title: Nonadiabatic Dynamics of Atoms in Nonuniform Magnetic Fields

abstract:
  Dynamics of neutral atoms in nonuniform magnetic fields, typical of
quadrupole magnetic traps, is considered by applying an accurate method for
solving nonlinear systems of differential equations. This method is more
general than the adiabatic approximation and, thus, permits to check the limits
of the latter and also to analyze nonadiabatic regimes of motion. An unusual
nonadiabatic regime is found when atoms are confined from one side of the
z-axis but are not confined from another side. The lifetime of atoms in a trap
in this semi-confining regime can be sufficiently long for accomplishing
experiments with a cloud of such atoms. At low temperature, the cloud is
ellipsoidal being stretched in the axial direction and moving along the z-axis.
The possibility of employing the semi-confining regime for studying the
relative motion of one component through another, in a binary mixture of gases
is discussed.


title: Surface Action for a Point Particle

abstract:
  A remark on the movement of a point mass particle is given. If one associates
to the particle a sphere of radius equal to the related De Broglie length, the
relativistic action on the trajectory is proportional to the surface described
by this sphere.


title: Average Number of Coherent Modes for Pulse Random Fields

abstract:
  Some consequences of spatio-temporal symmetry for the deterministic
decomposition of complex light fields into factorized components are
considered. This enables to reveal interrelations between spatial and temporal
coherence properties of wave. An estimation of average number of the
decomposition terms is obtained in the case of statistical ensemble of light
pulses.


title: Excitation and relaxation in atom-cluster collisions

abstract:
  Electronic and vibrational degrees of freedom in atom-cluster collisions are
treated simultaneously and self-consistently by combining time-dependent
density functional theory with classical molecular dynamics. The gradual change
of the excitation mechanisms (electronic and vibrational) as well as the
related relaxation phenomena (phase transitions and fragmentation) are studied
in a common framework as a function of the impact energy (eV...MeV). Cluster
"transparency" characterized by practically undisturbed atom-cluster
penetration is predicted to be an important reaction mechanism within a
particular window of impact energies.


title: Landau damping: is it real?

abstract:
  To calculate linear oscillations and waves in dynamics of gas and plasma one
uses as a rule the old classical method of dispersion equation for complex
frequencies $\omega$ and wave numbers $k$: $\epsilon(\omega,k)=0$. This method
appears to be inapplicable, f.e., in the case of waves in Maxwellian
collisionless plasma when dispersion equation has no solutions. By means of
some refined sophistication L.~Landau in 1946 has suggested in this case
actually to replace the dispersion equation with another one, having a specific
solution (``Landau damping'') and being now widely used in plasma physics.
Recently we have suggested a quite new universal method of two-dimensional
Laplace transformation (in coordinate $x$ and time $t$ for plane wave case),
that allows to obtain asymptotical solutions of original Vlasov plasma
equations as inseparable sets of coupled oscillatory modes (but not a single
wave like $\exp(-i\omega t+i k x)$). The mode parameters are defined in this
case by double-poles ($\omega_n$,$k_n$) of Laplace image $E(\omega_n,k_n)$ of
electrical field $E(x,t)$. This method allows one to obtain the whole set of
oscillatory modes for every concrete problem. It leads to some new ideology in
the theory of plasma oscillations, which are considered as a combination of
coupled oscillatory modes (characterized by pairs ($\omega_n$,$k_n$) and
amplitudes) and depend not only on the intrinsic plasma parameters, but also on
mutually dependent self-consistent initial and boundary conditions and on
method of plasma oscillations excitation.


title: Hamiltonian Structure for Classical Electrodynamics of a Point Particle

abstract:
  We prove that, contrary to the common belief, the classical Maxwell
electrodynamics of a point-like particle may be formulated as an
infinite-dimensional Hamiltonian system. We derive well defined
quasi-Hamiltonian which possesses direct physical interpretation being equal to
the total energy of the composed (field + particle) system. The phase space of
this system is endowed with an interesting symplectic structure. We prove that
this structure is strongly non-degenerated and, therefore, enables one to
define consistent Poisson bracket for particle's and field degrees of freedom.
We stress that this formulation is perfectly gauge-invariant.


title:
On the absence of dissipative instability of negative energy waves in
  hydrodynamic shear flows

abstract:
  Stability criterion for the surface gravity capillary waves in a flowing
two-layered fluid system with viscous dissipation is investigated. It is seen
that the dissipative instability of negative energy waves is absent,- contrary
to what earlier authors have concluded. Their error is identified to arise from
an erroneous choice of the dissipation law, in which the wave profile velocity
is wrongly equated to the particle velocity. Our corrected dissipation law is
also shown to restore Galilean invariance to the stability condition of the
system.


title: Hamilton-Jacobi approach to Berezinian singular systems

abstract:
  In this work we present a formal generalization of the Hamilton-Jacobi
formalism, recently developed for singular systems, to include the case of
Lagrangians containing variables which are elements of Berezin algebra. We
derive the Hamilton-Jacobi equation for such systems, analizing the singular
case in order to obtain the equations of motion as total differential equations
and study the integrability conditions for such equations. An example is solved
using both Hamilton-Jacobi and Dirac's Hamiltonian formalisms and the results
are compared.


title: Analysis of Molecular Rotational Spectra

abstract:
  Rotational spectra of diatomic molecules measured in the high-precision
experiments are analyzed. Such a spectrum is usually fitted by an 8th order
polynomial in spin. In fact, from the theoretical point of view, the rotational
spectrum is expected to be a smooth function of spin. Thus, fitting the
rotational spectrum in terms of a low order polynomial in spin seems to be
justified. However, this is not what we found in the present work. We show that
the measured spectrum is not necessarily a smooth function of the spin, which
is quite surprising. Whether or not it indicates the presence of some hidden
physics is an open question.


title: Relativistic flows on a spacetime lattice

abstract:
  The relativistic extension of non-relativistic hydrodynamics suffers from
notorious difficulties. In non-relativistic hydrodynamics where difficulties
also abound, it has proved a useful supplement to study lattice models which
can imitate viscous fluid flow. In this paper we construct a relativistic
spacetime lattice and construct a dynamics of points, thus a relativistic
cellular automaton over it, to model relativistic fluid flow. A simple example
is also explicitly studied, and some numerical results with figures are shown
in the last section.


title: Symmetries of particle motion

abstract:
  We define affine transport lifts on the tangent bundle by associating a
transport rule for tangent vectors with a vector field on the base manifold.
The aim is to develop tools for the study of kinetic/ dynamical symmetries in
relativistic particle motion. The transport lift unifies and generalises the
various existing lifted vector fields, with clear geometric interpretations. We
find the affine dynamical symmetries of free particle motion, and compare this
to previous results and to the alternative concept of "matter symmetry".


title: Shape Changes of Self-Assembled Actin Bilayer Composite Membranes

abstract:
  We report the self-assembly of thin actin shells beneath the membranes of
giant vesicles. Ion-carrier mediated influx of Mg2+ induces actin
polymerization in the initially spherical vesicles. Buckling of the vesicles
and the formation of blisters after thermally induced bilayer expansion is
demonstrated. Bilayer flickering is dominated by tension generated by its
coupling to the actin cortex. Quantitative flicker analysis suggests the
bilayer and the actin cortex are separated by 0.4 \mum to 0.5 \mum due to
undulation forces.


title:
Signature of metastable electrons in highly charged ion surface
  interactions

abstract:
  We present autoionization spectra of metastable Ar(8+) and C(4+), N(5+),
O(6+) and Ne(8+) scattering off an Al(111) surface with incident energies down
to 5 eV. The unprecedented quality of the experimental data permits the
observation of a unique, yet undiscovered peak in the structures originating
from the metastable projectiles compared to corresponding ground state
configurations. Analyzing the peak positions for different projectile species
and velocities we demonstrate that the peak must be ascribed to an
above-surface transition under participation of the metastable state.


title: Non-commutative time-frequency tomography

abstract:
  The characterization of non-stationary signals requires joint time and
frequency information. However, time (t) and frequency (omega) being
non-commuting variables there cannot be a joint probability density in the
(t,omega) plane and the time-frequency distributions, that have been proposed,
have difficult interpretation problems arising from negative or complex values
and spurious components. As an alternative we propose to obtain time-frequency
information by looking at the marginal distributions along rotated directions
in the (t,omega) plane. The rigorous probability interpretation of the marginal
distributions avoids all interpretation ambiguities. Applications to signal
analysis and signal detection are discussed as well as an extension of the
method to other pairs of non-commuting variables.


title: Linac-Ring Type Colliders: Fourth Way To TeV Scale

abstract:
  The present status of suggested linac-ring type ep and gamma-p colliders is
reviewed. The main parameters of these machines as well as e-nucleus and
gamma-nucleus colliders are considered. It is shown that sufficiently high
luminosities may be achieved with a reasonable improvement of proton and
electron beam parameters.


title: A mathematical model for Neanderthal extinction

abstract:
  A simple mathematical homogeneous model of competition is used to describe
Neanderthal extinction in Europe. It considers two interacting species,
Neanderthals and Early Modern Men, in the same ecological niche. Using
paleontological data we claim that the parameter of similarity, between both
species, fluctuates between 0.992 and 0.997. An extension of the model
including migration (diffusion) is also discussed nevertheless, extinction of
Neanderthal seems unavoidable. Numerical analysis of travelling wave solution
(fronts) comfirms the extinction. The wave-front-velocity is estimated from
linear analysis and numerical simulations confirm this estimation. We
conjecture a mathematical formulation for the principle of exclusion between
competitive interacting species (Gause).


title: Do Topological Charge Solitons Participate in DNA Activity?

abstract:
  We present a novel electromagnetic model of DNA molecules, in which the
P-bonds act as tunnel junctions and the H-bonds as capacitors. Excess charge in
the model gives rise to two coupled modified sine-Gordon equations, which admit
topological solitonic excitations. We study the dynamics of the solitons, their
effect on the DNA transport properties, and comment about their role in the DNA
functioning. We propose specific experiments in order to test our predictions.


title: Continuous Iteration of Dynamical Maps

abstract:
  A precise meaning is given to the notion of continuous iteration of a
mapping. Usual discrete iterations are extended into a dynamical flow which is
a homotopy of them all. The continuous iterate reveals that a dynamical map is
formend by independent component modes envolving without interference with each
other.


title: Anyons, Monopole and Coulomb Problem

abstract:
  The monopole systems with hidden symmetry of the two-dimensional Coulomb
problem are considered.
  One of them, the "charge-charged magnetic vortex" with a half-spin, is
constructed by reducing the quantum circular oscillator with respect to the
action of the parity operator.
  The other two systems are constructed by reduction from the two-dimensional
complex space. The first system is a particle on the sphere in the presence of
the exterior constant magnetic field (generated by Dirac's monopole located in
its center). This system is dual to the massless (3+1)-dimensional particle
with fixed energy. The second system represents the particle on the
pseudosphere in the presence of exterior magnetic field and is dual to the
massive relativistic anyon.


title:
Positronium in crossed electric and magnetic fields: the existence of a
  long-lived ground state

abstract:
  It was earlier reported [PRL 78 199, (1997)] that long-lived excited states
of positronium can be formed in crossed electric and magnetic fields at
laboratory field strengths. Unlike the lower-lying states that are localized in
the magnetically distorted Coulomb well, these long-lived states which can
possess a lifetime up to many years are localized in an outer potential well
that is formed for certain values of the pseudomomentum and magnetic field. The
present work extends the original analysis and studies the dependence of the
spectrum as a function of field strength and pseudomomentum over a wide range
of parameters. We predict that in the limit of large pseudomomentum, the ground
state of positronium atom in a magnetic field will become delocalized; for
strong fields, the binding energy of this state is quite large, resulting in a
ground state that is both stable against direct annihilation and against
ionization by low frequency background radiation.


title: Space-Time Approach to Scattering from Many Body Systems

abstract:
  We present scattering from many body systems in a new light. In place of the
usual van Hove treatment, (applicable to a wide range of scattering processes
using both photons and massive particles) based on plane waves, we calculate
the scattering amplitude as a space-time integral over the scattering sample
for an incident wave characterized by its correlation function which results
from the shaping of the wave field by the apparatus. Instrument resolution
effects - seen as due to the loss of correlation caused by the path differences
in the different arms of the instrument are automatically included and analytic
forms of the resolution function for different instruments are obtained. The
intersection of the moving correlation volumes (those regions where the
correlation functions are significant) associated with the different elements
of the apparatus determines the maximum correlation lengths (times) that can be
observed in a sample, and hence, the momentum (energy) resolution of the
measurement. This geometrical picture of moving correlation volumes derived by
our technique shows how the interaction of the scatterer with the wave field
shaped by the apparatus proceeds in space and time. Matching of the correlation
volumes so as to maximize the intersection region yields a transparent,
graphical method of instrument design. PACS: 03.65.Nk, 3.80 +r, 03.75, 61.12.B


title: Electron detachment from negative ions in bichromatic laser field

abstract:
  Negative ion detachment in two-colour laser field is considered within the
recent modification of Keldysh model which makes it quantitatively reliable.
The general approach is illustrated by calculation of angular differential
detachment rates, partial rates for particular ATD (Above Threshold Detachment)
channels and total detachment rates for H$^-$ ion in bichromatic field with 1:2
frequency ratio. Both perturbative and strong field regimes are examined. Polar
asymmetry and phase effects are quantitatively characterized with some new
features revealed. Phase effects are found to result in a huge anisotropy
factor $\sim 10^3$ in the electron angular distribution in the perturbative
regime.


title:
A two-dimensional, two-electron model atom in a laser pulse: exact
  treatment, single active electron-analysis, time-dependent density functional
  theory, classical calculations, and non-sequential ionization

abstract:
  Owing to its numerical simplicity, a two-dimensional two-electron model atom,
with each electron moving in one direction, is an ideal system to study
non-perturbatively a fully correlated atom exposed to a laser field. Frequently
made assumptions, such as the ``single active electron''- approach and
calculational approximations, e.g. time dependent density functional theory or
(semi-) classical techniques, can be tested. In this paper we examine the
multiphoton short pulse-regime. We observe ``non-sequential'' ionization, i.e.\
double ionization at lower field strengths as expected from a sequential,
single active electron-point of view. Since we find non-sequential ionization
also in purely classical simulations, we are able to clarify the mechanism
behind this effect in terms of single particle trajectories. PACS Number(s):
32.80.Rm


title:
A New Young Diagrammatic Method For Kronecker Products of O(n) and
  Sp(2m)

abstract:
  A new simple Young diagrammatic method for Kronecker products of O(n) and
Sp(2m) is proposed based on representation theory of Brauer algebras. A general
procedure for the decomposition of tensor products of representations for O(n)
and Sp(2m) is outlined, which is similar to that for U(n) known as the
Littlewood rules together with trace contractions from a Brauer algebra and
some modification rules given by King.


title: Closed Expressions for Lie Algebra Invariants and Finite Transformations

abstract:
  A simple procedure to obtain complete, closed expressions for Lie algebra
invariants is presented. The invariants are ultimately polynomials in the group
parameters. The construction of finite group elements require the use of
projectors, whose coefficients are invariant polynomials. The detailed general
forms of these projectors are given. Closed expressions for finite Lorentz
transformations, both homogeneous and inhomogeneous, as well as for Galilei
transformations, are found as examples.


title: An Alternative Basis for the Wigner-Racah Algebra of the Group SU(2)

abstract:
  The Lie algebra of the classical group SU(2) is constructed from two quon
algebras for which the deformation parameter is a common root of unity. This
construction leads to (i) a not very well-known polar decomposition of the
ladder generators of the SU(2) Lie algebra and to (ii) an alternative to the
(J,M) quantization scheme, viz., the (J,alpha) quantization scheme. The key
ideas for developing the Wigner-Racah algebra of the group SU(2) in the
(J,alpha) scheme are given. In particular, some properties of the coupling and
recoupling coefficients as well as the Wigner-Eckart theorem in the (J,alpha)
scheme are briefly discussed.

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


title: Characteristic functions and process identification by neural networks

abstract:
  Principal component analysis (PCA) algorithms use neural networks to extract
the eigenvectors of the correlation matrix from the data. However, if the
process is non-Gaussian, PCA algorithms or their higher order generalisations
provide only incomplete or misleading information on the statistical properties
of the data. To handle such situations we propose neural network algorithms,
with an hybrid (supervised and unsupervised) learning scheme, which constructs
the characteristic function of the probability distribution and the transition
functions of the stochastic process. Illustrative examples are presented, which
include Cauchy and Levy-type processes


title: Properties of resonant activation phenomena

abstract:
  The phenomenon of resonant activation of a Brownian particle over a
fluctuating barrier is revisited. We discuss the important distinctions between
barriers that can fluctuate among "up" and "down" configurations, and barriers
that are always "up" but that can fluctuate among different heights. A
resonance as a function of the barrier fluctuation rate is found in both cases,
but the nature and physical description of these resonances is quite distinct.
The nature of the resonances, the physical basis for the resonant behavior, and
the importance of boundary conditions are discussed in some detail. We obtain
analytic expressions for the escape time over the barrier that explicitly
capture the minima as a function of the barrier fluctuation rate, and show that
our analytic results are in excellent agreement with numerical results.

categories: physics.chem-ph math-ph math.MP physics.class-ph


title: Logarithmic perturbation theory for quasinormal modes

abstract:
  Logarithmic perturbation theory (LPT) is developed and applied to quasinormal
modes (QNMs) in open systems. QNMs often do not form a complete set, so LPT is
especially convenient because summation over a complete set of unperturbed
states is not required. Attention is paid to potentials with exponential tails,
and the example of a Poschl-Teller potential is briefly discussed. A numerical
method is developed that handles the exponentially large wavefunctions which
appear in dealing with QNMs.


title: LHC-B Ring Imaging Cherenkov Detector

abstract:
  The progress towards the realisation of the LHC-B Ring Imaging Cherenkov
detector is reported.


title:
Extreme Energy Cosmic Rays (EECR) Observation Capabilities of an
  "Airwatch from Space'' Mission

abstract:
  The longitudinal development and other characteristics of the EECR induced
atmospheric showers can be studied from space by detecting the fluorescence
light induced in the atmospheric nitrogen. According to the Airwatch concept a
single fast detector can be used for measuring both intensity and time
development of the streak of fluorescence light produced by the atmospheric
shower induced by an EECR. In the present communication the detection
capabilities for the EECR observation from space are discussed.


title:
Vibrational Frequencies of the 2p^2A^"_2 and 3d^2E^" States of the
  Triatomic Deuterium Molecule

abstract:
  We investigated the vibrational energies in the 2p^2A^"_2 and 3d^2E^" states
of the triatomic deuterium molecule D_3. The experiments were performed using a
fast neutral beam photoionization spectrometer recently developed at Freiburg.
A depletion type optical double-resonance scheme using two pulsed dye lasers
was applied. The measured vibrational frequencies of the 2p^2A^"_2 state of D_3
are compared to those of H_3 and to theoretical values calculated from an ab
initio potential energy surface. The data give insight into the importance of
the coupling between the valence electron and the ion core.


title: Cross Validated Non parametric Bayesianism by Markov Chain Monte Carlo

abstract:
  Completely automatic and adaptive non-parametric inference is a pie in the
sky. The frequentist approach, best exemplified by the kernel estimators, has
excellent asymptotic characteristics but it is very sensitive to the choice of
smoothness parameters. On the other hand the Bayesian approach, best
exemplified by the mixture of gaussians models, is optimal given the observed
data but it is very sensitive to the choice of prior. In 1984 the author
proposed to use the Cross-Validated gaussian kernel as the likelihood for the
smoothness scale parameter h, and obtained a closed formula for the posterior
mean of h based on Jeffreys's rule as the prior. The practical operational
characteristics of this bayes' rule for the smoothness parameter remained
unknown for all these years due to the combinatorial complexity of the formula.
It is shown in this paper that a version of the metropolis algorithm can be
used to approximate the value of h producing remarkably good completely
automatic and adaptive kernel estimators. A close study of the form of the
cross validated likelihood suggests a modification and a new approach to
Bayesian Non-parametrics in general.


title: Topological Combinatorics of a Quantized String Gravitational Metric

abstract:
  A string-theoretic structure of the standard model is defined having a 4-D
quantum gravity metric consistent with topological and algebraic first
principles. Unique topological diagrams of string states, strong and weak
interactions and quark families are evolved from this metric (but published
separately). The theoretical structure includes known static and dynamic
symmetries. A philosophical perspective on modern physics originates numerous
opportunities for formal mathematical discussion.


title:
Maximum likelihood estimation of photon number distribution from
  homodyne statistics

abstract:
  We present a method for reconstructing the photon number distribution from
the homodyne statistics based on maximization of the likelihood function
derived from the exact statistical description of a homodyne experiment. This
method incorporates in a natural way the physical constraints on the
reconstructed quantities, and the compensation for the nonunit detection
efficiency.


title: Determination of the Fine Structure Constant by $\pi$

abstract:
  In the present report the author presents a simple and systematically defined
formula for the fine structure constant based only on the number $\pi$. The
difference between the suggested value and the currently known experimental one
is about 60 times smaller than the uncertainty interval.


title: Smooth coalgebras

abstract:
  A complete mathematical framework for coalgebraic formulation of
supergeometry and its infinite-dimensional extension is proposed. Within this
approach a supermanifold is defined as a graded coalgebra endowed with a smooth
structure. The category of such coalgebras is constructed and analysed. It is
shown that it contains as its full subcategories both the category of smooth
Fr\'{e}chet manifolds and the category of finite-dimensional
Berezin-Leites-Kostant supermanifolds.


title:
Quantum Algebra of the Particle Moving on the q-Deformed
  Mass-Hyperboloid

abstract:
  I introduce a reality structure on the Heisenberg double of Fun_q(SL(N,C))
for q phase, which for N=2 can be interpreted as the quantum phase space of the
particle on the q-deformed mass-hyperboloid. This construction is closely
related to the q-deformation of the symmetric top. Finally, I conjecture that
the above real form describes zero modes of certain non-compact WZNZ-models.


title:
Physics Opportunities Above the Greisen-Zatsepin-Kuzmin Cutoff: Lorentz
  Symmetry Violation at the Planck Scale

abstract:
  Special relativity has been tested at low energy with great accuracy, but
these results cannot be extrapolated to very high-energy phenomena: this new
domain of physics may actually provide the key to the, yet unsettled, question
of the ether and the absolute rest frame. Introducing a critical distance
scale, a, below 10E-25 cm (the wavelength scale of the highest-energy observed
cosmic rays) allows to consider models, compatible with standard tests of
special relativity, where a small violation of Lorentz symmetry (a can, for
instance, be the Planck length) leads to a deformed relativistic kinematics
(DRK) producing dramatic effects on the properties of very high-energy cosmic
rays. For instance, the Greisen-Zatsepin-Kuzmin (GZK) cutoff does no longer
apply and particles which are unstable at low energy (neutron, some hadronic
resonances like the Delta++, possibly several nuclei...) become stable at very
high energy. In these models, an absolute local rest frame exists (the vacuum
rest frame, VRF) and special relativity is a low-momentum limit. We discuss the
possible effects of Lorentz symmetry violation (LSV) on kinematics and
dynamics, as well as the cosmic-ray energy range (well below the energy scale
associated to the fundamental length) and experiments (on earth and from space)
where they could be detected.


title: Functional determinants via Wronski construction of Green functions

abstract:
  A general technique is developed for calculating functional determinants of
second-order differential operators with Dirichlet, periodic, and antiperiodic
boundary conditions. As an example, we give simple formulas for a harmonic
oscillator with an arbitrary time-dependent frequency. Here our result is a
generalization of Gel'fand-Yaglom's famous formula which was restricted to
Dirichlet boundary conditions. Apart from the generalization, our derivation is
more transparent than theirs, the determinants requiring only knowledge of the
classical trajectories. Special properties of operators with a zero mode are
exhibited. Our technique does not require the calculation of the spectrum and
is as simple as Wronski's method for Green functions.


title: Observing Air Showers from Cosmic Superluminal Particles

abstract:
  The Poincar\'e relativity principle has been tested at low energy with great
accuracy, but its extrapolation to very high-energy phenomena is much less well
established. Lorentz symmetry can be broken at Planck scale due to the
renormalization of gravity or to some deeper structure of matter: we expect
such a breaking to be a very high energy and very short distance phenomenon. If
textbook special relativity is only an approximate property of the equations
describing a sector of matter above some critical distance scale, an absolute
local frame (the "vacuum rest frame", VRF) can possibly be found and
superluminal sectors of matter may exist related to new degrees of freedom not
yet discovered experimentally. The new superluminal particles ("superbradyons",
i.e. bradyons with superluminal critical speed) would have positive mass and
energy, and behave kinematically like "ordinary" particles (those with critical
speed in vacuum equal to c, the speed of light) apart from the difference in
critical speed (c_i >> c where c_i is the critical speed of a superluminal
sector). They may be the ultimate building blocks of matter At speed v > c,
they are expected to release "Cherenkov" radiation ("ordinary" particles) in
vacuum. Superluminal particles could provide most of the cosmic (dark) matter
and produce very high-energy cosmic rays. We discuss: a) the possible relevance
of superluminal matter to the composition, sources and spectra of high-energy
cosmic rays; b) signatures and experiments allowing to possibly explore such
effects. Very large volume and unprecedented background rejection ability are
crucial requirements for any detector devoted to the search for cosmic
superbradyons. Future cosmic-ray experiments using air-shower detectors
(especially from space) naturally fulfil both requirements.


title: Odd Viscosity

abstract:
  When time reversal is broken the viscosity tensor can have a non vanishing
odd part. In two dimensions, and only then, such odd viscosity is compatible
with isotropy. Elementary and basic features of odd viscosity are examined by
considering solutions of the wave and Navier-Stokes equations for hypothetical
fluids where the stress is dominated by odd viscosity.


title: On Localized "X-shaped" Superluminal Solutions to Maxwell Equations

abstract:
  In this paper we extend for the case of Maxwell equations the "X-shaped"
solutions previously found in the case of scalar (e.g., acoustic) wave
equations. Such solutions are localized in theory, i.e., diffraction-free and
particle-like (wavelets), in that they maintain their shape as they propagate.
In the electromagnetic case they are particularly interesting, since they are
expected to be Superluminal. We address also the problem of their practical,
approximate production by finite (dynamic) radiators. Finally, we discuss the
appearance of the X-shaped solutions from the purely geometric point of view of
the Special Relativity theory.
  [PACS nos.: 03.50.De; 1.20.Jb; 03.30.+p; 03.40.Kf; 14.80.-j.
  Keywords: X-shaped waves; localized solutions to Maxwell equations;
Superluminal waves; Bessel beams; Limited-dispersion beams; electromagnetic
wavelets; Special Relativity; Extended Relativity].


title:
Double Complexes and Cohomological Hierarchy in a Space of Weakly
  Invariant Lagrangians of Mechanics

abstract:
  For a given configuration space $M$ and Lie algebra $g$ whose action is
defined on $M$, the space $V_{0.0}$ of weakly $g$-invariant Lagrangians (i.e.
Lagrangians whose motion equations left hand sides are $g$-invariant) is
studied.
  The problem is reformulated in the terms of the double complex of Lie algebra
cochains with values in the complex of Lagrangians. Calculating the cohomology
of this complex using the method of spectral sequences, we come to the
hierarchy in the space $V_{0.0}$:
  The double filtration $V_{s.r}$ ($s=0,1,2,3,4;r=0,1$) and the homomorphisms
on every space $V_{s.r}$ are constructed.
  These homomorphisms take values in cohomologies of the Lie algebra $g$ and
configuration space $M$. On one hand every space $V_{s.r}$ is the kernel of the
corresponding homomorphism, on the other hand this space is defined by its
physical properties.


title: Importance of an Astrophysical Perspective for Textbook Relativity

abstract:
  The importance of a teaching a clear definition of the ``observer'' in
special relativity is highlighted using a simple astrophysical example from the
exciting current research area of ``Gamma-Ray Burst'' astrophysics. The example
shows that a source moving relativistically toward a single observer at rest
exhibits a time ``contraction'' rather than a ``dilation'' because the light
travel time between the source and observer decreases with time. Astrophysical
applications of special relativity complement idealized examples with real
applications and very effectively exemplify the role of a finite light travel
time.


title: On degree zero semistable bundles over an elliptic curve

abstract:
  Motivated by the study of heterotic string compactifications on elliptically
fibered Calabi-Yau manifolds, we present a procedure for testing semistability
and identifying the decomposition type of degree zero holomorphic vector
bundles over a nonsingular elliptic curve. The algorithm requires explicit
knowledge of a basis of sections of an associated `twisted bundle'.


title:
Radiation of Relativistic Charged Particles in a System With One
  Dimensional Randomness

abstract:
  Radiation of relativistic charged particles in a system of randomly spaced
plates is considered in the paper. It is shown that for large number of plates
($N \gg 1$), in the wavelength range $\lambda \ll l\ll L$ (where $l$ is the
photon mean free path and $L$ is the system characteristic size) and for angles
$|\cos \theta |\gg (\lambda/2\pi l)^{1/3}$, pseudophoton diffusion represents
the major mechanism of radiation. Total intensity of radiation is investigated
and its strong dependence on the particle energy and plate number is obtained.


title:
Lorentz symmetry violation at Planck scale, cosmology and superluminal
  particles

abstract:
  Although Lorentz symmetry has been tested at low energy with extremely good
accuracy, its validity at very high energy is much less well established. If
Lorentz symmetry violation (LSV) is energy-dependent (e.g. $\propto E^2$), it
can be of order 1 at Planck scale and undetectable at GeV scale or below.
Similarly, superluminal particles with positive mass and energy (superbradyons)
can exist and be the ultimate building blocks of matter. We discuss a few
cosmological consequences of such a scenario, as well as possible experimental
tests.


title: q-deforming the synchrotron shape function

abstract:
  We replace the usual integral in the shape function of the synchrotron
spectrum by a Jackson (q-deformed) integral and write down the formulas
required to calculate the Jackson first deformed form of the synchrotron shape
function


title: Nonradiative Electronic Deexcitation Time Scales in Metal Clusters

abstract:
  The life-times due to Auger-electron emission for a hole on a deep electronic
shell of neutral and charged sodium clusters are studied for different sizes.
We consider spherical clusters and calculate the Auger-transition probabilities
using the energy levels and wave functions calculated in the
Local-Density-Approximation (LDA).
  We obtain that Auger emission processes are energetically not allowed for
neutral and positively charged sodium clusters. In general, the Auger
probabilities in small Na$_N^-$ clusters are remarkably different from the
atomic ones and exhibit a rich size dependence.
  The Auger decay times of most of the cluster sizes studied are orders of
magnitude larger than in atoms and might be comparable with typical
fragmentation times.


title: Tests of a fiber detector concept for high rate particle tracking

abstract:
  A fiber detector concept is suggested allowing to registrate particles within
less than 100 nsec with a space point precision of about 0.1 mm at low
occuppancy. The fibers should be radiation hard for 1 Mrad/year. Corresponding
prototypes have been build and tested at a 3 GeV electron beam at DESY.
Preliminary results of these tests indicate that the design goal for the
detector is reached.


title: Fiber technology applications for a future e+e- linear collider detector

abstract:
  The advantages and possibilities of fiber technology for the detection of
particles in 500 GeV e+e- reactions are considered. It is suggested to build a
fast trigger which could be used also for intermediate tracking. A fiber
preshower in front of the electromagnetic calorimeter would allow to identify
electrons and photons with a space precision better than 0.1 mm.


title:
An effective method to read out large scintillator areas with precise
  timing

abstract:
  Using scintillator tile technology several square meters of plastic
scintillator are read out by only two photomultiplier with a time precision of
about 1.5 nsec.
  Two examples are discussed to build a detector based on this technology to
search for cosmic muons and neutrinos.


title: The high-intensity hyperon beam at CERN

abstract:
  A high-intensity hyperon beam was constructed at CERN to deliver Sigma- to
experiment WA89 at the Omega facility and operated from 1989 to 1994. The setup
allowed rapid changeover between hyperon and conventional hadron beam
configurations. The beam provided a Sigma-flux of 1.4 x 10^5 per burst at mean
momenta between 330 and 345 Gev/c, produced by about 3 x 10^10 protons of 450
GeV/c . At the experiment target the beam had a Sigma-/pi- ratio close to 0.4
and a size of 1.6 x 3.7 cm^2. The beam particle trajectories and their momenta
were measured with a scintillating fibre hodoscope in the beam channel and a
silicon microstrip detector at the exit of the channel. A fast transition
radiation detector was used to identify the pion component of the beam.


title: Quasi-exactly solvable quartic potential

abstract:
  A new two-parameter family of quasi-exactly solvable quartic polynomial
potentials $V(x)=-x^4+2iax^3+(a^2-2b)x^2+2i(ab-J)x$ is introduced. Until now,
it was believed that the lowest-degree one-dimensional quasi-exactly solvable
polynomial potential is sextic. This belief is based on the assumption that the
Hamiltonian must be Hermitian. However, it has recently been discovered that
there are huge classes of non-Hermitian, ${\cal PT}$-symmetric Hamiltonians
whose spectra are real, discrete, and bounded below [physics/9712001].
Replacing Hermiticity by the weaker condition of ${\cal PT}$ symmetry allows
for new kinds of quasi-exactly solvable theories. The spectra of this family of
quartic potentials discussed here are also real, discrete, and bounded below,
and the quasi-exact portion of the spectra consists of the lowest $J$
eigenvalues. These eigenvalues are the roots of a $J$th-degree polynomial.

categories: math-ph cond-mat hep-th math.MP nlin.SI quant-ph


title: Central extensions of the families of quasi-unitary Lie algebras

abstract:
  The most general possible central extensions of two whole families of Lie
algebras, which can be obtained by contracting the special pseudo-unitary
algebras su(p,q) of the Cartan series A_l and the pseudo-unitary algebras
u(p,q), are completely determined and classified for arbitrary p,q. In addition
to the su(p,q) and u({p,q}) algebras, whose second cohomology group is well
known to be trivial, each family includes many non-semisimple algebras; their
central extensions, which are explicitly given, can be classified into three
types as far as their properties under contraction are involved. A closed
expression for the dimension of the second cohomology group of any member of
these families of algebras is given.


title: On the interrelation between Gibbs hypotheses and symmetry postulate

abstract:
  The question of the origin of the Gibbs-factorials is reconsidered. It is
argued, using the example of the Brownian motion, that their appearance in
classical statistical calculations cannot in general be traced back to the
symmetry postulate of quantum mechanics as often assumed.


title: Local Fractional Derivatives and Fractal Functions of Several Variables

abstract:
  The notion of a local fractional derivative (LFD) was introduced recently for
functions of a single variable. LFD was shown to be useful in studying
fractional differentiability properties of fractal and multifractal functions.
It was demonstrated that the local Holder exponent/ dimension was directly
related to the maximum order for which LFD existed. We have extended this
definition to directional-LFD for functions of many variables and demonstrated
its utility with the help of simple examples.


title: Combinatorics, wreath products, finite space groups and magnetism

abstract:
  In this lecture some mathematical tools necessary for a proper description of
the Heisenberg antiferromagnet are presented. We would like to point out
differences between ferro- and antiferromagnetic cases of Heisenberg
Hamiltonian for finite spin systems. The ground-state properties are discussed.


title:
Algebraic approach to vibrational spectra of tetrahedral molecules: a
  case study of silicon tetrafluoride

abstract:
  Both the stretch and bend vibrational spectrum and the intensity of infrared
transitions in a tetrahedral molecule are studied in a U(2) algebraic model,
where the spurious states in the model Hamiltonian and the wavefunctions are
exactly removed. As an example, we apply the model to silicon tetrafluoride
SiF$_4$.


title:
U(2) algebraic model applied to stretching vibrational spectra of
  tetrahedral molecules

abstract:
  The highly excited stretching vibrational energy levels and the intensities
of infrared transitions in tetrahedral molecules are studied in a U(2)
algebraic model. Its applications to silane and silicon tetrafluoride are
presented with smaller standard deviations than those of other models.


title: The ground state of the Lithium atom in strong magnetic fields

abstract:
  The ground and some excited states of the Li atom in external uniform
magnetic fields are calculated by means of our 2D mesh Hartree-Fock method for
field strengths ranging from zero up to 2.35 10^8 T. With increasing field
strength the ground state undergoes two transitions involving three different
electronic configurations: for weak fields the ground state configuration
arises from the field-free 1s^22s configuration, for intermediate fields from
the 1s^22p_{-1} configuration and in high fields the 1s2p_{-1}3d_{-2}
electronic configuration is responsible for the properties of the atom. The
transition field strengths are determined. Calculations on the ground state of
the Li+ ion allow us to describe the field-dependent ionization energy of the
Li atom. Some general arguments on the ground states of multi-electron atoms in
strong magnetic fields are provided.


title: Generation of ultra-short light pulses by a rapidly ionizing thin foil

abstract:
  A thin and dense plasma layer is created when a sufficiently strong laser
pulse impinges on a solid target. The nonlinearity introduced by the
time-dependent electron density leads to the generation of harmonics. The pulse
duration of the harmonic radiation is related to the risetime of the electron
density and thus can be affected by the shape of the incident pulse and its
peak field strength. Results are presented from numerical
particle-in-cell-simulations of an intense laser pulse interacting with a thin
foil target. An analytical model which shows how the harmonics are created is
introduced. The proposed scheme might be a promising way towards the generation
of attosecond pulses.
  PACS number(s): 52.40.Nk, 52.50.Jm, 52.65.Rr


title:
Miron's Generalizations of Lagrange and Finsler Geometries: a
  Self-Consistent Approach to Locally Anisotropic Gravity

abstract:
  Radu Miron's approach to modelling of generalized Lagrange, Finsler and
Kaluza-Klein spaces on vector (super) bundles provided with compatible
nonlinear and distinguished connections and metric structures is discussed in
connection with the theory of locally anisotropic field interactions and
strings.


title:
Radiation Reaction in Classical Electrodynamics: the Case of Rotating
  Charged Sphere

abstract:
  In classical electrodynamics for rotating with variable angular velocity
charged rigid sphere are found: the exact values of electromagnetic fields, the
flux of radiating energy and the exact integral equation of rotation including
the terms of self-rotation. The analysis of this eq. shows that on one hand,
there is no "runaway" solutions, peculiar to the Lorentz-Dirac eq. of radiating
point particle, on the other hand, there appear new problems, among them is the
nonexistence of solution for some external moments of force.


title:
Detuning Induced Effects: Symmetry-Breaking Bifurcations in Dynamic
  Model of One-Mode Laser

abstract:
  The concept of broken symmetry is used to study bifurcations of equilibria
and dynamical instabilities in dynamic model of one-mode laser (nonresonant
complex Lorenz model) on the basis of modified Hopf theory. It is shown that an
invariant set of stationary points bifurcates into an invariant torus
(doubly-periodic branching solution). Influence of the symmetry breaking on
stability of branching solutions is investigated as a function of detuning. The
invariant torus is found to be stable under the detuning exceeds its critical
value, so that dynamically broken symmetry results in the apprearance of
low-frequency Goldstone-type mode. If the detuning then goes downward and
pumping is kept above the threshold, numerical analysis reveals that after a
cascade of period-doublings the strange Lorenz attractor is formed at small
values of detuning. It is found that there are three types of the system
behavior as pumping increases depending on the detuning. Quantum counterpart of
the complex Lorenz model is discussed.

categories: physics.optics chao-dyn math-ph math.MP nlin.CD


title:
Momentum Maps and Classical Relativistic Fields. Part I: Covariant Field
  Theory

abstract:
  This is the first paper of a five part work in which we study the Lagrangian
and Hamiltonian structure of classical field theories with constraints. Our
goal is to explore some of the connections between initial value constraints
and gauge transformations in such theories (either relativistic or not). To do
this, in the course of these four papers, we develop and use a number of tools
from symplectic and multisymplectic geometry. Of central importance in our
analysis is the notion of the ``energy-momentum map'' associated to the gauge
group of a given classical field theory. We hope to demonstrate that many
different and apparently unrelated facets of field theories can be thereby tied
together and understood in an essentially new way.
  In Part I we develop some of the basic theory of classical fields from a
spacetime covariant viewpoint. We begin with a study of the covariant
Lagrangian and Hamiltonian formalisms, on jet bundles and multisymplectic
manifolds, respectively. Then we discuss symmetries, conservation laws, and
Noether's theorem in terms of ``covariant momentum maps.''


title:
Finite Mass Effect on Two Photon Processes in Hydrogenic Systems:
  Effective Scalar Photon Interaction

abstract:
  We consider a hydrogenic system with a nucleus of finite mass. The coupling
of the radiation field to the center of mass motion gives rise to an effective
scalar type coupling. This induced scalar photon interaction emerges as a
correction in competition with the usual multipole interactions. This effect is
particularly important in positronium where the electric quadrupole interaction
is totally suppressed. We illustrate this effect with the two-photon decay of
metastable hydrogenic systems.


title:
Do We See the ``Dark Clouds'' Again? --- On Some Puzzles in Contemporary
  Physics

abstract:
  Some conceptual problems in physics are discussed. Do we need a change in the
concept of matter structure? Why the ``$i=\sqrt{-1}$'' is introduced to quantum
mechanics (QM) essentially? What is the relation between QM and special
relativity (SR)? Could we modify the stationary Schr$\ddot{\rm o}$dinger
equation in conformity with SR? How can a particle acquire a mass? We propose
some tentative answer. Their philosophical implications are emphasized.


title: The Hierarchy of Fast Motions in Protein Dynamics

abstract:
  For many biological applications of molecular dynamics (MD) the importance of
good sampling in conformational space makes it necessary to eliminate the
fastest motions from the system in order to increase the time step. An accurate
knowledge of these motions is a necessary prerequisite for such efforts. It is
known that harmonic vibrations of bond lengths and bond angles produce the
highest frequencies in proteins. There are also fast anharmonic motions, such
as inter-atomic collisions, which are probably most important when bond lengths
and bond angles are fixed. However, the specific time scales corresponding to
all these limitations are not known precisely. In order to clarify the above
issue this paper analyses time step limiting factors in a series of numerical
tests by using an internal coordinate molecular dynamics approach, which allows
chosen internal coordinates to be frozen. It is found that, in proteins, there
is a rather complicated hierarchy of fast motions, with both harmonic and
anharmonic effects mixed together at several close time scales. Non-bonded
interactions, notably strong hydrogen bonding, create locally distributed
normal modes with frequencies similar to those of bond stretching between
non-hydrogen atoms. They also impose ubiquitous anharmonic limitations starting
from rather small step sizes. With fixed standard amino acid geometry,
rotations of hydrogen bonded hydroxyl groups limit time steps at the 5 fsec
level. The next important limitation occurs around 10 fsec and is created by
collisions between non-hydrogen atoms.

categories: physics.comp-ph physics.bio-ph physics.chem-ph q-bio


title: Constrained Systems and Analytical Mechanics in Spases with Torsion

abstract:
  A system with anholonomic constraints where the trajectories of physical
degrees of freedom are autoparallels on a manifold equipped with a general
Cartan connection is discussed. A variational principle for the autoparallel
trajectories is derived from the d'Alambert-Lagrange principle for anholonomic
constrained systems. A geometrical (coordinate-independent) formulation of the
variational principle is given. Its relation to Sedov's anholonomic variational
principle for dissipative systems and to Poincar\'e's variational principle in
anholonomic reference frames is established. A modification of Noether's
theorem due to the torsion force is studied. A non-local action whose extrema
contain the autoparallels is proposed. The action can be made local by adding
auxiliary degrees of freedom coupled to the original variables in a special
way.


title: Speculations on the Evans-Comay Discussion

abstract: The Reply to G. W. Bruhn is added.


title: Vladimir Gribov (BH)

abstract: In memoria of Vladimir Naumovich Gribov

categories: physics.hist-ph cond-mat.supr-con hep-ph hep-th physics.soc-ph


title: Universal Statistical Behavior of Neural Spike Trains

abstract:
  We construct a model that predicts the statistical properties of spike trains
generated by a sensory neuron. The model describes the combined effects of the
neuron's intrinsic properties, the noise in the surrounding, and the external
driving stimulus. We show that the spike trains exhibit universal statistical
behavior over short times, modulated by a strongly stimulus-dependent behavior
over long times. These predictions are confirmed in experiments on H1, a
motion-sensitive neuron in the fly visual system.


title: A crystal base for the genetic code

abstract:
  The quantum enveloping algebra U_q(sl(2) \oplus sl(2)) in the limit q \to 0
is proposed as a symmetry algebra for the genetic code. In this approach the
triplets of nucleotids or codons in the DNA chain are classified in crystal
bases, tensor product of U_{q \to 0}(sl(2) \oplus sl(2)) representations. Such
a construction might be compared to the baryon classification from quark
building blocks in elementary particles physics, one of the main differences
standing in the property of a crystal base to provide a natural order in the
state constituents, this order being crucial in the codon. Then an operator
ensuring the correspondence codon/amino-acid can be constructed out of the
above algebra. It will be called the reading operator, and be such that two
codons relative to the same (resp. different) amino-acid(s) acquire the same
(resp. different) eigenvalue(s).


title:
Simulating temporal evolution of pressure in two-phase flow in porous
  media

abstract:
  We have simulated the temporal evolution of pressure due to capillary and
viscous forces in two-phase drainage in porous media. We analyze our result in
light of macroscopic flow equations for two-phase flow. We also investigate the
effect of the trapped clusters on the pressure evolution and on the effective
permeability of the system. We find that the capillary forces play an important
role during the displacements for both fast and slow injection rates and both
when the invading fluid is more or less viscous than the defending fluid. The
simulations are based on a network simulator modeling two-phase drainage
displacements on a two-dimensional lattice of tubes.


title:
Insufficiency of Available Data on the Behaviour of the Meanlives of
  Unstable Hadrons with Energy

abstract:
  We review the available evidence according to which physical media alter the
Minkowskian spacetime with consequential alteration of the speed of light; we
point out the apparent emergence of superluminal speeds within the hyperdense
hadrons; and we point out the lack of conclusive character of the available
related measure, those on the behaviour of the meanlives of unstable kaons with
energy.


title: Resonant Above-Threshold Ionization Peaks at Quantized Intensities

abstract:
  We suggest that electron-laser interactions can give rise to resonance
phenomena as the intensity varies. A new QED perturbation theory is developed,
in which the coupling between an electron and the second quantized laser mode
is treated nonperturbatively. We predict, for example, the above-threshold
ionization rate shows peaks at intensities with integer ponderomotive
parameter. Such quantum resonance effects may be exploited to calibrate laser
intensities in appropriate range.


title: On quantization of mass and electrical charge

abstract:
  Suggested non-linear, non-gauge modification of the Maxwell theory of
electromagnetism based on correlation between electromagnetic potential, $A_a$,
and metric, $g_{ab}$, such that tensor $G_{ab} = g_{ab} - l^2{A}_a{A}_b$
represents observable metric. Here $l$ is fundamental constant of the theory.
The idea, that the charge density of elementary particle could be a function of
electromagnetic potential and background metric (only) is accepted, and
specific model of the density is considered. Due to non-linearity of equations,
one obtains solutions corresponding to quantized electrical charge with
spectrum $q_{n} = {{2n}\over3}e$ and $q'_{n} = -{(2n+1)\over3}e$, where $n = 0,
1, 2, ...$


title:
Photodetachment study of He^- quartet resonances below the He(n=3)
  thresholds

abstract:
  The photodetachment cross section of He^- has been measured in the photon
energy range 2.9 eV to 3.3 eV in order to investigate doubly excited states.
Measurements were made channel specific by selectively detecting the residual
He atoms left in a particular excited state following detachment. Three
Feshbach resonances were found in the He(1s2p ^3P)+e^-(epsilon p) partial cross
section: a ^4S resonance below the He(1s3s ^3S) threshold and two ^4P
resonances below the He(1s3p ^3P) threshold. The measured energies of these
doubly excited states are 2.959260(6) eV, 3.072(7) eV and 3.26487(4) eV. The
corresponding widths are found to be 0.20(2) meV, 50(5) meV and 0.61(5) meV.
The measured energies agree well with recent theoretical predictions for the
1s3s4s ^4S, 1s3p^2 ^4P and 1s3p4p ^4P states, respectively, but the widths
deviate noticeably from calculations for 1s3p^2 ^4P and 1s3p4p ^4P states.


title:
A 10 MHz beam counter and a multiplicity detector for the E864
  spectrometer

abstract:
  The E864 experiment at BNL requires a beam counter and multiplicity detector
system that can perform at an incident beam rate of 10^7 Au ions per second. We
have developed and tested a 150 micrometer thick quartz Cherenkov beam counter
and a scintillator based multiplicity-trigger counter during the first run of
this experiment in 1994. We obtained a time resolution of 78 ps for the beam
counter at an incident beam rate 5 x 10^5 Hz and 100 ps at a rate of 1 x 10^7
Hz. Pulse height discrimination is used to obtain a minimum bias and a 10%
centrality trigger from the multiplicity detectors. The multiplicity counter
has a time resolution of 250 ps.


title: Stark-Induced Electric Dipole Amplitudes for Hyperfine Transitions

abstract:
  Stark-induced electric dipole amplitudes between states of the same nominal
parity can be important in experiments to observe parity nonconservation in
atoms. The Stark-induced E1 amplitudes are expressed in terms of an irreducible
spherical-tensor decomposition. This formalism is applied to the specific case
of transitions between hyperfine sublevels of a single atomic state. It is
shown that in the ground states of alkali atoms, such transitions are
suppressed by many orders of magnitude relative to naive expectations.


title:
Progressive internal gravity waves with bounded upper surface climbing a
  triangular obstacle

abstract:
  In this paper we discuss a theoretical model for the interfacial profiles of
progressive non-linear waves which result from introducing a triangular
obstacle, of finite height, attached to the bottom below the flow of a
stratified, ideal, two layer fluid, bounded from above by a rigid boundary. The
derived equations are solved by using a nonlinear perturbation method. The
dependence of the interfacial profile on the triangular obstacle size, as well
as its dependence on some flow parameters, such as the ratios of depths and
densities of the two fluids, have been studied.


title: Numerical observation of non-axisymmetric vesicles in fluid membranes

abstract:
  By means of Surface Evolver (Exp. Math,1,141 1992), a software package of
brute-force energy minimization over a triangulated surface developed by the
geometry center of University of Minnesota, we have numerically searched the
non-axisymmetric shapes under the Helfrich spontaneous curvature (SC) energy
model. We show for the first time there are abundant mechanically stable
non-axisymmetric vesicles in SC model, including regular ones with intrinsic
geometric symmetry and complex irregular ones. We report in this paper several
interesting shapes including a corniculate shape with six corns, a
quadri-concave shape, a shape resembling sickle cells, and a shape resembling
acanthocytes. As far as we know, these shapes have not been theoretically
obtained by any curvature model before. In addition, the role of the
spontaneous curvature in the formation of irregular crenated vesicles has been
studied. The results shows a positive spontaneous curvature may be a necessary
condition to keep an irregular crenated shape being mechanically stable.


title: Muon Dynamics in a Toroidal Sector Magnet

abstract:
  We present a Hamiltonian formulation of muon dynamics in toroidal sector
solenoids (bent solenoids)


title:
Statistics of electromagnetic transitions as a signature of chaos in
  many-electron atoms

abstract:
  Using a configuration interaction approach we study statistics of the dipole
matrix elements (E1 amplitudes) between the 14 lower odd states with J=4 and
21st to 100th even states with J=4 in the Ce atom (1120 lines). We show that
the distribution of the matrix elements is close to Gaussian, although the
width of the Gaussian distribution, i.e. the root-mean-square matrix element,
changes with the excitation energy. The corresponding line strengths are
distributed according to the Porter-Thomas law which describes statistics of
transition strengths between chaotic states in compound nuclei. We also show
how to use a statistical theory to calculate mean squared values of the matrix
elements or transition amplitudes between chaotic many-body states. We draw
some support for our conclusions from the analysis of the 228 experimental line
strengths in Ce [J. Opt. Soc. Am. v. 8, p. 1545 (1991)], although direct
comparison with the calculations is impeded by incompleteness of the
experimental data. Nevertheless, the statistics observed evidence that highly
excited many-electron states in atoms are indeed chaotic.

categories: physics.atom-ph chao-dyn cond-mat.mes-hall nlin.CD


title: Two-dimensional Stationary Wake Fields in Vortexfree Cold Plasma. I

abstract:
  Present paper is devoted to formulation of the system of the master equations
of the problem and analytical considerations of the limiting cases, which have
an exact solutions (transversal and longitudinal flat bunches, linear approxim-
ation). Presented consideration gives some hints to the construction of proper
algorithm for numerical calculations.


title: Muon Collider: Introduction and status

abstract:
  Parameters are given of machines with center-of-mass (CoM) energies of 3 TeV
and 400 GeV but, besides a comment on neutrino radiation, the paper
concentrates on progress on the design of a machine to operate at a light Higgs
mass, assumed, for this study, to be 100 GeV (CoM).


title:
RAMPEX - a new spin experiment (presented for HELION97, 20-24 Jan 1997,
  Kobe, Japan)

abstract:
  RAMPEX - Russian-AMerican Polarization EXperiment - is dedicated to studies
of one-spin asymmetries which have twist-3 and also twist-2 origin, in hard and
semi-hard inclusive processes on the polarized propane-diol target. A special
consideration has been given for the prospects of using polarized 3He target.
The studies will be performed at the Serpukhov accelerator at 70 GeV/c (proton
beam) and 40 GeV/c (pi- beam).


title: Fractal Diffraction Grating

abstract:
  We consider an optical diffraction grating in which the spatial distribution
of open slits forms a fractal set. The Fraunhofer diffraction patterns through
the fractal grating are obtained analytically for the simplest triad Cantor
type and its generalized version. The resulting interference patterns exhibit
characteristics of the original fractals and their scaling properties.


title: The steady state of a pumped and damped atom laser

abstract:
  This paper has been withdrawn, as further work has shown that an atom laser
as described by the model herein does not have a steady state, so it doesn't
matter much what it would look like.


title:
The Anderson model of localization: a challenge for modern eigenvalue
  methods

abstract:
  We present a comparative study of the application of modern eigenvalue
algorithms to an eigenvalue problem arising in quantum physics, namely, the
computation of a few interior eigenvalues and their associated eigenvectors for
the large, sparse, real, symmetric, and indefinite matrices of the Anderson
model of localization. We compare the Lanczos algorithm in the 1987
implementation of Cullum and Willoughby with the implicitly restarted Arnoldi
method coupled with polynomial and several shift-and-invert convergence
accelerators as well as with a sparse hybrid tridiagonalization method. We
demonstrate that for our problem the Lanczos implementation is faster and more
memory efficient than the other approaches. This seemingly innocuous problem
presents a major challenge for all modern eigenvalue algorithms.


title: A Perturbative Approach to the Relativistic Harmonic Oscillator

abstract:
  A quantum realization of the Relativistic Harmonic Oscillator is realized in
terms of the spatial variable $x$ and ${\d\over \d x}$ (the minimal canonical
representation). The eigenstates of the Hamiltonian operator are found (at
lower order) by using a perturbation expansion in the constant $c^{-1}$. Unlike
the Foldy-Wouthuysen transformed version of the relativistic hydrogen atom,
conventional perturbation theory cannot be applied and a perturbation of the
scalar product itself is required.


title: The Rayleigh-Taylor Instability of Transition Layer

abstract:
  New types of symmetry for the Rayleigh equation are found. For small Atwood
number, an analytic solution is obtained for a smoothly varying density
profile. It is shown that a transition layer with a finite width can undergo
some kind of stratification.


title: Invariant tensors and Casimir operators for simple compact Lie groups

abstract:
  The Casimir operators of a Lie algebra are in one-to-one correspondence with
the symmetric invariant tensors of the algebra. There is an infinite family of
Casimir operators whose members are expressible in terms of a number of
primitive Casimirs equal to the rank of the underlying group. A systematic
derivation is presented of a complete set of identities expressing
non-primitive symmetric tensors in terms of primitive tensors. Several examples
are given including an application to an exceptional Lie algebra.


title:
Possible Mechanism of Formation and Stability of Anomalous States of
  Water

abstract:
  We examine the physical processes which are involved in the formation and
stability of the anomalous states of water reported recently. The initial step
of adding a small amount of ionic compound XY to pure water leads to the
formation of water clusters (X^+)(H2O)_n and (Y^-)(H2O)_n with n>>1. The
structure of the cluster around the ion depends strongly on the equation of
state. We explore the consequences of possible polymorphic states of H2O in the
liquid phase at room temperature. If there are low-lying polymorphic states,
the local dipole moment and the local density will change discontinuously as a
function of the radial distance from the ion, and regions of different
polymorphic states will be found at different separations from the ion.
Fragmentation of the cluster by vigorous shaking may break up the cluster into
small domains to allow subsequent coalescence of these domains or the growth of
the domains as seeds to form greater domains of polymorphic states. Further
experimental and theoretical analyses are needed to study these pictures.


title: A Lanczos algorithm for linear response

abstract:
  An iterative algorithm is presented for solving the RPA equations of linear
response. The method optimally computes the energy-weighted moments of the
strength function, allowing one to match the computational effort to the
intrinsic accuracy of the basic mean-field approximation, avoiding the problem
of solving very large matrices. For local interactions, the computational
effort for the method scales with the number of particles N_p as O(N_p^3).


title:
From Design to Production Control Through the Integration of Engineering
  Data Management and Workflow Management Systems

abstract:
  At a time when many companies are under pressure to reduce "times-to-market"
the management of product information from the early stages of design through
assembly to manufacture and production has become increasingly important.
Similarly in the construction of high energy physics devices the collection of
(often evolving) engineering data is central to the subsequent physics
analysis. Traditionally in industry design engineers have employed Engineering
Data Management Systems (also called Product Data Management Systems) to
coordinate and control access to documented versions of product designs.
However, these systems provide control only at the collaborative design level
and are seldom used beyond design. Workflow management systems, on the other
hand, are employed in industry to coordinate and support the more complex and
repeatable work processes of the production environment. Commercial workflow
products cannot support the highly dynamic activities found both in the design
stages of product development and in rapidly evolving workflow definitions. The
integration of Product Data Management with Workflow Management can provide
support for product development from initial CAD/CAM collaborative design
through to the support and optimisation of production workflow activities. This
paper investigates this integration and proposes a philosophy for the support
of product data throughout the full development and production lifecycle and
demonstrates its usefulness in the construction of CMS detectors.


title: Ultra-low energy scattering of a He atom off a He dimer

abstract:
  We present a new, mathematically rigorous, method suitable for bound state
and scattering processes calculations for various three atomic or molecular
systems where the underlying forces are of a hard-core nature. We employed this
method to calculate the binding energies and the ultra-low energy scattering
phase shifts below as well as above the break-up threshold for the three
He-atom system. The method is proved to be highly successful and suitable for
solving the three-body bound state and scattering problem in configuration
space and thus it paves the way to study various three-atomic systems, and to
calculate important quantities such as the cross-sections, recombination rates
etc.


title: Oscillator strengths with pseudopotentials

abstract:
  The time-dependent local-density approximation (TDLDA) is shown to remain
accurate in describing the atomic response of IB elements under the additional
approximation of using pseudopotentials to treat the effects of core electrons.
This extends the work of Zangwill and Soven who showed the utility of the
all-electron TDLDA in the atomic response problem.


title: Lateral Drift of Free Electrons

abstract:
  An experiment was conducted with the intent to detect the effect, if any, of
the hypothetical centricoris acceleration of freely spinning electrons by the
use of an electromagnet with its conductor firmly clamped between its two
attracting magnetic plates. It was theorized that the freely spinning electrons
were uniformly oriented by the magnetic field, and the induced centricoris
accelerations should have their combined effect on the special electromagnet.
This electromagnet was installed on a digital scale. The effect of the expected
centricoris acceleration showed up, depending on the direction of the applied
electric potential, as the about +/- 0.05 gr variation of the electromagnet's
135.2 gr weight. Another experiment confirmed that the observed weight
variations must be attributed to the centricoris acceleration, to the lateral
drifts of the conductor's free electrons.


title:
Density probability distribution in one-dimensional polytropic gas
  dynamics

abstract:
  We discuss the generation and statistics of the density fluctuations in
highly compressible polytropic turbulence, based on a simple model and
one-dimensional numerical simulations. Observing that density structures tend
to form in a hierarchical manner, we assume that density fluctuations follow a
random multiplicative process. When the polytropic exponent $\gamma$ is equal
to unity, the local Mach number is independent of the density, and our
assumption leads us to expect that the probability density function (PDF) of
the density field is a lognormal. This isothermal case is found to be singular,
with a dispersion $\sigma_s^2$ which scales like the square turbulent Mach
number $\tilde M^2$, where $s\equiv \ln \rho$ and $\rho$ is the fluid density.
This leads to much higher fluctuations than those due to shock jump relations.
  Extrapolating the model to the case $\gamma \not =1$, we find that, as the
Mach number becomes large, the density PDF is expected to asymptotically
approach a power-law regime, at high densities when $\gamma<1$, and at low
densities when $\gamma>1$. This effect can be traced back to the fact that the
pressure term in the momentum equation varies exponentially with $s$, thus
opposing the growth of fluctuations on one side of the PDF, while being
negligible on the other side. This also causes the dispersion $\sigma_s^2$ to
grow more slowly than $\tilde M^2$ when $\gamma\not=1$. In view of these
results, we suggest that Burgers flow is a singular case not approached by the
high-$\tilde M$ limit, with a PDF that develops power laws on both sides.

categories: physics.flu-dyn astro-ph chao-dyn nlin.CD


title:
An ab initio path integral Monte Carlo simulation method for molecules
  and clusters: application to Li_4 and Li_5^+

abstract:
  A novel method for simulating the statistical mechanics of molecular systems
in which both nuclear and electronic degrees of freedom are treated quantum
mechanically is presented. The scheme combines a path integral description of
the nuclear variables with a first-principles adiabatic description of the
electronic structure. The electronic problem is solved for the ground state
within a density functional approach, with the electronic orbitals expanded in
a localized (Gaussian) basis set. The discretized path integral is computed by
a Metropolis Monte Carlo sampling technique on the normal modes of the
isomorphic ring-polymer. An effective short-time action correct to order
$\tau^4$ is used. The validity and performance of the method are tested in two
small Lithium clusters, namely Li$_4$ and Li$_5^+$. Structural and electronic
properties computed within this fully quantum-mechanical scheme are presented
and compared to those obtained within the classical nuclei approximation.
Quantum delocalization effects are significant but tunneling turns out to be
irrelevant at low temperatures.

categories: physics.comp-ph cond-mat.stat-mech physics.atm-clus physics.chem-ph


title: Computing the real-time Green's Functions of large Hamiltonian matrices

abstract:
  A numerical method is developed for calculating the real time Green's
functions of very large sparse Hamiltonian matrices, which exploits the
numerical solution of the inhomogeneous time-dependent Schroedinger equation.
The method has a clear-cut structure reflecting the most naive definition of
the Green's functions, and is very suitable to parallel and vector
supercomputers. The effectiveness of the method is illustrated by applying it
to simple lattice models. An application of this method to condensed matter
physics will be found in H. Tanaka, Phys. PRB 57, 2168 (1998).


title: Dynamics of n-alkanes: Comparison to Rouse Model

abstract:
  The crossover to Rouse-like behavior for the self-diffusion constant D, the
viscosity $\eta$, and the equilibrium structural statistics of n-alkanes $(6
\le n \le 66)$ is studied numerically. For small n the chains are non-Gaussian
and the mean squared end-to-end distance $R^2$ is greater than $R_G^2$, where
$R_g^2$ is the mean squared radius of gyration. As n increases, $R^2/R_G^2 \to
6(1+b/n)$, where b depends on the interaction model. At constant density, the
Rouse model is used to extract the monomeric friction coefficient $\zeta$ and
the viscosity $\eta$ independently from the diffusion constant D and the
longest relaxation time $\tau_R$. $\zeta_D$ extracted from D is nearly
independent of chain length while $\zeta_\tau$ obtained from $\tau_R$ is much
larger than $\zeta_D$ for small n. The viscosity measured in a non-equilibrium
molecular dynamics simulation is closely approximated by the value of $\eta$
determined from $\tau_R$ while $\eta$ inferred from D is smaller for small n.
For $n\agt 60$, the two estimates for both $\zeta$ and $\eta$ agree as
predicted from the Rouse model. D calculated from three interaction models is
studied for increasing $n$ and compared to experimental data.


title: Scaling Laws and Similarity Detection in Sequence Alignment with Gaps

abstract:
  We study the problem of similarity detection by sequence alignment with gaps,
using a recently established theoretical framework based on the morphology of
alignment paths. Alignments of sequences without mutual correlations are found
to have scale-invariant statistics. This is the basis for a scaling theory of
alignments of correlated sequences. Using a simple Markov model of evolution,
we generate sequences with well-defined mutual correlations and quantify the
fidelity of an alignment in an unambiguous way. The scaling theory predicts the
dependence of the fidelity on the alignment parameters and on the statistical
evolution parameters characterizing the sequence correlations. Specific
criteria for the optimal choice of alignment parameters emerge from this
theory. The results are verified by extensive numerical simulations.


title: A Start-Timing Detector for the Collider Experiment PHENIX at RHIC-BNL

abstract:
  We describe a start-timing detector for the PHENIX experiment at the
relativistic heavy-ion collider RHIC. The role of the detector is to detect a
nuclear collision, provide precise time information with an accuracy of 50ps,
and determine the collision point along the beam direction with a resolution of
a few cm. Technical challenges are that the detector must be operational in a
wide particle-multiplicity range in a high radiation environment and a strong
magnetic field. We present the performance of the prototype and discuss the
final design of the detector.


title:
Nonlinear Radiation Pressure and Stochasticity in Ultraintense Laser
  Fields

abstract:
  The radiation force on a single electron in an ultraintense plane wave ($a =
eE/mc\omega \sim 1$) is calculated and shown to be proportional to $a^4$ in the
high-$a$ limit for arbitrary waveform and polarization. The cyclotron motion of
an electron in a constant magnetic field and an ultraintense plane wave is
numerically found to be quasiperiodic even in the high-$a$ limit if the
magnetic field is not too strong, as suggested by previous analytical work. A
strong magnetic field causes highly chaotic electron motion and the boundary of
the highly chaotic region of parameter space is determined numerically.
Applications to experiments and astrophysics are briefly discussed.


title: Transverse quasilinear relaxation in inhomogeneous magnetic field

abstract:
  Transverse quasilinear relaxation of the cyclotron-Cherenkov instability in
the inhomogeneous magnetic field of pulsar magnetospheres is considered. We
find quasilinear states in which the kinetic cyclotron-Cherenkov instability of
a beam propagating through strongly magnetized pair plasma is saturated by the
force arising in the inhomogeneous field due to the conservation of the
adiabatic invariant. The resulting wave intensities generally have nonpower law
frequency dependence, but in a broad frequency range can be well approximated
by the power law with the spectral index -2. The emergent spectra and fluxes
are consistent with the one observed from pulsars.


title: Integration in General Relativity

abstract:
  This paper presents a brief but comprehensive introduction to certain
mathematical techniques in General Relativity. Familiar mathematical procedures
are investigated taking into account the complications of introducing a non
trivial space-time geometry. This transcript should be of use to the beginning
student and assumes only very basic familiarity with tensor analysis and modern
notation. This paper will also be of use to gravitational physicists as a quick
reference.


title: Question: Negative Group Delays and Action-at-a-Distance

abstract:
  We comment on the paper by M. W. Mitchell and R. Y. Chiao, ``Causality and
negative group delay in a simple bandpass amplifier", Am. J. Phys. 66 (1),
14-19 (1998).


title:
Space-Time Variation of Physical Constants and Relativistic Corrections
  in Atoms

abstract:
  Detection of high-redshift absorption in the optical spectra of quasars have
provided a powerful tool to measure spatial and temporal variations of physical
``constants'' in the Universe. It is demonstrated that high sensitivity to the
variation of the fine structure constant alpha can be obtained from a
comparison of the spectra of heavy and light atoms (or molecules). We have
performed calculations for the pair FeII and MgII for which accurate quasar and
laboratory spectra are available. A possibility of $10^5$ times enhanced
effects of the fundamental constants variation suitable for laboratory
measurements is also discussed.


title:
Contribution to inertial mass by reaction of the vacuum to accelerated
  motion

abstract:
  We present an approach to the origin of inertia involving the electromagnetic
component of the quantum vacuum and propose this as an alternative to Mach's
principle. Preliminary analysis of the momentum flux of the classical
zero-point radiation impinging on accelerated objects as viewed by an inertial
observer suggests that the resistance to acceleration attributed to inertia may
be at least in part a force of opposition originating in the vacuum. This
analysis avoids the ad hoc modeling of particle-field interaction dynamics used
previously to derive a similar result. This present approach is not dependent
upon what happens at the particle point, but on how an external observer
assesses the kinematical characteristics of the zero-point radiation impinging
on the accelerated object. A relativistic form of the equation of motion
results from the present analysis. Its covariant form yields a simple result
that may be interpreted as a contribution to inertial mass. Our approach is
related by the principle of equivalence to Sakharov's conjecture of a
connection between Einstein action and the vacuum. The argument presented may
thus be construed as a descendant of Sakharov's conjecture by which we attempt
to attribute a mass-giving property to the electromagnetic component -- and
possibly other components-- of the vacuum. In this view the physical momentum
of an object is related to the radiative momentum flux of the vacuum
instantaneously contained in the characteristic proper volume of the object.
The interaction process between the accelerated object and the vacuum (akin to
absorption or scattering of electromagnetic radiation) appears to generate a
physical resistance (reaction force) to acceleration suggestive of what has
been historically known as inertia.


title: Inertia as reaction of the vacuum to accelerated motion

abstract:
  It was proposed by Haisch, Rueda and Puthoff (Phys. Rev. A, 49, 678, 1994)
that the inertia of matter could be interpreted at least in part as a reaction
force originating in interactions between the electromagnetic zero-point field
(ZPF) and the elementary charged consitutents (quarks and electrons) of matter.
Within the limited context of that analysis, it appeared that Newton's equation
of motion, f=ma, could be inferred from Maxwell's equations as applied to the
ZPF, i.e. the stochastic electrodynamics (SED) version of the quantum vacuum.
We report on a new approach which avoids the ad hoc particle-field interaction
model (Planck oscillator) of that analysis, as well as its concomitant
formulational complexity. Instead, it is shown that a non-zero ZPF momentum
flux arises naturally in accelerating coordinate frames from the standard
relativistic transformations of electromagnetic fields. Scattering of this ZPF
momentum flux by an object will yield a reaction force that may be interpreted
as a contribution to the object's inertia. This new formulation is properly
covariant yielding the relativistic equation of motion. Our approach is related
by the principle of equivalence to Sakharov's conjecture of a connection
between Einstein action and the vacuum. If correct, this concept would
substitute for Mach's principle and imply that no further mass-giving
Higgs-type fields may be required to explain the inertia of material objects,
although extensions to include the zero-point fields of the other fundamental
interactions may be necessary for a complete theory of inertia.


title:
Scattering Integral Equations for Diffusive Waves. Detection of Objects
  Buried in Diffusive Media in the Presence of Interfaces

abstract: This paper has been withdrawn by the authors until some changes are made.


title: Electromagnetic Waves in the Vacuum with Torsion and Spin

abstract:
  Exact radiative wave solutions to the classical homogeneous Maxwell equations
in the vacuum have been found that are not transverse, exhibit both torsion and
spin, and for which the second Poincare invariant, E.B, is not zero. Two four
component rank 3 tensors of spin current and torsion are constructed on
topological grounds. The divergence of each pseudo vector generates the
Poincare invariants of the electromagnetic system.


title:
IBM PC running Solaris x86 as an affordable NFS file server platform for
  a workgroup

abstract:
  The possibility of using an IBM PC-compatible computer as an NFS file server
for a moderate-size workgroup has been explored. A pilot project currently
under way at LBNL has proven that this platform does indeed provide a viable
alternative to commercially available file servers at a fraction of the cost
without significant sacrifices in performance and reliability.
  From a $1,500 worth of hardware, we have built a Solaris x86 file server with
19.2 GB of disk space, expandable to 112 GB for another $6,200, which has
proven to be a worthy contender in performance to its proprietary counterparts.
The server has not exhibited any software of hardware problems during the four
months it has been in service. Overall, the platform appears to be well suited
to the needs of an experimental particle physics workgroup. We recommend it for
use in the BaBar collaboration.
  This paper focuses on aspects of building a properly configured dedicated
file server that are not adequately covered in the Solaris Installation and
System Administration guides, such as choosing right hardware and performance
optimization. Parts of it may also be of interest to prospective buyers of IBM
PC-compatible systems and to Solaris SPARC administrators.


title: Theory of hierarchical coupling

abstract: The paper has been withdrawn


title: Numerical simulations on Szilard's engine and information erasure

abstract:
  We present a computational model for Szilard's engine and the information
discarding process. Taking advantage of a fact that the one is essentially the
reversed cycle of the other, we can discuss the both by employing the same
model. Through numerical simulations we calculate the work extracted by the
engine and the heat generation in the information discarding process. It is
found that these quantities depend on some realistic ingredients, which means
that the work done by the engine is no longer canceled by the heat generation
in the information erasure.

categories: physics.class-ph chao-dyn cond-mat.stat-mech nlin.CD physics.gen-ph


title: Grasers based on particle accelerators and on lasers

abstract:
  Grasers based on a stimulated emission of gravitational radiation by
relativistic charged particle beams in external fields and on a conversion of
laser radiation into gravitational one in the magnetic fields as well as
detectors are discussed. A scheme of the gravitational radiation not
accompanied by an useless inaccessible by a value average power of the
electromagnetic radiation and a stimulation of the conversion of gravitons into
photons in gravitational detectors by an open resonator are considered.


title:
Universal Newton Time in Classical Electrodynamics. Elements of Physical
  Interpretation

abstract:
  It is shown that the universal Newton time may be introduced in the classical
electrodynamics. The statement results from an existence of the generalized
symmetry of Maxwell equations with respect to Galilei transformations
(physics/9701006). In the case of the extended Galilei transformations the
postulate of invariance of the speed of light may be made compatible with the
concept of the universal Newton time. Some physical consequences of the
extended Galilei symmetry are considered.


title: Historical Note on the Relativistic Theories of Electromagnetism

abstract:
  Quantum electrodynamics is the well-accepted theory. However, we feel it is
useful to look at formalisms that provide alternative ways to describe light,
because in the recent years the development of quantum field theories based
primarily on the gauge principle has encountered considerable difficulties.
There is a wide variety of generalized theories and they are characterized
mainly by the introduction of additional parameters and/or longitudinal modes
of electromagnetism. The Majorana-Oppenheimer form of electrodynamics, the
Sachs' theory of Elementary Matter, the analysis of the action-at-a-distance
concept, presented recently by Chubykalo and Smirnov-Rueda, and the analysis of
the claimed `longitudinality' of the antisymmetric tensor field after
quantization are reviewed in this essay. We also list recent advances in the
Weinberg 2(2J+1) formalism (which is built on First Principles) and in the
Majorana theory of neutral particles. These may serve as starting points for
constructing a quantum theory of light.


title: Phase Dynamics of Bose-Einstein Condensates: Losses versus Revivals

abstract:
  In the absence of losses the phase of a Bose-Einstein condensate undergoes
collapses and revivals in time due to elastic atomic interactions. As
experiments necessarily involve inelastic collisions, we develop a model to
describe the phase dynamics of the condensates in presence of collisional
losses. We find that a few inelastic processes are sufficient to damp the
revivals of the phase. For this reason the observability of phase revivals for
present experimental conditions is limited to condensates with a few hundreds
of atoms.


title: The nonlinear superposition principle and the Wei-Norman method

abstract:
  Group theoretical methods are used to study some properties of the Riccati
equation, which is the only differential equation admitting a nonlinear
superposition principle. The Wei-Norman method is applied to obtain the
associated differential equation in the group $SL(2,R)$. The superposition
principle for first order differential equation systems and Lie-Scheffers
theorem are also analysed from this group theoretical perspective. Finally, the
theory is applied in the solution of second order differential equations like
time-independent Schroedinger equation


title:
Exact field ionization rates in the barrier suppression-regime from
  numerical TDSE calculations

abstract:
  Numerically determined ionization rates for the field ionization of atomic
hydrogen in strong and short laser pulses are presented. The laser pulse
intensity reaches the so-called "barrier suppression ionization" regime where
field ionization occurs within a few half laser cycles. Comparison of our
numerical results with analytical theories frequently used shows poor
agreement. An empirical formula for the "barrier suppression ionization"-rate
is presented. This rate reproduces very well the course of the numerically
determined ground state populations for laser pulses with different length,
shape, amplitude, and frequency.
  Number(s): 32.80.Rm


title:
First experimental tests of the Peyrard-Bishop model applied to the
  melting of very short DNAs

abstract:
  The melting curves of short heterogeneous DNA chains in solution are
calculated on the basis of statistical thermodynamics and compared to
experiments. The computation of the partition function is based on the
Peyrard-Bishop hamiltonian, which has already been adopted in the theoretical
description of the melting of long DNA chains. In the case of short chains it
is necessary to consider not only the breaking of the hydrogen bonds between
single base pairs, but also the complete dissociation of the two strands
forming the double helix.


title: Mirror symmetry on K3 surfaces as a hyperkaehler rotation

abstract:
  We show that under the hypotheses of Strominger, Yau and Zaslow's paper, a
mirror partner of a K3 surface $X$ with a fibration in special Lagrangian tori
can be obtained by rotating the complex structure of $X$ within its
hyperk\"ahler family of complex structures. The same hypotheses force the
B-field to vanish.


title: Quasi-exactly solvable problems and the dual (q-)Hahn polynomials

abstract:
  A second-order differential (q-difference) eigenvalue equation is constructed
whose solutions are generating functions of the dual (q-)Hahn polynomials. The
fact is noticed that these generating functions are reduced to the (little
q-)Jacobi polynomials, and implications of this for quasi-exactly solvable
problems are studied. A connection with the Azbel-Hofstadter problem is
indicated.


title: Contact geometry in Lagrangean mechanics

abstract:
  We present a picture of Lagrangean mechanics, free of some unnatural features
(such as complete divergences). As a byproduct, a completely natural
U(1)-bundle over the phase space appears. The correspondence between classical
and quantum mechanics is very clear, e.g. no topological ambiguities remain.
Contact geometry is the basic tool.


title:
Radiation Reaction fields for an accelerated dipole for scalar and
  electromagnetic radiation

abstract:
  The radiation reaction fields are calculated for an accelerated changing
dipole in scalar and electromagnetic radiation fields. The acceleration
reaction is shown to alter the damping of a time varying dipole in the EM case,
but not the scalar case. In the EM case, the dipole radiation reaction field
can exert a force on an accelerated monopole charge associated with the
accelerated dipole. The radiation reaction of an accelerated charge does not
exert a torque on an accelerated magnetic dipole, but an accelerated dipole
does exert a force on the charge. The technique used is that originally
developed by Penrose for non-singular fields and extended by the author for an
accelerated monopole charge.


title: Differing Interactions Require Baryon and Lepton Conservation

abstract:
  Baryon and lepton numbers are conserved. Why? Baryon number must be because
baryons are subject to strong interactions, leptons are not. Conservation of
baryons leads to that of leptons. This raises further questions which are
noted.


title: Nonlinear Debye-Onsager-Relaxation-Effect

abstract:
  The quantum kinetic equation for charged particles in strong electric fields
is used to derive the nonlinear particle flux. The relaxation field is
calculated quantum mechanically up to any order in the applied field provided a
given Maxwellian plasma. The classical limit is given in analytical form. In
the range of weak fields the deformation of the screening cloud is responsible
for the Debye-Onsager relaxation effect.


title: Formation of correlations in strongly coupled plasmas

abstract:
  The formation of binary correlations in plasma is studied from the quantum
kinetic equation. It is shown that this formation is much faster than
dissipation due to collisions. In a hot (dense) plasma the correlations are
formed on the scale of inverse plasma frequency (Fermi energy). We derive
analytical formulae for the time dependency of the potential energy which
measures the extent of correlations. We discuss the dynamical formation of
screening and compare with the statical screened result. Comparisons are made
with molecular dynamic simulations.


title: Transport theory with nonlocal corrections

abstract:
  A kinetic equation which combines the quasiparticle drift of Landau's
equation with a dissipation governed by a nonlocal and noninstant scattering
integral in the spirit of Snider's equation for gases is derived. Consequent
balance equations for the density, momentum and energy include quasiparticle
contributions and the second order quantum virial corrections and are proven to
be consistent with conservation laws.


title: Medium modification of two-particle scattering in nonideal Bose systems

abstract:
  Medium modification of scattering properties in interacting Bose systems are
considered by solving the Bethe-Salpeter equation. An equation of state for the
normal phase (generalized Beth-Uhlenbeck formula) is given using the in-medium
phase shifts to include two-particle correlations. Conclusions are drawn for
systems of bosonic atoms with repulsive interaction such as sodium $^{23}$Na
and rubidium $^{87}$Rb. It is shown that the in-medium scattering length and
the absolute value of the in-medium scattering phase shift for low scattering
energies increase with density.

categories: physics.atom-ph cond-mat.stat-mech nucl-th physics.acc-ph


title: Anomalous scaling behavior in Takens-Bogdanov bifurcations

abstract:
  A general algorithm is presented for estimating the nonlinear instability
threshold, $\sigma_c$, for subcritical transitions in systems where the
linearized dynamics is significantly non-normal (i.e. subcritical bifurcations
of {\em Takens-Bogdanov} type). The $N$-dimensional degenerate node is
presented as an example. The predictions are then compared to numerical studies
with excellent agreement.

categories: physics.class-ph math-ph math.MP nlin.CD


title: Long-range interactions of metastable helium atoms

abstract:
  Polarizabilities, dispersion coefficients, and long-range atom-surface
interaction potentials are calculated for the n=2 triplet and singlet states of
helium using highly accurate, variationally determined, wave functions.