title: Second RPA and correlated realistic interactions

abstract:
  We examine the response of closed-shell nuclei using a correlated
interaction, derived with the Unitary Correlation Operator Method (UCOM) from
the Argonne V18 potential, in second RPA (SRPA) calculations. The same
correlated two-body interaction is used to derive the Hartree-Fock ground state
and the SRPA equations. Our results show that the coupling of particle-hole
states to higher-order configurations produces sizable effects compared with
first-order RPA. A much improved description of the isovector dipole and
isoscalar quadrupole resonances is obtained, thanks in part to the more
fundamental treatment of the nucleon effective mass offered by SRPA. The
present work suggests the prospect of describing giant resonance properties
realistically and consistently within extended RPA theories. Self-consistency
issues of the present SRPA method and residual three-body effects are pointed
out.


title: Reliability of regulatory networks and its evolution

abstract:
  The problem of reliability of the dynamics in biological regulatory networks
is studied in the framework of a generalized Boolean network model with
continuous timing and noise. Using well-known artificial genetic networks such
as the repressilator, we discuss concepts of reliability of rhythmic
attractors. In a simple evolution process we investigate how overall network
structure affects the reliability of the dynamics. In the course of the
evolution, networks are selected for reliable dynamics. We find that most
networks can be easily evolved towards reliable functioning while preserving
the original function.


title: Radiative decays with a0(980) and f0(980) from ChPT at order p^4

abstract:
  A consistent description of the pi0 pi0 invariant mass distribution in the
phi(1020) -> f0(980) gamma -> pi0 pi0 gamma decay and the pi0 eta in phi(1020)
-> a0(980) gamma -> pi0 eta gamma is suggested. A search for the consequences
of the flavor SU(3) symmetry for the scalar mesons can be based on such an
analysis. In order to accurately treat the pseudoscalar meson dynamics, which
is very important for the scalar meson decays, we employ Resonance Chiral
Theory.


title: On the derived category of a regular toric scheme

abstract:
  Let X be a quasi-compact scheme, equipped with an open covering by affine
schemes. A quasi-coherent sheaf on X gives rise, by taking sections over the
covering sets, to a diagram of modules over the various coordinate rings. The
resulting "twisted" diagram of modules satisfies a certain gluing condition,
stating that the data is compatible with restriction to smaller open sets.
  In case X is a regular toric scheme over an arbitrary commutative ring, we
prove that the unbounded derived category D(X) of quasi-coherent sheaves on X
can be obtained from a category of twisted diagrams which do not necessarily
satisfy any gluing condition by inverting maps which induce homology
isomorphisms on hyper-derived inverse limits. Moreover, we given an explicit
construction of a finite set of weak generators for the derived category.
  For example, if X is projective n-space then D(X) is generated by n+1
successive twists of the structure sheaf; the present paper gives a new
homotopy-theoretic proof of this classical result.
  The approach taken uses the language of model categories, and the machinery
of Bousfield-Hirschhorn colocalisation. The first step is to characterise
colocal objects; these turn out to be homotopy sheaves in the sense that chain
complexes over different open sets agree on intersections up to
quasi-isomorphism only. In a second step it is shown that the homotopy category
of homotopy sheaves is the derived category of X.


title:
Relativistic Invariance of the Phase of a Spherical Wave, relativistic
  Doppler Formula and Poincare's expansion of space

abstract:
  Recently Einstein's invariance of the phase of a plane wave (1905) has been
described as "questionable" (Huang). Another definition of this phase, taking
into account a "relativistically induced optical anisotropy" for isotropic
medium in moving, has been proposed (Gjurkinovski). We suggest (logically) to
determine this "relativistically induced effect" if the isotropic medium is the
vacuum. We prove that the basic Lorentz invariant, in vacuum, is not the phase
of a plane wave but the phase of a spherical wave. According to Poincare an
isotropic spherical wave is not LTed (Lorentz transformed) into an isotropic
spherical wave (Einstein 1905) but LTed into an anisotropic ellipsoidal wave
(relativity of simultaneity). Poincare's ellipsoidal wavefront (1906) is an
{equiphase} surface. The Lorenz gauge is connected with the invariance of the
phase of a spherical wave and the transverse gauge with Einstein's invariant.
We deduce from Poincare's invariant a relativistic Doppler formula which is
unseparable from Poincare's theory of expansion of space and therefore the
measurements of Hubble.


title: Higher-dimensional perturbations of the vacuum energy density

abstract:
  The vacuum energy density arising from the broken supersymmetry of the
(standard-model) fields living on a brane cannot be fully "off-loaded" to the
bulk: even assuming the existence of an effective "self-tuning" mechanism, a
small fraction of the transferred energy "bunces back" to the brane, as a
backreaction of the supersymmetry breaking gravitationally transmitted to the
bulk. In that case the SUSY scale of the brane has to be bounded, to guarantee
the consistency of such a residual energy density with current large-scale
phenomonological constraints. This effect is illustrated by computing the
zero-point energies of the tower of (higher-dimensional) massive states
associated to tensor metric fluctuations on a brane embedded in a warped bulk
geometry, and it is shown to be independent of the number of compact or
non-compact extra dimensions.


title: Universal coding for classical-quantum channel

abstract:
  We construct a universal code for stationary and memoryless classical-quantum
channel as a quantum version of the universal coding by Csisz\'{a}r and
K\"{o}rner. Our code is constructed by the combination of irreducible
representation, the decoder introduced through quantum information spectrum,
and the packing lemma.


title: E-Courant algebroids

abstract:
  In this paper, we introduce the notion of $E$-Courant algebroids, where $E$
is a vector bundle. It is a kind of generalized Courant algebroid and contains
Courant algebroids, Courant-Jacobi algebroids and omni-Lie algebroids as its
special cases. We explore novel phenomena exhibited by $E$-Courant algebroids
and provide many examples. We study the automorphism groups of omni-Lie
algebroids and classify the isomorphism classes of exact $E$-Courant
algebroids. In addition, we introduce the concepts of $E$-Lie bialgebroids and
Manin triples.


title:
Strong coupling of light with one-dimensional quantum dot chain: from
  Rabi oscillations to Rabi waves

abstract:
  Interaction of traveling wave of classic light with 1D-chain of coupled
quantum dots (QDs) in strong coupling regime has been theoretically considered.
The effect of space propagation of Rabi oscillations in the form of traveling
waves and wave packets has been predicted. Physical interpretation of the
effect has been given, principles of its experimental observation are
discussed.


title: Non-volatile switching in graphene field effect devices

abstract:
  The absence of a band gap in graphene restricts its straight forward
application as a channel material in field effect transistors. In this letter,
we report on a new approach to engineer a band gap in graphene field effect
devices (FED) by controlled structural modification of the graphene channel
itself. The conductance in the FEDs is switched between a conductive "on-state"
to an insulating "off-state" with more than six orders of magnitude difference
in conductance. Above a critical value of an electric field applied to the FED
gate under certain environmental conditions, a chemical modification takes
place to form insulating graphene derivatives. The effect can be reversed by
electrical fields of opposite polarity or short current pulses to recover the
initial state. These reversible switches could potentially be applied to
non-volatile memories and novel neuromorphic processing concepts.


title: Characters of coinvariants in (1,p) logarithmic models

abstract:
  We investigate induced modules of doublet algebra in (1,p) logarithmic
models. We give fermionic formulas for the characters of induced modules and
coinvariants with respect to different subalgebras calculated in the
irreducible modules. The characters of coinvariants give multiplicities of
projective modules in fusion of induced modules.


title: On superconducting mechanism in the iron-based layered superconductors

abstract:
  It is demonstrated that SC mechanism of doped Fe-based compounds is
characteristic for itinerant electron systems with coexistence of both (e-e)-
and (e-h)-pairing arising due to electron-phonon and Coulomb interactions,
respectively. The higher Tc of the SC transition here (as compared with
conventional (LTSC) BCS-systems without (e-h)-pairing) is a natural consequence
of (e-e)-pairing at the background of high density of states which arises in
the narrow energy range near dielectric-(SDW)-gap (pseudogap) edges due to
removing of electronic states from the energy region of dielectric (SDW) gap
(pseudogap) (already formed at the part of the Fermi surface in the normal
state with onset temperature T* (near the same for corresponding structural
transition) due to (e-h)-pairing). Below Tc the system enters the coexistence
(SC+SDW) state. The SDW formed is incommensurate with lattice and dynamic in
character. The phase diagram for such system is determined: the doping
dependence of the SC gap (and Tc) has a maximum (optimal doping) while the
dielectric (SDW) gap (pseudogap) (and T*) is a decreasing function of doping.
These conclusions follow from detailed analysis of available resistivity and
another data for Fe-based superconductors on the basis of model with partial
dielectrization of electron energy spectra. The picture obtained and
manifestation of two order parameters (SC and SDW) in experiments, first of
all, in threshold phenomena are discussed. The comparison with the case of
cuprates is performed.


title:
Discovery of a peculiar Cepheid-like star towards the northern edge of
  the Small Magellanic Cloud

abstract:
  For seven years, the EROS-2 project obtained a mass of photometric data on
variable stars. We present a peculiar Cepheid-like star, in the direction of
the Small Magellanic Cloud, which demonstrates unusual photometric behaviour
over a short time interval. We report on data of the photometry acquired by the
MARLY telescope and spectroscopy from the EFOSC instrument for this star,
called EROS2 J005135-714459(sm0060n13842), which resembles the unusual Cepheid
HR 7308. The light curve of our target is analysed using the Analysis of
Variance method to determine a pulsational period of 5.5675 days. A fit of
time-dependent Fourier coefficients is performed and a search for proper motion
is conducted. The light curve exhibits a previously unobserved and spectacular
change in both mean magnitude and amplitude, which has no clear theoretical
explanation. Our analysis of the spectrum implies a radial velocity of 104 km
s$^{-1}$ and a metallicity of -0.4$\pm$0.2 dex. In the direction of right
ascension, we measure a proper motion of 17.4$\pm$6.0 mas yr$^{-1}$ using EROS
astrometry, which is compatible with data from the NOMAD catalogue. The nature
of EROS2 J005135-714459(sm0060n13842) remains unclear. For this star, we may
have detected a non-zero proper motion for this star, which would imply that it
is a foreground object. Its radial velocity, pulsational characteristics, and
photometric data, however, suggest that it is instead a Cepheid-like object
located in the SMC. In such a case, it would present a challenge to
conventional Cepheid models.


title:
Signature change from Schutz's canonical quantum cosmology and its
  classical analogue

abstract:
  We study the signature change in a perfect fluid Friedmann-Robertson-Walker
quantum cosmological model. In this work the Schutz's variational formalism is
applied to recover the notion of time. This gives rise to a
Schrodinger-Wheeler-DeWitt equation with arbitrary ordering for the scale
factor. We use the eigenfunctions in order to construct wave packets and
evaluate the time-dependent expectation value of the scale factor which
coincides with the ontological interpretation. We show that these solutions
exhibit signature transitions from a finite Euclidean to a Lorentzian domain.
Moreover, such models are equivalent to a classical system where, besides the
perfect fluid, a repulsive fluid is present.


title: Semidirect product decomposition of Coxeter groups

abstract:
  Let $(W,S)$ be a Coxeter system, let $S=I \dot{\cup} J$ be a partition of $S$
such that no element of $I$ is conjugate to an element of $J$, let
$\widetilde{J}$ be the set of $W_I$-conjugates of elements of $J$ and let
$\widetilde{W}$ be the subgroup of $W$ generated by $\widetilde{J}$. We show
that $W=\widetilde{W} \rtimes W_I$ and that $(\widetilde{W},\widetilde{J})$ is
a Coxeter system.


title:
Goal-oriented Dialog as a Collaborative Subordinated Activity involving
  Collective Acceptance

abstract:
  Modeling dialog as a collaborative activity consists notably in specifying
the content of the Conversational Common Ground and the kind of social mental
state involved. In previous work (Saget, 2006), we claim that Collective
Acceptance is the proper social attitude for modeling Conversational Common
Ground in the particular case of goal-oriented dialog. In this paper, a
formalization of Collective Acceptance is shown, besides elements in order to
integrate this attitude in a rational model of dialog are provided; and
finally, a model of referential acts as being part of a collaborative activity
is presented. The particular case of reference has been chosen in order to
exemplify our claims.


title:
Effective Hamiltonian approach to the Kerr nonlinearity in an
  optomechanical system

abstract:
  Using the Born-Oppenheimer approximation, we derive an effective Hamiltonian
for an optomechanical system that leads to a nonlinear Kerr effect in the
system's vacuum. The oscillating mirror at one edge of the optomechanical
system induces a squeezing effect in the intensity spectrum of the cavity
field. A near-resonant laser field is applied at the other edge to drive the
cavity field, in order to enhance the Kerr effect. We also propose a
quantum-nondemolition-measurement setup to monitor a system with two cavities
separated by a common oscillating mirror, based on our effective Hamiltonian
approach.


title:
Charge and magnetic order in the spin-one-half Falicov-Kimball model
  with Hund coupling in two dimensions

abstract:
  The spin-one-half Falicov-Kimball model with spin-dependent on-site
interaction between localized ($f$) and itinerant ($d$) electrons is studied by
small-cluster exact-diagonalization calculations and a well-controlled
approximative method in two dimensions. The results obtained are used to
categorize the ground-state configurations according to common features (charge
and spin ordering) for all $f$ and $d$ electron concentrations ($n_f$ and
$n_d$) on finite square lattices. It is shown that only a few configuration
types form the basic structure of the charge phase diagram in the $n_f-n_d$
plane. In particular, the largest regions of stability correspond to the phase
segregated configurations, the axial striped configurations and configurations
that can be considered as mixtures of chessboard configurations and the full
(empty) lattice. Since the magnetic phase diagram is much richer than the
charge phase diagram, the magnetic superstructures are examined only at
selected values of $f$ and $d$ electron concentrations.


title: Evidence for Luminosity Evolution of Long Gamma-ray Bursts in Swift Data

abstract:
  We compute the luminosity function (LF) and the formation rate of long gamma
ray bursts (GRBs) by fitting the observed differential peak flux distribution
obtained by the BATSE experiment in two different scenarios: i) the GRB
luminosity evolves with redshift and ii) GRBs form preferentially in
low-metallicity environments. In both cases, model predictions are consistent
with the Swift number counts and with the number of detections at z>2.5 and
z>3.5. To discriminate between the two evolutionary scenarios, we compare the
model results with the number of luminous bursts (i.e. with isotropic peak
luminosity in excess of 10^53 erg s^-1) detected by Swift in its first three
years of mission. Our sample conservatively contains only bursts with good
redshift determination and measured peak energy. We find that pure luminosity
evolution models can account for the number of sure identifications. In the
case of a pure density evolution scenario, models with Z_th>0.3 Zsun are ruled
out with high confidence. For lower metallicity thresholds, the model results
are still statistically consistent with available lower limits. However, many
factors can increase the discrepancy between model results and data, indicating
that some luminosity evolution in the GRB LF may be needed also for such low
values of Z_th. Finally, using these new constraints, we derive robust upper
limits on the bright-end of the GRB LF, showing that this cannot be steeper
than ~2.6.


title: Fermi surface nesting in several transition metal dichalcogenides

abstract:
  By means of high-resolution angle resolved photoelectron spectroscopy (ARPES)
we have studied the fermiology of 2H transition metal dichalcogenide polytypes
TaSe2, NbSe2, and Cu0.2NbS2. The tight-binding model of the electronic
structure, extracted from ARPES spectra for all three compounds, was used to
calculate the Lindhard function (bare spin susceptibility), which reflects the
propensity to charge density wave (CDW) instabilities observed in TaSe2 and
NbSe2. We show that though the Fermi surfaces of all three compounds possess an
incommensurate nesting vector in the close vicinity of the CDW wave vector, the
nesting and ordering wave vectors do not exactly coincide, and there is no
direct relationship between the magnitude of the susceptibility at the nesting
vector and the CDW transition temperature. The nesting vector persists across
the incommensurate CDW transition in TaSe2 as a function of temperature despite
the observable variations of the Fermi surface geometry in this temperature
range. In Cu0.2NbS2 the nesting vector is present despite different doping
level, which lets us expect a possible enhancement of the CDW instability with
Cu-intercalation in the CuxNbS2 family of materials.


title:
On the uniqueness of the infinite cluster of the vacant set of random
  interlacements

abstract:
  We consider the model of random interlacements on $\mathbb{Z}^d$ introduced
in Sznitman [Vacant set of random interlacements and percolation (2007)
preprint]. For this model, we prove the uniqueness of the infinite component of
the vacant set. As a consequence, we derive the continuity in $u$ of the
probability that the origin belongs to the infinite component of the vacant set
at level $u$ in the supercritical phase $u<u_*$.


title:
Spiral Walk on Triangular Meshes : Adaptive Replication in Data P2P
  Networks

abstract:
  We introduce a decentralized replication strategy for peer-to-peer file
exchange based on exhaustive exploration of the neighborhood of any node in the
network. The replication scheme lets the replicas evenly populate the network
mesh, while regulating the total number of replicas at the same time. This is
achieved by self adaptation to entering or leaving of nodes. Exhaustive
exploration is achieved by a spiral walk algorithm that generates a number of
messages linearly proportional to the number of visited nodes. It requires a
dedicated topology (a triangular mesh on a closed surface). We introduce
protocols for node connection and departure that maintain the triangular mesh
at low computational and bandwidth cost. Search efficiency is increased using a
mechanism based on dynamically allocated super peers. We conclude with a
discussion on experimental validation results.


title: Ternary cluster decay within the liquid drop model

abstract:
  Longitudinal ternary and binary fission barriers of $^{36}$Ar, $^{56}$Ni and
$^{252}$Cf nuclei have been determined within a rotational liquid drop model
taking into account the nuclear proximity energy. For the light nuclei the
heights of the ternary fission barriers become competitive with the binary ones
at high angular momenta since the maximum lies at an outer position and has a
much higher moment of inertia.


title:
Influence of gas flow rate on liquid distribution in trickle-beds using
  perforated plates as liquid distributors

abstract:
  Two wire mesh tomography devices and a liquid collector were used to study
the influence of the gas flow rate on liquid distribution when fluids
distribution on top of the reactor is ensured by a perforated plate. In
opposition to most of the studies realized by other authors, conditions in
which the gas has a negative impact in liquid distribution were evidenced.
Indeed, the obtained results show that the influence of gas flow rate depends
on the quality of the initial distribution, as the gas forces the liquid to
"respect" the distribution imposed at the top of the reactor. Finally, a
comparison between the two measuring techniques shows the limitations of the
liquid collector and the improper conclusions to which its use could lead.


title: Parton picture for the strongly coupled SYM plasma

abstract:
  Deep inelastic scattering off the strongly coupled N=4 supersymmetric
Yang-Mills plasma at finite temperature can be computed within the AdS/CFT
correspondence, with results which are suggestive of a parton picture for the
plasma. Via successive branchings, essentially all partons cascade down to very
small values of the longitudinal momentum fraction x and to transverse momenta
smaller than the saturation momentum Q_s\sim T/x. This scale Q_s controls the
plasma interactions with a hard probe, in particular, the jet energy loss and
its transverse momentum broadening.


title: The 2006 November outburst of EG Aquarii: the SU UMa nature revealed

abstract:
  We report time-resolved CCD photometry of the cataclysmic variable EG Aquarii
during the 2006 November outburst During the outburst, superhumps were
unambiguously detected with a mean period of 0.078828(6) days, firstly
classifying the object as an SU UMa-type dwarf nova. It also turned out that
the outburst contained a precursor. At the end of the precursor, immature
profiles of humps were observed. By a phase analysis of these humps, we
interpreted the features as superhumps. This is the second example that the
superhumps were shown during a precursor. Near the maximum stage of the
outburst, we discovered an abrupt shift of the superhump period by ${\sim}$
0.002 days. After the supermaximum, the superhump period decreased at the rate
of $\dot{P}/P$=$-8.2{\times}10^{-5}$, which is typical for SU UMa-type dwarf
novae. Although the outburst light curve was characteristic of SU UMa-type
dwarf novae, long-term monitoring of the variable shows no outbursts over the
past decade. We note on the basic properties of long period and inactive SU
UMa-type dwarf novae.


title: On the entropy and log-concavity of compound Poisson measures

abstract:
  Motivated, in part, by the desire to develop an information-theoretic
foundation for compound Poisson approximation limit theorems (analogous to the
corresponding developments for the central limit theorem and for simple Poisson
approximation), this work examines sufficient conditions under which the
compound Poisson distribution has maximal entropy within a natural class of
probability measures on the nonnegative integers. We show that the natural
analog of the Poisson maximum entropy property remains valid if the measures
under consideration are log-concave, but that it fails in general. A parallel
maximum entropy result is established for the family of compound binomial
measures. The proofs are largely based on ideas related to the semigroup
approach introduced in recent work by Johnson for the Poisson family.
Sufficient conditions are given for compound distributions to be log-concave,
and specific examples are presented illustrating all the above results.


title: Chaplygin gas in decelerating DGP gravity and the age of the oldest star

abstract:
  Accelerating Chaplygin gas combined with the decelerating braneworld
Dvali-Gabadadze-Porrati (DGP) model can produce an overall accelerated
expansion of the order of magnitude seen. Both models have similar asymptotic
properties at early and late cosmic times, and are characterized by a length
scale. Taking the length scales to be proportional one obtains a combined model
with three free parameters, one more than the LCDM model, which fits supernovae
data equally well. We further constrain it by the CMB shift parameter, and by
requiring that the model yields a longer age of the Universe than that of the
oldest star HE 1523-0901, t * = 13.4\pm 0.8(stat)\pm 1.8(syst). In contrast to
generalized DGP and Chaplygin gas models, this is a genuine alternative to the
cosmological constant model because it does not reduce to it in any limit of
the parameter space.


title: A theorem of Tits type for compact Kahler manifolds

abstract:
  We prove a theorem of Tits type about automorphism groups for compact Kahler
manifolds, which has been conjectured in the paper [KOZ].


title: Transverse Energy Measurement in Au+Au Collisions by the STAR Experiment

abstract:
  Transverse energy ($E_T$) has been measured with both of its components,
namely hadronic ($E_T^{had}$) and electromagnetic ($E_T^{em}$) in a common
phase space at mid-rapidity for 62.4 GeV Au+Au collisions by the STAR
experiment. $E_T$ production with centrality and $\sqrt{s_{NN}}$ is studied
with similar measurements from SPS to RHIC and is compared with a final state
gluon saturation model (EKRT). The most striking feature is the observation of
a nearly constant value of $E_T/N_{ch} \sim 0.8$ GeV from AGS, SPS to RHIC. The
initial energy density estimated by the boost-invariant Bjorken hydrodynamic
model, is well above the critical density for a deconfined matter of quarks and
gluons predicted by lattice QCD calculations.


title:
Mapping of shape invariant potentials by the point canonical
  transformation

abstract:
  In this paper by using the method of point canonical transformation we find
that the Coulomb and Kratzer potentials can be mapped to the Morse potential.
Then we show that the P\"{o}schl-Teller potential type I belongs to the same
subclass of shape invariant potentials as Hulth\'{e}n potential. Also we show
that the shape-invariant algebra for Coulomb, Kratzer, and Morse potentials is
SU(1,1), while the shape-invariant algebra for P\"{o}schl-Teller type I and
Hulth\'{e}n is SU(2).


title:
Recoil collisions as a portal to field assisted ionization at near-UV
  frequencies in the Strong Field Double Ionization of Helium

abstract:
  We explore the dependence of the double ionization of the He atom on the
frequency of a strong laser field while keeping the ponderomotive energy
constant. As we increase the frequency we find that the remarkable
"finger-like" structure for high momenta recently found for $\omega=0.055$ a.u.
\cite{Staudte, Rudenko} persists for higher frequencies. At the same time, at
$\omega=0.187$ a.u. a new X-shape structure emerges for small momenta that
prevails in the correlated momenta distribution. The role of this structure as
a signature of the frequency dependence of non-sequential double ionization is
discussed.


title:
Fluctuations and skewness of the current in the partially asymmetric
  exclusion process

abstract:
  We use functional Bethe Ansatz equations to calculate the cumulants of the
total current in the partially asymmetric exclusion process. We recover known
formulas for the first two cumulants (mean value of the current and diffusion
constant) and obtain an explicit finite size formula for the third cumulant.
The expression for the third cumulant takes a simple integral form in the limit
where the asymmetry scales as the inverse of the square root of the size of the
system, which corresponds to a natural separation between weak and strong
asymmetry.


title:
Electroweak Corrections to the Charm Quark Contribution to K+ -> pi+ nu
  nu-bar

abstract:
  We compute the leading-log QED, the next-to-leading-log QED-QCD, and the
electroweak corrections to the charm quark contribution relevant for the rare
decay K+ -> pi+ nu nu-bar. The corresponding parameter P_c(X) is increased by
up to 2% with respect to the pure QCD estimate to P_c(X) = 0.372 +- 0.015 for
m_c(m_c)= (1.286 +- 0.013) GeV, alphas(M_Z) = 0.1176 +- 0.0020 and |V_us| =
0.2255. For the branching ratio we find B(K+ -> pi+ nu nu-bar) = (8.5 +-
0.7)*10^{-11}, where the quoted uncertainty is dominated by the CKM elements.


title: Mixed Volume Techniques for Embeddings of Laman Graphs

abstract:
  Determining the number of embeddings of Laman graph frameworks is an open
problem which corresponds to understanding the solutions of the resulting
systems of equations. In this paper we investigate the bounds which can be
obtained from the viewpoint of Bernstein's Theorem. The focus of the paper is
to provide the methods to study the mixed volume of suitable systems of
polynomial equations obtained from the edge length constraints. While in most
cases the resulting bounds are weaker than the best known bounds on the number
of embeddings, for some classes of graphs the bounds are tight.


title: Mixing angles of quarks and leptons in Quantum Field Theory

abstract:
  Arguments coming from Quantum Field Theory are supplemented with a 1-loop
perturbative calculation to settle the non-unitarity of mixing matrices linking
renormalized mass eigenstates to bare flavor states for non-degenerate coupled
fermions. We simultaneously diagonalize the kinetic and mass terms and
counterterms in the renormalized Lagrangian. SU(2)_L gauge invariance
constrains the mixing matrix in charged currents of renormalized mass states,
for example the Cabibbo matrix, to stay unitary. Leaving aside CP violation, we
observe that the mixing angles exhibit, within experimental uncertainty, a very
simple breaking pattern of SU(2)_f horizontal symmetry linked to the algebra of
weak neutral currents, the origin of which presumably lies beyond the Standard
Model. It concerns: on one hand, the three quark mixing angles; on the other
hand, a neutrino-like pattern in which theta_{23} is maximal and tan(2
theta_{12})=2. The Cabibbo angle fulfills the condition tan (2 theta_c)=1/2 and
theta_{12} for neutrinos satisfies accordingly the "quark-lepton
complementarity condition" theta_c + theta_{12}= \pi/4. theta_{13} = +- 5.7
10^{-3} are the only values obtained for the third neutrino mixing angle that
lie within present experimental bounds. Flavor symmetries, their breaking by a
non-degenerate mass spectrum, and their entanglement with the gauge symmetry,
are scrutinized; the special role of flavor rotations as a very mildly
brokensymmetry of the Standard Model is outlined.


title:
Boundedness of Fourier integral operators on Fourier Lebesgue spaces and
  affine fibrations

abstract:
  We carry on the study of Fourier integral operators of H{\"o}rmander's type
acting on the spaces $(\mathcal{F}L^p)_{comp}$, $1\leq p\leq\infty$, of
compactly supported distributions whose Fourier transform is in $L^p$. We show
that the sharp loss of derivatives for such an operator to be bounded on these
spaces is related to the rank $r$ of the Hessian of the phase $\Phi(x,\eta)$
with respect to the space variables $x$. Indeed, we show that operators of
order $m=-r|1/2-1/p|$ are bounded on $(\mathcal{F}L^p)_{comp}$, if the mapping
$x\longmapsto\nabla_x\Phi(x,\eta)$ is constant on the fibers, of codimension
$r$, of an affine fibration.


title: Understanding the Very High-Energy Emission from Microquasars

abstract:
  Microquasars are X-ray binaries with relativistic jets. These jets are
powerful energy carriers, thought to be fed by accretion, which produce
non-thermal emission at different energy bands. To date, several Galactic
sources showing extended radio emission, among them at least one confirmed
microquasar, Cygnus X-1, have been detected in the TeV range. All of them show
complex patterns of spectral and temporal behavior. In this work, we discuss
the physics behind the very high-energy emission in microquasars. In concrete,
we focus on the microquasar Cygnus X-1, and also in the other two TeV binaries
with detected extended outflows, LS 5039 and LS I +61 303, pointing out
relevant aspects of the complex phenomena occurring in them. We conclude that
the TeV emission is likely of leptonic origin, although hadrons cannot be
discarded. In addition, efficient electromagnetic cascades can hardly develop
since even relatively low magnetic fields suppress them. Also, the modeling of
the radiation from some of the detected sources points to them as either
extremely efficient accelerators, and/or having the TeV emitter at a distance
from the compact object of about 10e12 cm. Finally, we point out that the role
of a massive and hot stellar companion, due to its strong photon field and
wind, cannot be neglected when trying to understand the behavior of
microquasars at high and very high energies. The complexity of microquasars
precludes straightforward generalizations to a whole population, and are better
studied presently in a source by source base.


title:
XMM-Newton observations of the low-mass X-ray binary XB1832-330 in the
  galactic globular cluster NGC 6652

abstract:
  We report on two XMM-Newton observations performed in 2006 of the luminous
low-mass X-ray binary XB1832-330 which is located in the galactic globular
cluster NGC 6652 and is probably an ultracompact binary (orbital period less
than 1 hour). The aim of these observations is to investigate the low-energy
absorption towards NGC6652 and in particular to search for Ne-rich material
local to the binary, which has been suggested as a possible spectral signature
of Neon rich degenerate companions. XMM-Newton observed the source twice, in
2006 September and October. High resolution spectroscopy with the RGS was used
to estimate the ratio of the neutral neon to oxygen column densities to search
for an anomalous Ne abundance in this X-ray binary. We find no evidence for
anomalous Ne/O ratios, finding Ne/O=0.18+/-0.06 and Ne/O=0.17+/-0.03 (1 sigma
uncertainties), in the two observations, respectively. These values are
consistent with that in the interstellar medium. Timing analysis of EPIC data
suggests possible periodicities at 9170+/-235 s and 18616 +/- 531 s, which need
confirmation. A by-product of these observations consists of the spatial
analysis of the source field, which resulted in the detection of 46 faint
sources within the EPIC field of view, which are not present in the Second
XMM-Newton Serendipitous Source Catalogue. All these faint sources are likely
foreground objects. We performed the first high spectral resolution
observations of XB1832-33, a probable ultracompact binary, without finding any
evidence for an anomalous Ne abundance.


title: Reduced measures associated to parabolic problems

abstract:
  We study the existence and the properties of the reduced measures for the
parabolic equations $\partial_tu-\Delta u+g(u)=0$ in $\Omega\times (0,\infty)$
subject to the conditions ($P$): $u=0$ on $\partial\Omega\times (0,\infty)$,
$u(x,0)=\mu$ and ($P'$): $u=\mu'$ on $\partial\Omega\times (0,\infty)$,
$u(x,0)=0$ where $\mu$ and $\mu'$ are positive Radon measures and $g$ a
continuous nondecreasing function


title: On rational normal curves in projective space

abstract:
  In this paper we consider a generalization of a well known result by Veronese
about rational normal curves. More precisely, given a collection of linear
spaces in $\PP^n$ we study the existence of rational normal curves intersecting
each component of the configuration maximally. We introduce different methods
to show existence and non-existence of such curves. We also show how to apply
these techniques to the study of defectivity of Segre-Veronese varieties.


title:
Ultra accurate personalized recommendation via eliminating redundant
  correlations

abstract:
  In this paper, based on a weighted projection of bipartite user-object
network, we introduce a personalized recommendation algorithm, called the
\emph{network-based inference} (NBI), which has higher accuracy than the
classical algorithm, namely \emph{collaborative filtering}. In the NBI, the
correlation resulting from a specific attribute may be repeatedly counted in
the cumulative recommendations from different objects. By considering the
higher order correlations, we design an improved algorithm that can, to some
extent, eliminate the redundant correlations. We test our algorithm on two
benchmark data sets, \emph{MovieLens} and \emph{Netflix}. Compared with the
NBI, the algorithmic accuracy, measured by the ranking score, can be further
improved by 23% for \emph{MovieLens} and 22% for \emph{Netflix}, respectively.
The present algorithm can even outperform the \emph{Latent Dirichlet
Allocation} algorithm, which requires much longer computational time.
Furthermore, most of the previous studies considered the algorithmic accuracy
only, in this paper, we argue that the diversity and popularity, as two
significant criteria of algorithmic performance, should also be taken into
account. With more or less the same accuracy, an algorithm giving higher
diversity and lower popularity is more favorable. Numerical results show that
the present algorithm can outperform the standard one simultaneously in all
five adopted metrics: lower ranking score and higher precision for accuracy,
larger Hamming distance and lower intra-similarity for diversity, as well as
smaller average degree for popularity.


title: Convergence of Point Processes with Weakly Dependent Points

abstract:
  For each $n \geq 1$, let $\{X_{j,n}\}_{1 \leq j \leq n}$ be a sequence of
strictly stationary random variables. In this article, we give some asymptotic
weak dependence conditions for the convergence in distribution of the point
process $N_n=\sum_{j=1}^{n}\delta_{X_{j,n}}$ to an infinitely divisible point
process. From the point process convergence, we obtain the convergence in
distribution of the partial sum sequence $S_n=\sum_{j=1}^{n}X_{j,n}$ to an
infinitely divisible random variable, whose L\'{e}vy measure is related to the
canonical measure of the limiting point process. As examples, we discuss the
case of triangular arrays which possess known (row-wise) dependence structures,
like the strong mixing property, the association, or the dependence structure
of a stochastic volatility model.


title: Spin-polaron band structure and hole pockets in underdoped cuprates

abstract:
  We present a variational approach based on the string picture to analyze the
internal structure and dispersion of spin polarons with different symmetries in
an antiferromagnet. We then use this to discuss the properties of underdoped
cuprate superconductor within the `doped insulator' picture. The theory
explains the remnant Fermi surface for the undoped compunds, as well as hole
pockets, Fermi arcs, high energy pseudogap and the the mid-infrared band in
doped materials. Destructive interference between the phases of a photohole
near $\Gamma$ and the internal phases of the Zhang Rice singlet combined with
our theory moreover explains the `waterfall' phenomenon.


title: Towards a Theory of Chaos Explained as Travel on Riemann Surfaces

abstract:
  This paper presents a more complete version than hitherto published of our
explanation of a transition from regular to irregular motions and more
generally of the nature of a certain kind of deterministic chaos. To this end
we introduced a simple model analogous to a three-body problem in the plane,
whose general solution is obtained via quadratures all performed in terms of
elementary functions. For some values of the coupling constants the system is
isochronous and explicit formulas for the period of the solutions can be given.
For other values, the motions are confined but feature aperiodic (in some sense
chaotic) motions.
  This rich phenomenology can be understood in remarkable, quantitative detail
in terms of travel on a certain (circular) path on the Riemann surfaces defined
by the solutions of a related model considered as functions of a complex time.
This model is meant to provide a paradigmatic first step towards a somewhat
novel understanding of a certain kind of chaotic phenomena.


title: Stability of projective Poincare and Picard bundles

abstract:
  Let $X$ be an irreducible smooth projective curve of genus $g\ge3$ defined
over the complex numbers and let ${\mathcal M}_\xi$ denote the moduli space of
stable vector bundles on $X$ of rank $n$ and determinant $\xi$, where $\xi$ is
a fixed line bundle of degree $d$. If $n$ and $d$ have a common divisor, there
is no universal vector bundle on $X\times {\mathcal M}_\xi$. We prove that
there is a projective bundle on $X\times {\mathcal M}_\xi$ with the property
that its restriction to $X\times\{E\}$ is isomorphic to $P(E)$ for all
$E\in\mathcal{M}_\xi$ and that this bundle (called the projective Poincar\'e
bundle) is stable with respect to any polarization; moreover its restriction to
$\{x\}\times\mathcal{M}_\xi$ is also stable for any $x\in X$. We prove also
stability results for bundles induced from the projective Poincar\'e bundle by
homomorphisms $\text{PGL}(n)\to H$ for any reductive $H$. We show further that
there is a projective Picard bundle on a certain open subset $\mathcal{M}'$ of
$\mathcal{M}_\xi$ for any $d>n(g-1)$ and that this bundle is also stable. We
obtain new results on the stability of the Picard bundle even when $n$ and $d$
are coprime.


title: The relative power and its invariance

abstract:
  The relative power of actions in a Cauchy body suffering mutations due to
defect evolution is introduced. It is shown that its invariance under the
action of the Euclidean group over the ambient space and the material space
allows one to obtain (i) the balance of standard and configurational actions
and (ii) the identification of configurational ingredients from a unique
source.


title: Poisson Cloning Model for Random Graphs

abstract:
  In the random graph $G(n,p)$ with $pn$ bounded, the degrees of the vertices
are almost i.i.d Poisson random variables with mean $\gl:= p(n-1)$. Motivated
by this fact, we introduce the Poisson cloning model $G_{PC} (n,p)$ for random
graphs in which the degrees are i.i.d Poisson random variables with mean $\gl$.
Then, we first establish a theorem that shows the new model is equivalent to
the classical model $G(n,p)$ in an asymptotic sense. Next, we introduce a
useful algorithm, called the cut-off line algorithm, to generate the random
graph $G_{PC} (n,p)$. The Poisson cloning model $G_{PC}(n,p)$ equipped with the
cut-off line algorithm enables us to very precisely analyze the sizes of the
largest component and the $t$-core of $G(n,p)$. This new approach to the
problems yields not only elegant proofs but also improved bounds that are
essentially best possible. We also consider the Poisson cloning models for
random hypergraphs and random $k$-SAT problems. Then, the $t$-core problem for
random hypergraphs and the pure literal algorithm for random $k$-SAT problems
are analyzed.


title: Design and Implementation Aspects of a novel Java P2P Simulator with GUI

abstract:
  Peer-to-peer networks consist of thousands or millions of nodes that might
join and leave arbitrarily. The evaluation of new protocols in real
environments is many times practically impossible, especially at design and
testing stages. The purpose of this paper is to describe the implementation
aspects of a new Java based P2P simulator that has been developed to support
scalability in the evaluation of such P2P dynamic environments. Evolving the
functionality presented by previous solutions, we provide a friendly graphical
user interface through which the high-level theoretic researcher/designer of a
P2P system can easily construct an overlay with the desirable number of nodes
and evaluate its operations using a number of key distributions. Furthermore,
the simulator has built-in ability to produce statistics about the distributed
structure. Emphasis was given to the parametrical configuration of the
simulator. As a result the developed tool can be utilized in the simulation and
evaluation procedures of a variety of different protocols, with only few
changes in the Java code.


title:
La th\'eorie des invariants des formes quadratiques ternaires
  revisit\'ee

abstract:
  The simultaneous invariants of 2, 3, 4 and 5 ternary quadratic forms under
the group $\SL(3, {\Bbb C})$ were given by several authors (P. Gordan, C.
Ciamberlini, H.W. Turnbull, J.A Todd), utilizing the symbolic method. Using the
Jordan algebra structure of the space of ternary quadratic forms, we give these
invariants explicitely.


title:
Inference for the dark energy equation of state using Type IA supernova
  data

abstract:
  The surprising discovery of an accelerating universe led cosmologists to
posit the existence of "dark energy"--a mysterious energy field that permeates
the universe. Understanding dark energy has become the central problem of
modern cosmology. After describing the scientific background in depth, we
formulate the task as a nonlinear inverse problem that expresses the comoving
distance function in terms of the dark-energy equation of state. We present two
classes of methods for making sharp statistical inferences about the equation
of state from observations of Type Ia Supernovae (SNe). First, we derive a
technique for testing hypotheses about the equation of state that requires no
assumptions about its form and can distinguish among competing theories.
Second, we present a framework for computing parametric and nonparametric
estimators of the equation of state, with an associated assessment of
uncertainty. Using our approach, we evaluate the strength of statistical
evidence for various competing models of dark energy. Consistent with current
studies, we find that with the available Type Ia SNe data, it is not possible
to distinguish statistically among popular dark-energy models, and that, in
particular, there is no support in the data for rejecting a cosmological
constant. With much more supernova data likely to be available in coming years
(e.g., from the DOE/NASA Joint Dark Energy Mission), we address the more
interesting question of whether future data sets will have sufficient
resolution to distinguish among competing theories.


title: Some open questions in "wave chaos"

abstract:
  The subject area referred to as "wave chaos", "quantum chaos" or "quantum
chaology" has been investigated mostly by the theoretical physics community in
the last 30 years. The questions it raises have more recently also attracted
the attention of mathematicians and mathematical physicists, due to connections
with number theory, graph theory, Riemannian, hyperbolic or complex geometry,
classical dynamical systems, probability etc. After giving a rough account on
"what is quantum chaos?", I intend to list some pending questions, some of them
having been raised a long time ago, some others more recent.


title:
Algebras with involution that become hyperbolic over the fonction field
  of a conic

abstract:
  We study central simple algebras with involution of the first kind that
become hyperbolic over the function field of the conic associated to a given
quaternion algebra $Q$. We classify these algebras in degree~4 and give an
example of such a division algebra with orthogonal involution of degree~8 that
does not contain $Q$ with its canonical involution, even though it contains $Q$
and is totally decomposable into a tensor product of quaternion algebras with
involution.


title: Hydrogen-induced metallization of the $\beta$-SiC(001) Si-rich surface

abstract: This paper has been withdrawn by the authors (see text).


title: Cohomologically hyperbolic endomorphisms of complex manifolds

abstract:
  We show that if a compact Kahler manifold X admits a cohomologically
hyperbolic surjective endomorphism then its Kodaira dimension is non-positive.
This gives an affirmative answer to a conjecture of Guedj in the holomorphic
case. The main part of the paper is to determine the geometric structure and
the fundamental groups (up to finite index) for those X of dimension 3.


title: On the path density of a gradient field

abstract:
  We consider the problem of reliably finding filaments in point clouds.
Realistic data sets often have numerous filaments of various sizes and shapes.
Statistical techniques exist for finding one (or a few) filaments but these
methods do not handle noisy data sets with many filaments. Other methods can be
found in the astronomy literature but they do not have rigorous statistical
guarantees. We propose the following method. Starting at each data point we
construct the steepest ascent path along a kernel density estimator. We locate
filaments by finding regions where these paths are highly concentrated.
Formally, we define the density of these paths and we construct a consistent
estimator of this path density.


title: Scattering of backward spin waves in a one-dimensional magnonic crystal

abstract:
  Scattering of backward volume magnetostatic spin waves from a one-dimensional
magnonic crystal, realized by a grating of shallow grooves etched into the
surface of an yttrium-iron garnet film, was experimentally studied. Rejection
frequency bands were clearly observed. The rejection efficiency and the
frequency width of the rejection bands increase with increasing groove depth. A
theoretical model based on the analogy of a spin-wave film-waveguide with a
microwave transmission line was used to interpret the obtained experimental
results.


title:
Mesoscopic fluctuations in the spin-electric susceptibility due to
  Rashba spin-orbit interaction

abstract:
  We investigate mesoscopic fluctuations in the spin polarization generated by
a static electric field and by Rashba spin-orbit interaction in a disordered 2D
electron gas. In a diagrammatic approach we find that the out-of-plane
polarization -- while being zero for self-averaging systems -- exhibits large
sample-to-sample fluctuations which are shown to be well within experimental
reach. We evaluate the disorder-averaged variance of the susceptibility and
find its dependence on magnetic field, spin-orbit interaction, dephasing, and
chemical potential difference.


title: Stokes Theorem for Lipschitz forms on a smooth manifold

abstract: Stokes theorem holds for Lipschitz forms on a smooth manifold.


title: From Euclidean to Minkowski space with the Cauchy-Riemann equations

abstract:
  We present an elementary method to obtain Green's functions in
non-perturbative quantum field theory in Minkowski space from calculated
Green's functions in Euclidean space. Since in non-perturbative field theory
the analytical structure of amplitudes is many times unknown, especially in the
presence of confined fields, dispersive representations suffer from systematic
uncertainties. Therefore we suggest to use the Cauchy-Riemann equations, that
perform the analytical continuation without assuming global information on the
function in the entire complex plane, only in the region through which the
equations are solved. We use as example the quark propagator in Landau gauge
Quantum Chromodynamics, that is known from lattice and Dyson-Schwinger studies
in Euclidean space. The drawback of the method is the instability of the
Cauchy-Riemann equations to high-frequency noise, that makes difficult to
achieve good accuracy. We also point out a few curiosities related to the Wick
rotation.


title:
Transverse-Longitudinal Emittance Transfer in Circular Accelerators
  Revised

abstract:
  We revise a previous version of this paper proposing a method to transfer
emittances from the transverse planes to the longitudinal. It turned out the
system showed non-Hamiltonian behavior because the longitudinal component of
the transverse electric field at ends of the transverse resonator were not
included in the model. Including those fields the 6D emittance is conserved. We
review the mechanism behind the emittance conservation. It is still possible to
produce an emittance transfer with the RF quadrupole field setting the tunes on
synchro-betatron resonance for a short period of time then reducing the
transverse RF field to zero. We found some coupling between the transverse and
the longitudinal planes is always present, even there in no special device in
the accelerator to provoke it. The role of the transverse RF field is to modify
the transverse tunes quickly putting the system to synchro-betatron resonance
for a short time. The emittance tends to flow from the plane with bigger
emittance to the smaller one.


title: Succinct Geometric Indexes Supporting Point Location Queries

abstract:
  We propose to design data structures called succinct geometric indexes of
negligible space (more precisely, o(n) bits) that, by taking advantage of the n
points in the data set permuted and stored elsewhere as a sequence, to support
geometric queries in optimal time. Our first and main result is a succinct
geometric index that can answer point location queries, a fundamental problem
in computational geometry, on planar triangulations in O(lg n) time. We also
design three variants of this index. The first supports point location using
$\lg n + 2\sqrt{\lg n} + O(\lg^{1/4} n)$ point-line comparisons. The second
supports point location in o(lg n) time when the coordinates are integers
bounded by U. The last variant can answer point location in O(H+1) expected
time, where H is the entropy of the query distribution. These results match the
query efficiency of previous point location structures that use O(n) words or
O(n lg n) bits, while saving drastic amounts of space.
  We then generalize our succinct geometric index to planar subdivisions, and
design indexes for other types of queries. Finally, we apply our techniques to
design the first implicit data structures that support point location in
$O(\lg^2 n)$ time.


title:
The loci of abelian varieties with points of high multiplicity on the
  theta divisor

abstract:
  We study the loci of principally polarized abelian varieties with points of
high multiplicity on the theta divisor. Using the heat equation and
degeneration techniques, we relate these loci and their closures to each other,
as well as to the singular set of the universal theta divisor. We obtain bounds
on the dimensions of these loci and relations among their dimensions, and make
further conjectures about their structure.


title: Complexity of thermal states in quantum spin chains

abstract:
  We study quantum correlations and complexity of simulation, characterized by
quantum mutual information and entanglement entropy in operator space
respectively, for thermal states in critical, non-critical and quantum chaotic
spin chains. A simple general relation between the two quantities is proposed.
We show that in all cases mutual information and entanglement entropy saturate
with the system size, whereas as a function of the inverse temperature, we find
logarithmic divergences for critical cases and uniform bounds in non-critical
cases. A simple efficient quasi-exact method for computation of arbitrary
entropy related quantities in thermalized XY spin chains is proposed.


title: L^2-Invariants of Finite Aspherical CW-Complexes

abstract:
  Let $X$ be a finite aspherical CW-complex whose fundamental group $\pi_1(X)$
possesses a subnormal series $\pi_1(X) \rhd G_m \rhd ... \rhd G_0$ with a
non-trivial elementary amenable group $G_0$. We investigate the
$L^2$-invariants of the universal covering of such a CW-complex $X$. We show
that the Novikov-Shubin invariants $\alpha_n({\tilde X})$ are positive. We
further prove that the $L^2$-torsion $\rho^{(2)}({\tilde X})$ vanishes if
$\pi_1(X)$ has semi-integral determinant.


title: Stationary density matrix of a pumped polariton system

abstract:
  The density matrix, \rho, of a model polariton system is obtained numerically
from a master equation which takes account of pumping and losses. In the
stationary limit, the coherences between eigenstates of the Hamiltonian are
three orders of magnitude smaller than the occupations, meaning that the
stationary density matrix is approximately diagonal in the energy
representation. A weakly distorted grand canonical Gibbs distribution fits well
the occupations.


title: The duty cycle of local radio galaxies

abstract:
  We use a volume- and flux-limited sample of local ($0.03 \leq z \leq 0.1$)
radio galaxies with optical counterparts to address the question of how long a
typical galaxy spends in radio-active and quiescent states. The length of the
active phase has a strong dependence on the stellar mass of the host galaxy.
Radio sources in the most massive hosts are also retriggered more frequently.
The time spent in the active phase has the same dependence on stellar mass as
does the gas cooling rate, suggesting the onset of the quiescent phase is due
to fuel depletion. We find radio and emission line AGN activity to be
independent, consistent with these corresponding to different accretion states.


title: Thermal dileptons at SPS energies

abstract:
  Clear signs of excess dileptons above the known sources were found at the SPS
since long. However, a real clarification of these observations was only
recently achieved by NA60, measuring dimuons with unprecedented precision in
158A GeV, In-In collisions. The excess mass spectrum in the region M<1 GeV is
consistent with a dominant contribution from pi+pi- -> rho -> mu+mu-
annihilation. The associated rho spectral function shows a strong broadening,
but essentially no shift in mass. In the region M>1 GeV, the excess is found to
be prompt, not due to enhanced charm production. The inverse slope parameter
Teff associated with the transverse momentum spectra rises with mass up to the
rho, followed by a sudden decline above. While the initial rise, coupled to a
hierarchy in hadron freeze-out, points to radial flow of a hadronic decay
source, the decline above signals a transition to a low-flow source, presumably
of partonic origin. The mass spectra show at low transverse momenta the steep
rise towards low masses characteristic for Planck-like radiation. The
polarization of the excess referred to the Collins Soper frame is found to be
isotropic. All observations are consistent with the interpretation of the
excess as thermal radiation.


title:
On The Dependence Structure of Wavelet Coefficients for Spherical Random
  Fields

abstract:
  We consider the correlation structure of the random coefficients for a wide
class of wavelet systems on the sphere (Mexican needlets) which were recently
introduced in the literature by Geller and Mayeli (2007). We provide necessary
and sufficient conditions for these coefficients to be asymptotic uncorrelated
in the real and in the frequency domain. Here, the asymptotic theory is
developed in the high resolution sense. Statistical applications are also
discussed, in particular with reference to the analysis of cosmological data.

categories: math.ST astro-ph math.PR stat.ME stat.TH


title: Hypersharp Neutrino Lines

abstract:
  Neutrino lines from very long lived nuclei in simple crystals such as metals
have hypersharp natural width, motionally narrowed by lattice vibrations in
analogy to recoilless emission. A generalized hypersharp line fraction
including the recoilless part can be derived in a frequency modulation
approach. The nue lines of natural width in 3H to 3He 2-body beta-decay can
then be resonantly captured with geometrical cross section. The extreme
sharpness DeltaE/E~10-29 of the tritium nue line can probe the Planck length L
via its limits on the widths of states, DeltaE/E(L) =L(L/R)beta =10-20(beta ~1)
to 10-40 (beta= L/R(fm)). Stringent limits can be set on beta, thus, on models
of quantum gravity.


title:
Neutron Transfer Dynamics and Doorway to Fusion in Time-Dependent
  Hartree-Fock Theory

abstract:
  We analyze the details of mass exchange in the vicinity of the Coulomb
barrier for heavy-ion collisions involving neutron-rich nuclei using the
time-dependent Hartree-Fock (TDHF) theory. We discuss the time-dependence of
transfer and show that the potential barriers seen by individual
single-particle states can be considerably different than the effective barrier
for the two interacting nuclei having a single center-of-mass. For this reason
we observe a substantial transfer probability even at energies below the
effective barrier.


title: Gaussianity

abstract:
  In this chapter we review the present status of the Gaussianity studies of
the CMB anisotropies, including physical effects producing non-Gaussianity,
methods to test it and observational constraints.


title:
Characterisation of radiation damage in silicon photomultipliers with a
  Monte Carlo model

abstract:
  Measured response functions and low photon yield spectra of silicon
photomultipliers (SiPM) were compared to multi-photoelectron pulse-height
distributions generated by a Monte Carlo model. Characteristic parameters for
SiPM were derived. The devices were irradiated with 14 MeV electrons at the
Mainz microtron MAMI. It is shown that the first noticeable damage consists of
an increase in the rate of dark pulses and the loss of uniformity in the pixel
gains. Higher radiation doses reduced also the photon detection efficiency. The
results are especially relevant for applications of SiPM in fibre detectors at
high luminosity experiments.


title: Primordial magnetic fields from preheating at the electroweak scale

abstract:
  We analyze the generation of helical magnetic fields during preheating in a
model of low-scale electroweak (EW) hybrid inflation. We show how the
inhomogeneities in the Higgs field, resulting from tachyonic preheating after
inflation, seed the magnetic fields in a way analogous to that predicted by
Vachaspati and Cornwall in the context of the EW symmetry breaking. At this
stage, the helical nature of the generated magnetic fields is linked to the
non-trivial winding of the Higgs-field. We analyze non-perturbatively the
evolution of these helical seeds through the highly non-linear stages of
symmetry breaking (SB) and beyond. Electroweak SB occurs via the nucleation and
growth of Higgs bubbles which squeeze the magnetic fields into string-like
structures. The W-boson charge density clusters in lumps around the magnetic
strings. After symmetry breaking, a detailed analysis of the magnetic field
Fourier spectrum shows two well differentiated components: a UV radiation tail
at a temperature T ~ 0.23 m_higgs slowly growing with time, and an IR peak
associated to the helical magnetic fields, which seems to follow inverse
cascade. The system enters a regime in which we observe that both the amplitude
(\rho_B/\rho_{EW} ~ 0.01) and the correlation length of the magnetic field grow
linearly with time. During this stage of evolution we also observe a power-law
growth in the helical susceptibility. These properties support the possibility
that our scenario could provide the seeds eventually evolving into the
microgauss fields observed today in galaxies and clusters of galaxies.


title: Kinetic surface roughening for the Mullins-Herring equation

abstract:
  Using the linearity property of the Mullins-Herring equation when the
velocity is zero with a Gaussian noise, we obtain an analytic form for the
global mean-square surface width and height-height correlation function. This
can be used to read the critical exponents in any dimension. In particular for
d=1 we show that although the surface is super rough the system exhibits
Family-Vicsek scaling behavior.


title:
On Homological and Homotopical Algebra of Supersymmetries and
  Integrability in String Theory

abstract:
  The text contains introduction and preliminary definitions and results to my
talk on category theory description of supersymmetries and integrability in
string theory. In the talk I plan to present homological and homotopical
algebra framework for Calabi-Yau supermanifolds and stacks in open and closed
string theory. In the framework we investigate supersymmetries and
integrability.


title:
Flops on holomorphic symplectic fourfolds and determinantal cubic
  hypersurfaces

abstract:
  We study the birational geometry of irreducible holomorphic symplectic
varieties arising as varieties of lines of general cubic fourfolds containing a
cubic scroll. We compute the ample and moving cones, and exhibit a birational
automorphism of infinite order explaining the chamber decomposition of the
moving cone.


title: Need for context-aware computing in astrophysics

abstract:
  The example of disk galaxy rotation curves is given for inferring dark matter
from redundant computational procedure because proper care of astrophysical and
computational context was not taken. At least three attempts that take the
context into account have not found adequate voice because of haste in wrongly
concluding existence of dark matter on the part of even experts. This firmly
entrenched view, prevalent for about 3/4ths of a century, has now become
difficult to correct. The right context must be borne in mind at every step to
avoid such a situation. Perhaps other examples exist. Keywords: dark matter;
disk galaxy; rotation curve; context-awareness. Topics: Algorithms;
Applications.


title: Multimode quantum memory based on atomic frequency combs

abstract:
  An efficient multi-mode quantum memory is a crucial resource for
long-distance quantum communication based on quantum repeaters. We propose a
quantum memory based on spectral shaping of an inhomogeneously broadened
optical transition into an atomic frequency comb (AFC). The spectral width of
the AFC allows efficient storage of multiple temporal modes, without the need
to increase the absorption depth of the storage material, in contrast to
previously known quantum memories. Efficient readout is possible thanks to
rephasing of the atomic dipoles due to the AFC structure. Long-time storage and
on-demand readout is achieved by use of spin-states in a lambda-type
configuration. We show that an AFC quantum memory realized in solids doped with
rare-earth-metal ions could store hundreds of modes or more with close to unit
efficiency, for material parameters achievable today.


title:
Method of determination of the most probable coordinate of formation of
  $\alpha$-particle in $\alpha$-decay

abstract:
  Method of multiple internal reflections (method MIR) in description of
$\alpha$-decay of nucleus in the spherically symmetric approximation is
presented in paper. In approach MIR the formalism of calculation of amplitudes
of wave function, described moving of $\alpha$-particle from the internal
region outside with its tunneling through a realistic radial $\alpha$-nucleus
barrier of arbitrary shape, has been constructed at first time. The method MIR
gives convergent values for the amplitudes of transmission and reflection,
coefficients of penetrability and reflection, obtained in description of
leaving of the $\alpha$-particle relatively a potential with barrier in form of
a number of rectangular steps (multi-steps potential), with tending this
potential to the realistic $\alpha$-nucleus one, and limit values of the
amplitudes and coefficients are considered as exact concerning the realistic
$\alpha$-nucleus potential (without application of WKB approximation). In
approach MIR a dependence of the penetrability coefficient and half-live on the
location of the starting point, from where $\alpha$-particle begins to move
outside, is opened. From here, we define a radial coordinate of the most
probable formation of the $\alpha$-particle inside nucleus before its
$\alpha$-decay as such starting point, at moving of the $\alpha$-particle from
which outside the half-live, calculated by approach MIR, is maximally closed to
its experimental value. For isotopes ${\rm Po}$ with different mass number $A$
we have obtained essentially closer values for half-live, calculated by such
approach, to their experimental values in a comparison with half-lives obtained
by approach WKB. This result is stable for all studied nuclei.


title: Phase space distribution of Gabor expansions

abstract:
  We present an example of a complete and minimal Gabor system consisting of
time-frequency shifts of a Gaussian, localized at the coordinate axes in the
time-frequency plane (phase space). Asymptotically, the number of
time-frequency shifts contained in a disk centered at the origin is only 2/pi
times the number of points from the von Neumann lattice found in the same disk.
Requiring a certain regular distribution in phase space, we show that our
system has minimal density among all complete and minimal systems of
time-frequency shifts of a Gaussian.


title: Environment Assumptions for Synthesis

abstract:
  The synthesis problem asks to construct a reactive finite-state system from
an $\omega$-regular specification. Initial specifications are often
unrealizable, which means that there is no system that implements the
specification. A common reason for unrealizability is that assumptions on the
environment of the system are incomplete. We study the problem of correcting an
unrealizable specification $\phi$ by computing an environment assumption $\psi$
such that the new specification $\psi\to\phi$ is realizable. Our aim is to
construct an assumption $\psi$ that constrains only the environment and is as
weak as possible. We present a two-step algorithm for computing assumptions.
The algorithm operates on the game graph that is used to answer the
realizability question. First, we compute a safety assumption that removes a
minimal set of environment edges from the graph. Second, we compute a liveness
assumption that puts fairness conditions on some of the remaining environment
edges. We show that the problem of finding a minimal set of fair edges is
computationally hard, and we use probabilistic games to compute a locally
minimal fairness assumption.


title: Probability distributions for polymer translocation

abstract:
  We study the passage (translocation) of a self-avoiding polymer through a
membrane pore in two dimensions. In particular, we numerically measure the
probability distribution Q(T) of the translocation time T, and the distribution
P(s,t) of the translocation coordinate s at various times t. When scaled with
the mean translocation time <T>, Q(T) becomes independent of polymer length,
and decays exponentially for large T. The probability P(s,t) is well described
by a Gaussian at short times, with a variance that grows sub-diffusively as
t^{\alpha} with \alpha~0.8. For times exceeding <T>, P(s,t) of the polymers
that have not yet finished their translocation has a non-trivial stable shape.


title: Exact solution for the interior of a black hole

abstract:
  Within the Relativistic Theory of Gravitation it is shown that the equation
of state $p=\rho$ holds near the center of a black hole. For the stiff equation
of state $p=\rho-\rho_c$ the interior metric is solved exactly. It is matched
with the Schwarzschild metric, which is deformed in a narrow range beyond the
horizon. The solution is regular everywhere, with a specific shape at the
origin. The gravitational redshift at the horizon remains finite but is large,
$z\sim 10^{23}$$M_\odot/M$. Time keeps its standard role also in the interior.
The energy of the Schwarzschild metric, shown to be minus infinity in the
General Theory of Relativity, is regularized in this setup, resulting in
$E=Mc^2$.


title: B, Bs -> K form factors: an update of light-cone sum rule results

abstract:
  We present an improved QCD light-cone sum rule (LCSR) calculation of the B ->
K and Bs -> K form factors, by including SU(3)-symmetry breaking corrections.
We use recently updated K-meson distribution amplitudes which incorporate the
complete SU(3)-breaking structure. By applying the method of the direct
integration in the complex plane, which is presented in a detail, the
analytical extraction of the imaginary parts of LCSR hard-scattering amplitudes
becomes unnecessary and therefore the complexity of the calculation is greatly
reduced. The values obtained for the relevant B_{(s)} -> K form factors are as
follows: f^+_{BK}(0)= 0.36^{+0.05}_{-0.04}, f^+_{B_sK}(0)= 0.30^{+0.04}_{-0.03}
and f^T_{BK}(0)= 0.38\pm 0.05, f^T_{B_sK}(0)= 0.30\pm 0.05. By comparing with
the B -> pi form factors extracted recently by the same method, we find the
following SU(3) violation among the B -> light form factors:
f^+_{BK}(0)/f^+_{B\pi}(0) = 1.38^{+0.11}_{-0.10}, f^+_{B_sK}(0)/f^+_{B\pi}(0) =
1.15^{+0.17}_{-0.09}, f^T_{BK}(0)/f^T_{B\pi}(0) = 1.49^{+0.18}_{-0.06} and
f^T_{B_sK}(0)/f^T_{B\pi}(0) = 1.17^{+0.15}_{-0.11}.


title:
Model Independent Tests for Time Reversal and CP Violations and for CPT
  Theorem in \Lambda_b and \bar\Lambda_b Two Body Decays

abstract:
  Weak decays of beauty baryons like \Lambda_b (\bar\Lambda_b) into \Lambda
(\bar\Lambda) and V (J^P = 1^-), where both decay products are polarized, offer
interesting opportunities to perform tests of time reversal and CP violations
and of CPT invariance. We propose a model independent parametrization of the
angular distribution and of the polarization of the final resonances, by means
of the spin density matrix. The transverse component of the polarization is
sensitive to time reversal violations, moreover CP-and CPT-sensitive
observables are defined.


title: The scattering matrix and associated formulas in Hamiltonian mechanics

abstract:
  We survey the basic notions of scattering theory in Hamiltonian mechanics
with a particular attention to the analogies with scattering theory in quantum
mechanics. We discuss the scattering symplectomorphism, which is analogous to
the scattering matrix. We prove identities which relate the Calabi invariant of
the scattering symplectomorphism to the total time delay and the regularised
phase space volume. These identities are analogous to the Birman-Krein formula
and the Eisenbud-Wigner formula in quantum scattering theory.


title: Occurrence of pairwise energy level degeneracies in q,p-oscillator model

abstract:
  It is demonstrated that a two-parameter deformed oscillator with the
deformation parameters q,p such that 0 < q,p \le 1 exhibits the property of
"accidental" two-fold (pairwise) energy level degeneracy of the classes
E_m=E_{m+1} and E_0=E_{m}. The most general case of degeneracy of
q,p-oscillators of the form E_{m+k}=E_m (with k\ge 1 for m\ge 1 or k\ge 2 for
m=0) is briefly discussed.

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


title: On a generalization of Christoffel words: epichristoffel words

abstract:
  Sturmian sequences are well-known as the ones having minimal complexity over
a 2-letter alphabet. They are also the balanced sequences over a 2-letter
alphabet and the sequences describing discrete lines. They are famous and have
been extensively studied since the 18th century. One of the {extensions} of
these sequences over a $k$-letter alphabet, with $k\geq 3$, are the episturmian
sequences, which generalizes a construction of Sturmian sequences using the
palindromic closure operation. There exists a finite version of the Sturmian
sequences called the Christoffel words. They are known since the works of
Christoffel and have interested many mathematicians. In this paper, we
introduce a generalization of Christoffel words for an alphabet with 3 letters
or more, using the episturmian morphisms. We call them the {\it epichristoffel
words}. We define this new class of finite words and show how some of the
properties of the Christoffel words can be generalized naturally or not for
this class.


title: Weight fluctuations of information storage media

abstract:
  In this essentially Unsolved Problems of Noise (UPoN) paper we further study
the question recently posed in Fluctuation and Noise Letters (December 2007),
if there is and interaction between bodies with correlated information content,
and weather the observed weight transients during/after changing the
information content in memory devices is due to a new type of interaction, a
new type of "fifth force", or it is only a classical mechanism. We briefly
discuss the issue of the great experimental uncertainty of the Newtonian
gravitation constant. We also mention the peculiar experiments about sudden
weight changes of humans and animals at the moment of death. The extended
monitoring of four 4GB flash drives with no casing and various information
content indicate a significant correlation between their weight variations and
the fluctuations of ambient humidity. This is an evidence for the role of
humidity and hygroscopic components, at least, for long-term weight
fluctuations. A sequence of information changing experiments with such a flash
drives at stable humidity conditions shows a significant variability of the
transients of the absolute mass with some dependence on the information
content. Finally, a related new experiment was carried out with olive oil and
chilli pepper powder that was dissolved in it while the mass variations were
recorded and a positive mass transient of 0.3 milligram was observed for about
10 minutes. The process represents the writing of new random information into a
medium. The only classical interpretation of this mechanism would be the
compression of trapped air between the grains by the surface tension of the
oil, or that of in pores by capillary forces, and the resulting decrease of the
Archimedes force due volume reduction.


title: Nonlinear structure in a current-carrying collisional dusty plasma

abstract:
  A perpendicular ion drift is investigated as a mechanism for the generation
of magnetic field structures in a highly collisional dusty plasma. The basic
dissipation mechanism is assumed to be the dust-neutrals momentum exchange, so
that plasmas with a small ionization fraction are natural candidates for
experiments. The model reduces to a nonlinear partial differential equation for
the vector potential. The conditions for linear instability are determined. The
stationary states are periodic arrangements for the magnetic field, described
by a Lienard equation. The fully depleted (ion-dust) case is also considered in
detail. Applications to planetary rings, comets and dust acoustic instability
experiments are analyzed. A necessary condition for the validity of the model
is a sufficiently slow time-scale of the generated magnetic fields.


title:
Effects of physics beyond the standard model on the neutrino charge
  radius: an effective Lagrangian approach

abstract:
  In this work, we look for possible new physics effects on the electromagnetic
charge and anapole form factors, $f_Q(q^2)$ and $f_A(q^2)$, for a massless
Dirac neutrino, when these quantities are calculated in the context of an
effective electroweak Yang-Mills theory, which induces the most general
$SU_L(2)$--invariant Lorentz tensor structure of nonrenormalizable type for the
$WW\gamma$ vertex. It is found that in this context, besides the standard model
contribution, the additional contribution to $f_{Q}(q^2)$ and $f_{A}(q^2)$
($f_{Q}^{O_W}(q^2)$ and $f_{A}^{O_W}(q^2)$, respectively) are gauge independent
and finite functions of $q^2$ after adopting a renormalization scheme. These
form factors, $f_{Q}^{O_W}(q^2)$ and $f_{A}^{O_W}(q^2)$, get contribution at
the one loop level only from the proper neutrino electromagnetic vertex.
Besides, the relation $f_{Q}^{eff}(q^2)=q^2f_{A}^{eff}(q^2)$
($f_{Q}^{eff}(q^2)=f_{Q}^{SM}(q^2)+f_{Q}^{O_W}(q^2)$,
$f_{A}^{eff}(q^2)=f_{A}^{SM}(q^2)+f_{A}^{O_W}(q^2)$) is still fulfilled and
hence the relation $a_{\nu}^{eff} = < r^2_{\nu} > ^{eff} /6$ ($a_{\nu}^{eff} =
a_{\nu}^{SM}+ a_{\nu}^{O_W}$, $<r^2_{\nu} > ^{eff} = < r^2_{\nu} > ^{SM}+<
r^2_{\nu} > ^{O_W}$)is gotten, just as in the SM. Using the experimental
constraint on the anomalous $WW\gamma$ vertex, a value for the additional
contribution to the charge radius of $|< r^2_{\nu} >^{O_W}| \lsim 10^{-34}
cm^2$ is obtained, which is one order of magnitude lower than the SM value.


title: Properties of Nucleon Resonances by means of a Genetic Algorithm

abstract:
  We present an optimization scheme that employs a Genetic Algorithm (GA) to
determine the properties of low-lying nucleon excitations within a realistic
photo-pion production model based upon an effective Lagrangian. We show that
with this modern optimization technique it is possible to reliably assess the
parameters of the resonances and the associated error bars as well as to
identify weaknesses in the models. To illustrate the problems the optimization
process may encounter, we provide results obtained for the nucleon resonances
$\Delta$(1230) and $\Delta$(1700). The former can be easily isolated and thus
has been studied in depth, while the latter is not as well known
experimentally.


title:
First order perturbations of the Einstein-Straus and Oppenheimer-Snyder
  models

abstract:
  We derive the linearly perturbed matching conditions between a Schwarzschild
spacetime region with stationary and axially symmetric perturbations and a FLRW
spacetime with arbitrary perturbations. The matching hypersurface is also
perturbed arbitrarily and, in all cases, the perturbations are decomposed into
scalars using the Hodge operator on the sphere. This allows us to write down
the matching conditions in a compact way. In particular, we find that the
existence of a perturbed (rotating, stationary and vacuum) Schwarzschild cavity
in a perturbed FLRW universe forces the cosmological perturbations to satisfy
constraints that link rotational and gravitational wave perturbations. We also
prove that if the perturbation on the FLRW side vanishes identically, then the
vacuole must be perturbatively static and hence Schwarzschild. By the dual
nature of the problem, the first result translates into links between
rotational and gravitational wave perturbations on a perturbed
Oppenheimer-Snyder model, where the perturbed FLRW dust collapses in a
perturbed Schwarzschild environment which rotates in equilibrium. The second
result implies in particular that no region described by FLRW can be a source
of the Kerr metric.


title: Baxter permutations and plane bipolar orientations

abstract:
  We present a simple bijection between Baxter permutations of size $n$ and
plane bipolar orientations with n edges. This bijection translates several
classical parameters of permutations (number of ascents, right-to-left maxima,
left-to-right minima...) into natural parameters of plane bipolar orientations
(number of vertices, degree of the sink, degree of the source...), and has
remarkable symmetry properties. By specializing it to Baxter permutations
avoiding the pattern 2413, we obtain a bijection with non-separable planar
maps. A further specialization yields a bijection between permutations avoiding
2413 and 3142 and series-parallel maps.


title: A degree bound for globally generated vector bundles

abstract:
  We obtain a sharp bound on the degree of a globally generated vector bundle
over a reduced irreducible projective variety defined over an algebraically
closed field of characteristic zero. As an application, we obtain a Del
Pezzo-Bertini type theorem on varieties of minimal degree for subvarieties of
Grassmannians.


title:
A model of a 2d non-Fermi liquid with SO(5) symmetry, AF order, and a
  d-wave SC gap

abstract:
  Demanding a consistent quantum field theory description of spin 1/2 particles
near a circular Fermi surface in 2d leads to a unique fermionic theory with
relevant quartic interactions which has an emergent Lorentz symmetry and
automatically has an Sp(4) = SO(5) internal symmetry. The free theory has
resistivity linear in temperature. The interacting theory has a low-energy
interacting fixed point and is thus a non-Landau/Fermi liquid.
Anti-ferromagnetic (AF) and superconducting (SC) order parameters are bilinears
in the fields and form the 5-dimensional vector representation of SO(5). An AF
phase occurs at low doping which terminates in a first order transition. We
incorporate momentum dependent scattering of Cooper pairs near the Fermi
surface to 1-loop and derive a new kind of SC gap equation beyond mean field
with a d-wave gap solution. Taking into account the renormalization group (RG)
scaling properties near the low energy fixed point, we calculate the complete
phase diagram as a function of doping, which shows some universal geometric
features. The d-wave SC dome terminates on the over-doped side at the fixed
point of the RG,which is a quantum critical point. Optimal doping is estimated
to occur just below 3/2\pi^2. The critical temperature for SC at optimal doping
is set mainly by the universal nodal Fermi velocity and lattice spacing, and is
estimated to average around 140K for LSCO. The pseudogap energy scale is
identified as the RG scale of the coupling.


title: Four manifolds with two-positive Ricci curvature

abstract:
  This paper has been withdrawn by the author, due to an error in the proof of
Theorem 3.8.


title: An Exploratory Search for z~6 Quasars in the UKIDSS Early Data Release

abstract:
  We conducted an exploratory search for quasars at z~ 6 - 8, using the Early
Data Release from United Kingdom Infrared Deep Sky survey (UKIDSS)
cross-matched to panoramic optical imagery. High redshift quasar candidates are
chosen using multi-color selection in i,z,Y,J,H and K bands. After removal of
apparent instrumental artifacts, our candidate list consisted of 34 objects. We
further refined this list with deeper imaging in the optical for ten of our
candidates. Twenty-five candidates were followed up spectroscopically in the
near-infrared and in the optical. We confirmed twenty-five of our spectra as
very low-mass main-sequence stars or brown dwarfs, which were indeed expected
as the main contaminants of this exploratory search. The lack of quasar
detection is not surprising: the estimated probability of finding a single z>6
quasar down to the limit of UKIDSS in the 27.3 square degrees of the EDR is
<5%. We find that the most important limiting factor in this work is the depth
of the available optical data. Experience gained in this pilot project can help
refine high-redshift quasar selection criteria for subsequent UKIDSS data
releases.


title: Free fields in skew fields

abstract:
  Building on the work of K. Chiba (J. Algebra 263 (2003), 75-87), we present
sufficient conditions for the completion of a division ring with respect to the
metric defined by a discrete valuation function to contain a free field, i.e.
the universal field of fractions of a free associative algebra. Several
applications to division rings generated by torsion-free nilpotent groups, skew
Laurent series and related division rings are discussed.


title:
Reconciling Grand Unification with Strings by Anisotropic
  Compactifications

abstract:
  We analyze gauge coupling unification in the context of heterotic strings on
anisotropic orbifolds. This construction is very much analogous to effective 5
dimensional orbifold GUT field theories. Our analysis assumes three fundamental
scales, the string scale, $\mstring$, a compactification scale, $\mc$, and a
mass scale for some of the vector-like exotics, $\mex$; the other exotics are
assumed to get mass at $\mstring$. In the particular models analyzed, we show
that gauge coupling unification is not possible with $\mex = \mc$ and in fact
we require $\mex \ll \mc \sim 3 \times 10^{16}$ GeV. We find that about 10% of
the parameter space has a proton lifetime (from dimension 6 gauge exchange)
$10^{33} {\rm yr} \lesssim\tau(p\to \pi^0e^+) \lesssim 10^{36} {\rm yr}$. The
other 80% of the parameter space gives proton lifetimes below Super-K bounds.
The next generation of proton decay experiments should be sensitive to the
remaining parameter space.


title:
Transverse conformal Killing forms and a Gallot-Meyer Theorem for
  foliations

abstract:
  We study transverse conformal Killing forms on foliations and prove a
Gallot-Meyer theorem for foliations. Moreover, we show that on a foliation with
$C$-positive normal curvature, if there is a closed basic 1-form $\phi$ such
that $\Delta_B\phi=qC\phi$, then the foliation is transversally isometric to
the quotient of a $q$-sphere.


title:
A chiral lagrangian with Broken Scale: testing the restoration of
  symmetries in astrophysics and in the laboratory

abstract:
  We study matter at high density and temperature using a chiral lagrangian in
which the breaking of scale invariance is regulated by the value of a scalar
field, called dilaton
\cite{Heide:1993yz,Carter:1995zi,Carter:1996rf,Carter:1997fn}. We provide a
phase diagram describing the restoration of chiral and scale symmetries. We
show that chiral symmetry is restored at large temperatures, but at low
temperatures it remains broken at all densities. We also show that scale
invariance is more easily restored at low rather than large baryon densities.
The masses of vector mesons scale with the value of the dilaton and their
values initially slightly decrease with the density but then they increase
again for densities larger than $\sim 3 \rho_0$. The pion mass increases
continuously with the density and at $\rho_0$ and T=0 its value is $\sim$ 30
MeV larger than in the vacuum. We show that the model is compatible with the
bounds stemming from astrophysics, as e.g. the one associated with the maximum
mass of a neutron star. The most striking feature of the model is a very
significant softening at large densities, which manifests also as a strong
reduction of the adiabatic index. While the softening has probably no
consequence for Supernova explosion via the direct mechanism, it could modify
the signal in gravitational waves associated with the merging of two neutron
stars.


title: Influence of confinement on granular penetration by impact

abstract:
  We study experimentally the influence of confinement on the penetration depth
of impacting spheres into a granular medium contained in a finite cylindrical
vessel. The presence of close lateral walls reduces the penetration depth, and
the characteristic distance for these lateral wall effects is found to be of
the order of one sphere diameter. The influence of the bottom wall is found to
have a much shorter range.


title: MHV amplitudes in N=2 SQCD and in N=4 SYM at one loop

abstract:
  Using four-dimensional unitarity and MHV-rules we calculate the one-loop MHV
amplitudes with all external particles in the adjoint representation for N=2
supersymmetric QCD with N_f fundamental flavours. We start by considering such
amplitudes in the superconformal N=4 gauge theory where the N=4 supersymmetric
Ward identities (SWI) guarantee that all MHV amplitudes for all types of
external particles are given by the corresponding tree-level result times a
universal helicity- and particle-type-independent contribution. In N=2 SQCD the
MHV amplitudes differ from those for N=4 for general values of N_f and N_c.
However, for N_f=2N_c where the N=2 SQCD is conformal, the N=2 MHV amplitudes
(with all external particles in the adjoint representation) are identical to
the N=4results. This factorisation at one-loop motivates us to pose a question
if there may be a BDS-like factorisation for these amplitudes which also holds
at higher orders of perturbation theory in superconformal N=2 theory.


title:
MHV amplitudes, Wilson loops and the BDS ansatz in the superconformal
  N=2 QCD

abstract:
  This paper has been withdrawn by the author due to an error made in the
analysis of MHV amplitudes with external fundamental matter fields in the
superconformal N=2 SQCD.


title: Binary-black-hole initial data with nearly-extremal spins

abstract:
  There is a significant possibility that astrophysical black holes with
nearly-extremal spins exist. Numerical simulations of such systems require
suitable initial data. In this paper, we examine three methods of constructing
binary-black-hole initial data, focusing on their ability to generate black
holes with nearly-extremal spins: (i) Bowen-York initial data, including
standard puncture data (based on conformal flatness and Bowen-York extrinsic
curvature), (ii) standard quasi-equilibrium initial data (based on the
extended-conformal-thin-sandwich equations, conformal flatness, and maximal
slicing), and (iii) quasi-equilibrium data based on the superposition of
Kerr-Schild metrics. We find that the two conformally-flat methods (i) and (ii)
perform similarly, with spins up to about 0.99 obtainable at the initial time.
However, in an evolution, we expect the spin to quickly relax to a
significantly smaller value around 0.93 as the initial geometry relaxes. For
quasi-equilibrium superposed Kerr-Schild (SKS) data [method (iii)], we
construct initial data with \emph{initial} spins as large as 0.9997. We evolve
SKS data sets with spins of 0.93 and 0.97 and find that the spin drops by only
a few parts in 10^4 during the initial relaxation; therefore, we expect that
SKS initial data will allow evolutions of binary black holes with relaxed spins
above 0.99. [Abstract abbreviated; full abstract also mentions several
secondary results.]


title:
Fermi-surface induced modulation in an optimally doped YBCO
  superconductor

abstract:
  We have observed a Fermi-surface (FS) induced lattice modulation in a YBCO
superconductor with a wavevector along CuO chains, {\it i.e.} ${\bf
q}_1$=(0,$\delta$,0). The value of $\delta\sim0.21$ is twice the Fermi
wavevector ($2{\bf k}_F$) along {\bf b*} connecting nearly nested FS `ridges'.
The ${\bf q}_1$ modulation exists only within O-vacancy-ordered islands
(characterized by ${\bf q}_0$=$(\frac14,0,0))$ and persists well above and
below $T_c$. Our results are consistent with the presence of a FS-induced
charge-density wave.


title: Embedding nonlinear O(6) sigma model into N=4 super-Yang-Mills theory

abstract:
  Anomalous dimensions of high-twist Wilson operators have a nontrivial scaling
behavior in the limit when their Lorentz spin grows exponentially with the
twist. To describe the corresponding scaling function in planar N=4 SYM theory,
we analyze an integral equation recently proposed by Freyhult, Rej and
Staudacher and argue that at strong coupling it can be casted into a form
identical to the thermodynamical Bethe Ansatz equations for the nonlinear O(6)
sigma model. This result is in a perfect agreement with the proposal put
forward by Alday and Maldacena within the dual string description, that the
scaling function should coincide with the energy density of the nonlinear O(6)
sigma model embedded into AdS_5xS^5.


title: Fourier Modeling of the Radio Torus Surrounding Supernova 1987A

abstract:
  We present detailed Fourier modeling of the radio remnant of Supernova 1987A,
using high-resolution 9 GHz and 18 GHz data taken with the Australia Telescope
Compact Array over the period 1992 to 2008. We develop a parameterized
three-dimensional torus model for the expanding radio shell, in which the
emission is confined to an inclined equatorial belt; our model also
incorporates both a correction for light travel-time effects and an overall
east-west gradient in the radio emissivity. By deriving an analytic expression
for the two-dimensional Fourier transform of the projected three-dimensional
brightness distribution, we can fit our spatial model directly to the
interferometric visibility data. This provides robust estimates to the radio
morphology at each epoch. The best-fit results suggest a constant remnant
expansion at 4000 +/- 400 km/s over the 16-year period covered by the
observations. The model fits also indicate substantial mid-latitude emission,
extending to 40 degree on either side of the equatorial plane. This likely
corresponds to the extra-planar structure seen in H$\alpha$ and Ly$\alpha$
emission from the supernova reverse shock, and broadly supports hydrodynamic
models in which the complex circumstellar environment was produced by a
progression of interacting winds from the progenitor. Our model quantifies the
clear asymmetry seen in the radio images: we find that the eastern half of the
radio remnant is consistently ~40 brighter than the western half at all epochs,
which may result from an asymmetry in the ejecta distribution between these two
hemispheres.


title: Statistical Predictions From Anarchic Field Theory Landscapes

abstract:
  Consistent coupling of effective field theories with a quantum theory of
gravity appears to require bounds on the the rank of the gauge group and the
amount of matter. We consider landscapes of field theories subject to such to
boundedness constraints. We argue that appropriately "coarse-grained" aspects
of the randomly chosen field theory in such landscapes, such as the fraction of
gauge groups with ranks in a given range, can be statistically predictable. To
illustrate our point we show how the uniform measures on simple classes of N=1
quiver gauge theories localize in the vicinity of theories with certain typical
structures. Generically, this approach would predict a high energy theory with
very many gauge factors, with the high rank factors largely decoupled from the
low rank factors if we require asymptotic freedom for the latter.


title: Lick Indices in the Thin and Thick Disks of Edge-On Disk Galaxies

abstract:
  We have measured Lick index equivalent widths to derive luminosity weighted
stellar ages and metallicities for thin and thick disk dominated regions of 9
edge-on disk galaxies with the ARC 3.5 meter telescope at Apache Point
Observatory. In all cases, the thick disks are confirmed to be old stellar
populations, with typical ages between 4 and 10 Gyr. The thin disks are
uniformly younger than the thick disks, and show strong radial age gradients,
with the outer regions of the disks being younger than 1 Gyr. We do not detect
any significant metallicity differences or alpha-element enhancement in the
thick disk stars compared to the thin disk, due to the insensitivity of the
Lick indices to these differences at low metallicity. We compare these results
to thick disks measured in other systems and to predictions from thick disk
formation models.


title:
Realizing the strongly correlated $d$-Mott state in a fermionic cold
  atom optical lattice

abstract:
  We show that a new state of matter, the d-wave Mott-insulator state (d-Mott
state) (introduced recently by [H. Yao, W. F. Tsai, and S. A. Kivelson, Phys.
Rev. B 76, 161104 (2007)]), which is characterized by a non-zero expectation
value of a local plaquette operator embedded in an insulating state, can be
engineered using ultra-cold atomic fermions in two-dimensional double-well
optical lattices. We characterize and analyze the parameter regime where the
$d$-Mott state is stable. We predict the testable signatures of the state in
the time-of-flight measurements.