. Three events are observed in the data, consistent with
background expectations, and limits are set on the coupling $\xi_{13}$ for
$m_{\eta^0} = 180-300$ GeV/$c^2$.


title: DEFROST: A New Code for Simulating Preheating after Inflation

abstract:
  At the end of inflation, dynamical instability can rapidly deposit the energy
of homogeneous cold inflaton into excitations of other fields. This process,
known as preheating, is rather violent, inhomogeneous and non-linear, and has
to be studied numerically. This paper presents a new code for simulating scalar
field dynamics in expanding universe written for that purpose. Compared to
available alternatives, it significantly improves both the speed and the
accuracy of calculations, and is fully instrumented for 3D visualization. We
reproduce previously published results on preheating in simple chaotic
inflation models, and further investigate non-linear dynamics of the inflaton
decay. Surprisingly, we find that the fields do not want to thermalize quite
the way one would think. Instead of directly reaching equilibrium, the
evolution appears to be stuck in a rather simple but quite inhomogeneous state.
In particular, one-point distribution function of total energy density appears
to be universal among various two-field preheating models, and is exceedingly
well described by a lognormal distribution. It is tempting to attribute this
state to scalar field turbulence.


title:
Charge state of the O$_{2}$ molecule during silicon oxidation through
  hybrid functional calculations

abstract:
  We study the charge state of the diffusing O$_2$ molecule during silicon
oxidation through hybrid functional calculations. We calculate charge
transition levels of O$_2$ in bulk SiO$_2$ and use theoretical band offsets to
align these levels with respect to the Si band edges. To overcome the band-gap
problem of semilocal density fuctionals, we employ hybrid functionals with both
predefined and empirically adjusted mixing coefficients. We find that the
charge transition level $\epsilon^{0/-}$ in bulk SiO$_2$ occurs at $\sim$1.1 eV
above the silicon conduction band edge, implying that the O$_2$ molecule
diffuses through the oxide in the neutral charge state. While interfacial
effects concur to lower the charge transition level, our estimates suggest that
the neutral charge state persists until silicon oxidation.


title:
Dynamic entanglement in oscillating molecules and potential biological
  implications

abstract:
  We demonstrate that entanglement can persistently recur in an oscillating
two-spin molecule that is coupled to a hot and noisy environment, in which no
static entanglement can survive. The system represents a non-equilibrium
quantum system which, driven through the oscillatory motion, is prevented from
reaching its (separable) thermal equilibrium state. Environmental noise,
together with the driven motion, plays a constructive role by periodically
resetting the system, even though it will destroy entanglement as usual. As a
building block, the present simple mechanism supports the perspective that
entanglement can exist also in systems which are exposed to a hot environment
and to high levels of de-coherence, which we expect e.g. for biological
systems. Our results furthermore suggest that entanglement plays a role in the
heat exchange between molecular machines and environment. Experimental
simulation of our model with trapped ions is within reach of the current
state-of-the-art quantum technologies.


title: The vacuum bubbles in de Sitter background and black hole pair creation

abstract:
  We study the possible types of the nucleation of vacuum bubbles. We classify
vacuum bubbles in de Sitter background and present some numerical solutions.
The thin-wall approximation is employed to obtain the nucleation rate and the
radius of vacuum bubbles. With careful analysis we confirm that Parke's formula
is also applicable to the large true vacuum bubbles. The nucleation of the
false vacuum bubble in de Sitter background is also evaluated. The tunneling
process in the potential with degenerate vacua is analyzed as the limiting
cases of the large true vacuum bubble and false vacuum bubble. Next, we
consider the pair creation of black holes in the background of bubble
solutions. We obtain static bubble wall solutions of junction equation with
black hole pair. The masses of created black holes are uniquely determined by
the cosmological constant and surface tension on the wall. Finally, we obtain
the rate of pair creation of black holes.


title:
The signature of the Ricci curvature of left invariant Riemannian
  metrics on 4-dimensional Lie groups

abstract:
  In this paper, we present the classification of all possible signatures of
the Ricci curvature of left-invariant Riemannian metrics on 4-dimensional Lie
groups and discuss some related questions.


title: Spectral conditions for positive maps

abstract:
  We provide a partial classification of positive linear maps in matrix
algebras which is based on a family of spectral conditions. This construction
generalizes celebrated Choi example of a map which is positive but not
completely positive. It is shown how the spectral conditions enable one to
construct linear maps on tensor products of matrix algebras which are positive
but only on a convex subset of separable elements. Such maps provide basic
tools to study quantum entanglement in multipartite systems.


title: Properties of doubly charmed baryons in the quark-diquark model

abstract:
  Baryons containing two heavy quarks are important and interesting systems to
study the quark-diquark structure of baryons and to understand the dynamics of
QCD at hadronic scale. The Selex Collaboration has recently reported the
discovery of $\Xi_{cc}$ with a mass of 3.519 Ge$V$. However, other groups such
as Babar, Belle and Focus have all failed to confirm this state. So there is a
demand to review this state both theoretically and experimentally. We report
here the spectra and magnetic moments of $ccq(q\in u,d,s)$ systems using
coulomb plus Martin potential. Here the two heavy quarks are considered for the
diquark states. The same potential form is used for the diquark interaction as
well as for the quark-diquark interaction. The chromomagnetic one gluon
exchange interaction are perturbatively treated here to get the masses of
$J^P={{1/2}}^{+}$ and $J^P={{3/2}}^{+}$ states. Accordingly, we obtain
$\Xi^{++}_{cc}$ (3519, 3555), $\Xi^{+}_{cc}$ (3527, 3562) and $\Omega^{+}_{cc}$
(3648,3688) states of the $ccq$ $({1/2}^{+},{3/2}^{+})$ combinations. Our
predictions are in accordance with the SELEX result for $\Xi^{++}_{cc}$ (3519)
and other model predictions. Predictions of other properties of these $ccq$
systems will be presented in detail.


title: Contact conductance between graphene and quantum wires

abstract:
  The contact conductance between graphene and two quantum wires which serve as
the leads to connect graphene and electron reservoirs is theoretically studied.
Our investigation indicates that the contact conductance depends sensitively on
the graphene-lead coupling configuration. When each quantum wire couples solely
to one carbon atom, the contact conductance vanishes at the Dirac point if the
two carbon atoms coupling to the two leads belong to the same sublattice of
graphene. We find that such a feature arises from the chirality of the Dirac
electron in graphene. Such a chirality associated with conductance zero
disappears when a quantum wire couples to multiple carbon atoms. The general
result irrelevant to the coupling configuration is that the contact conductance
decays rapidly with the increase of the distance between the two leads. In
addition, in the weak graphene-lead coupling limit, when the distance between
the two leads is much larger than the size of the graphene-lead contact areas
and the incident electron energy is close to the Dirac point, the contact
conductance is proportional to the square of the product of the two
graphene-lead contact areas, and inversely proportional to the square of the
distance between the two leads.


title:
A Global Energetic Model for Microquasars: preliminary results and
  spectral energy distributions

abstract:
  We present preliminary results and observables from a model of microquasar
based on a theoretical framework where stationary, powerful, compact jets are
launched and then accelerated from an inner magnetized disk. This model aim at
providing a consistent picture of microquasars in all their spectral states. It
is composed of an outer standard accretion disk down to a variable transition
radius where it changes to a magnetized disk, called the Jet Emitting Disk
(JED). The theoretical framework providing the heating, we solve the radiative
equilibrium and obtain the JED structure. Our JED solutions are rich, and
reproduce the already known scheme where a cold optically-thick and a hot
optically-thin solutions bracket a thermally unstable one. We present the model
and preliminary results, whith a first attempt at reproducing the observed SED
of XTE J1118+480.


title:
Spin-dependent electron transport through a parallel double-quantum-dot
  structure

abstract:
  Electron transport properties in a parallel double-quantum-dot structure with
three-terminals are theoretically studied. By introducing a local Rashba
spin-orbit coupling, we find that an incident electron from one terminal can
select a specific terminal to depart from the quantum dots according to its
spin state. As a result, spin polarization and spin separation can be
simultaneously realized in this structure. And spin polarizations in different
terminals can be inverted by tuning the structure parameters. The underlying
quantum interference that gives rise to such a result is analyzed in the
language of Feynman paths for the electron transmission.


title:
A martingale-transform goodness-of-fit test for the form of the
  conditional variance

abstract:
  In the common nonparametric regression model the problem of testing for a
specific parametric form of the variance function is considered. Recently Dette
and Hetzler (2008) proposed a test statistic, which is based on an empirical
process of pseudo residuals. The process converges weakly to a Gaussian process
with a complicated covariance kernel depending on the data generating process.
In the present paper we consider a standardized version of this process and
propose a martingale transform to obtain asymptotically distribution free tests
for the corresponding Kolmogorov-Smirnov and Cram\'{e}r-von-Mises functionals.
The finite sample properties of the proposed tests are investigated by means of
a simulation study.


title: Data-driven Estimations of Z, W and Top Backgrounds

abstract:
  The Standard Model processes of W, Z and top quark production in association
with jets constitute a major background to searches for Supersymmetry at the
LHC. We describe recent work performed in the ATLAS Collaboration to estimate
these backgrounds for a basic SUSY selection, and we discuss methods to derive
them from the first ATLAS data.


title: 16 Propositions to Reconsider the Organization of a Scientific Workshop

abstract:
  Participating a scientific workshop is nowadays often an adventure because
the number of participants do seldom exceed the number of talks. A half-day
workshop is mostly finished at lunchtime, speakers are sometimes not present
and unexcused, and a strict progression of the workshop offers little air for
discussion. And when talks are re-scheduled on short notice in case that a
speech is dropped out, attaining guests definitely wonder why the presenter is
talking about something that does not match the previously announced talk. In
this respect, we believe that the organization of a workshop in the classical
sense must be reconsidered. It is not enough of compelling the presenters to
pay the registration fee only and to let the participants being impassive or
taken away mentally. With this work, we address several propositions to become
implemented in the future workshop organization. With that, we hope to
contribute to the identification of scientific workshops as a place of
interaction.


title: Enhanced Energy-Aware Feedback Scheduling of Embedded Control Systems

abstract:
  Dynamic voltage scaling (DVS) is one of the most effective techniques for
reducing energy consumption in embedded and real-time systems. However,
traditional DVS algorithms have inherent limitations on their capability in
energy saving since they rarely take into account the actual application
requirements and often exploit fixed timing constraints of real-time tasks.
Taking advantage of application adaptation, an enhanced energy-aware feedback
scheduling (EEAFS) scheme is proposed, which integrates feedback scheduling
with DVS. To achieve further reduction in energy consumption over pure DVS
while not jeopardizing the quality of control, the sampling period of each
control loop is adapted to its actual control performance, thus exploring
flexible timing constraints on control tasks. Extensive simulation results are
given to demonstrate the effectiveness of EEAFS under different scenarios.
Compared with the optimal pure DVS scheme, EEAFS saves much more energy while
yielding comparable control performance.