title:
A Parallel Tree code for large Nbody simulation: dynamic load balance
  and data distribution on CRAY T3D system

abstract:
  N-body algorithms for long-range unscreened interactions like gravity belong
to a class of highly irregular problems whose optimal solution is a challenging
task for present-day massively parallel computers. In this paper we describe a
strategy for optimal memory and work distribution which we have applied to our
parallel implementation of the Barnes & Hut (1986) recursive tree scheme on a
Cray T3D using the CRAFT programming environment. We have performed a series of
tests to find an " optimal data distribution " in the T3D memory, and to
identify a strategy for the " Dynamic Load Balance " in order to obtain good
performances when running large simulations (more than 10 million particles).
The results of tests show that the step duration depends on two main factors:
the data locality and the T3D network contention. Increasing data locality we
are able to minimize the step duration if the closest bodies (direct
interaction) tend to be located in the same PE local memory (contiguous block
subdivison, high granularity), whereas the tree properties have a fine grain
distribution. In a very large simulation, due to network contention, an
unbalanced load arises. To remedy this we have devised an automatic work
redistribution mechanism which provided a good Dynamic Load Balance at the
price of an insignificant overhead.


title:
The Analytical Solution of Radiation Transfer Equation for a Layer of
  Magnetized Plasma With Random Irregularities

abstract:
  The problem of radio wave reflection from an optically thick plane monotonous
layer of magnetized plasma is considered at present work. The plasma electron
density irregularities are described by spatial spectrum of an arbitrary form.
The small-angle scattering approximation in the invariant ray coordinates is
suggested for analytical investigation of the radiation transfer equation. The
approximated solution describing spatial-and-angular distribution of radiation
reflected from a plasma layer is obtained. The obtained solution can be
applied, for example, to the ionospheric radio wave propagation.


title: Adiabatic passage by light-induced potentials in molecules

abstract:
  We present the APLIP process (Adiabatic Passage by Light Induced Potentials)
for the adiabatic transfer of a wave packet from one molecular potential to the
displaced ground vibrational state of another. The process uses an intermediate
state, which is only slightly populated, and a counterintuitive sequence of
light pulses to couple the three molecular states. APLIP shares many features
with STIRAP (stimulated Raman adiabatic passage), such as high efficiency and
insensitivity to pulse parameters. However, in APLIP there is no two-photon
resonance, and the main mechanism for the transport of the wave packet is a
light-induced potential. The APLIP process appears to violate the Franck-Condon
principle, because of the displacement of the wave packet, but does in fact
take place on timescales which are at least a little longer than a vibrational
timescale.


title: Lorentz Symmetry Violation, Vacuum and Superluminal Particles

abstract:
  If textbook Lorentz invariance is actually a property of the equations
describing a sector of the excitations of vacuum above some critical distance
scale, several sectors of matter with different critical speeds in vacuum can
coexist and an absolute rest frame (the vacuum rest frame) may exist without
contradicting the apparent Lorentz invariance felt by "ordinary" particles
(particles with critical speed in vacuum equal to $c$, the speed of light).
Sectorial Lorentz invariance, reflected by the fact that all particles of a
given dynamical sector have the same critical speed in vacuum, will then be an
expression of a fundamental sectorial symmetry (e.g. preonic grand unification
or extended supersymmetry) protecting a parameter of the equations of motion.
Furthermore, the sectorial Lorentz symmetry may be only a low-energy limit, in
the same way as the relation $\omega $ (frequency) = $c_s$ (speed of sound) $k$
(wave vector) holds for low-energy phonons in a crystal. We show that, in this
context, phenomena such as the absence of Greisen-Zatsepin-Kuzmin cutoff and
the stability of unstable particles at very high energy are basic properties of
a wide class of noncausal models where local Lorentz invariance is broken
introducing a fundamental length. Then, observable phenomena are produced at
the wavelength scale of the highest-energy cosmic rays or even below this
energy, but Lorentz symmetry violation remains invisible to standard low-energy
tests. We discuss possible theoretical, phenomenological, experimental and
cosmological implications of this new approach to matter and space-time, as
well as prospects for future developments.


title:
Negative-energy perturbations in cylindrical equilibria with a radial
  electric field

abstract:
  The impact of an equilibrium radial electric field $E $ on negative-energy
perturbations (NEPs) (which are potentially dangerous because they can lead to
either linear or nonlinear explosive instabilities) in cylindrical equilibria
of magnetically confined plasmas is investigated within the framework of
Maxwell-drift kinetic theory. It turns out that for wave vectors with a
non-vanishing component parallel to the magnetic field the conditions for the
existence of NEPs in equilibria with E=0 [G. N. Throumoulopoulos and D.
Pfirsch, Phys. Rev. E 53, 2767 (1996)] remain valid, while the condition for
the existence of perpendicular NEPs, which are found to be the most important
perturbations, is modified. For $|e_i\phi|\approx T_i$ ($\phi$ is the
electrostatic potential) and $T_i/T_e > \beta_c\approx P/(B^2/8\pi)$ ($P$ is
the total plasma pressure), a case which is of operational interest in magnetic
confinement systems, the existence of perpendicular NEPs depends on $e_\nu E$,
where $e_\nu$ is the charge of the particle species $\nu$. In this case the
electric field can reduce the NEPs activity in the edge region of tokamaklike
and stellaratorlike equilibria with identical parabolic pressure profiles, the
reduction of electron NEPs being more pronounced than that of ion NEPs.


title: Linear Nijenhuis-Tensors and the Construction of Integrable Systems

abstract:
  A new method to construct Hamiltonian functions in involution is presented.
We show that on left-symmetric algebras a Nijenhuis-tensor is given in a
natural manner by the usual right-multiplication. Furthermore we prove that
symplectic Lie-algebras carry the structure of a Poisson-Nijenhuis manifold.


title: A New Family of Solvable Self-Dual Lie Algebras

abstract:
  A family of solvable self-dual Lie algebras is presented. There exist a few
methods for the construction of non-reductive self-dual Lie algebras: an
orthogonal direct product, a double-extension of an Abelian algebra, and a
Wigner contraction. It is shown that the presented algebras cannot be obtained
by these methods.


title: On doubly excited states in negative ions

abstract:
  Atomic negative ions are fragile quantum systems in which correlation among
the valence electrons plays a very important role. For doubly excited states
correlation becomes dominant. Photodetachment is the process where a negative
ion absorbs a photon and as a consquence ejects the outermost electron. A new
detection scheme has been developed. The residual atom of a photodetachment is
state selectively ionised by resonance ionisation spectroscopy. Investigations
of the photodetachment threshold of tellurium with neutral particle detection
yielded an electron affinity of 1589618(5) m^-1. With state selective detection
the Li(2p) photodetachment threshold was investigated and the electron affinity
was determined to be 498490(17) m^-1. Resonance structure in the Li^-
photodetachment cross section near the Li(3p) threshold has been investigated.
According to an assisting calculation this structure is analogous to the
symmetrically excited intrashell (_3{0}_3^+)^1P^o state in H^-. In He^- the
three doubly excited states, 1s3s4s ^4S, 1s3p^2 ^4P and 1s3p4p ^4P were
investigated. The energy positions of all these resonances [1s3s4s ^4S:
E_0=(2386803.1+-4.2) m^-1, Gamma=160(16) m^-1; 1s3p^2 ^4P: E_0=2.4782(55)x10^6
m^-1, Gamma=40(3)x10^3 m^-1; 1s3p4p ^4P: E_0=2633297(40) m^-1, Gamma=492(35)
m^-1] agree with a recent calculation. The width of the 1s3s4s ^4S resonance
agrees with this calculation, but for the 1s3p^2 ^4P resonance there is a
slight discrepancy and the 1s3p4p ^4P resonance is only half as broad as
predicted.


title: Quantum Harmonic Analysis and Geometric Invariants

abstract:
  We develop from scratch a theory of invariants within the framework of
non-commutative geometry. Given an operator Q (a supercharge in physics
language) and an operator a (whose square equals the identity I), we derive a
general formula for an invariant Z(Q,a) depending on Q and a. In case a=I, our
formula reduces to the McKean-Singer representation of the index of Q. The
function Z is invariant in the following sense: if Q=Q(s) depends on a
parameter s, and if Z(Q(s),a) is differentiable in s, then in fact Z(Q(s),a) is
independent of s. We give detailed conditions on Q(s) for which Z(Q(s),a) is
differentiable in s. At the end of this paper, we consider a 2-dimensional
generalization of our theory motivated by space-time supersymmetry. In the case
that expectations are given by functional integrals, Z(Q,a) has a simple
integral representation. We also explain in detail how our construction relates
to Connes' entire cyclic cohomology, as well as to other frameworks.


title: Alternative method of generation of Cerenkov radiation or shock wave

abstract:
  An alternative method of generation of Cerenkev radiation is proposed over
here with the help of a rotating source and a reflector. The principle is that,
if we focus a narrow beam of light on to source of light is rotated with
certain angular velocity then the light spot on the surface will move with very
high velocity which may exceed the velocity of light. As a consequence of this
we shall observe an effect very similar to Cerknov radiation.


title: The NSNS High Energy Beam Transport Line

abstract:
  In the National Spallation Neutron Source (NSNS) design, a 180 meter long
transport line connects the 1 GeV linac to an accumulator ring. The linac beam
has a current of 28 mA, pulse length of 1 ms, and 60 Hz rep rate. The high
energy transport line consists of sixteen 60 degrees FODO cells, and
accommodates a 90 degrees achromatic bend, an energy compressor, collimators,
part of injection system, and enough diagnostic devices to measure the beam
quality before injection. To reduce the uncontrolled beam losses, this line has
nine beam halo scrapers and very tight tolerances on both transverse and
longitudinal beam dynamics under space charge conditions. The design of this
line is presented.


abstract:
  Projections of charged particle beam current density (profiles) are
frequently used as a measure of beam position and size. In conventional
practice only two projections, usually horizontal and vertical, are measured.
This puts a severe limit on the detail of information that can be achieved. A
third projection provides a significant improvement. The Algebraic
Reconstruction Technique (ART) uses three or more projections to reconstruct
3-dimensional density profiles. At the 200 MeV H- linac, we have used this
technique to measure beam density, and it has proved very helpful, especially
in helping determine if there is any coupling present in x-y phase space. We
will present examples of measurements of current densities using this
technique.


title:
Facilitated alkali ion transfer at the water 1,2-dichloroethane
  interphase: Ab-initio calculations concerning alkaline metal cation -
  1,10-phenanthroline complexes

abstract:
  A series of calculations on the energetics of complexation of alkaline metals
with 1,10-phenanthroline are presented. It is an experimental fact that the
ordering of the free energy of transfer across the water - 1,2-dichloroethane
interphase is governed by the charge / size ratio of the diferent cations; the
larger cations showing the lower free energy of transfer. This ordering of the
free energies of transfer is reverted in the presence of 1,10-phenanthroline in
the organic phase. We have devised a thermodynamic cycle for the transfer
process and by means of ab-initio calculations have drawn the conclusion that
in the presence of phen the free energy of transfer is governed by the
stability of the PHEN/M $^{+}$complex, which explains the observed tendency
from a theoretical point of view.


title:
The Method of Geodesic Expansions and its Application to the
  Semiclassical Sum over Immersed Manifolds

abstract:
  The method of geodesic expansions is systematically explained. Based on the
Haar measures of the group of geodesic expansions the semiclassical sum over
immersed manifolds is constructed. Gauge fixing is performed via the Faddeev
Popov method.


title: What was the fastest 100m final?

abstract:
  In a previous article (physics/9705004), the best 100m performances in track
and field were determined by accounting for wind effects and atmospheric drag.
In this report, I seek to ascertain what was the "fastest" 100m final through a
statistical analysis of the competitors' times. Considered are the 100 finals
from the 1984-1996 Olympic Games, the 1983-1997 World Championships, and the
1996 Grand Prix Final from Lausanne, SWI, in which Frank Fredericks (Namibia)
recorded the only sub-9.90s time ever into a head-wind (9.86s, -0.4 m/s).


title: Dielectric function of nonideal plasmas and electrical dc conductivity

abstract:
  Within generalized linear response theory, an expression for the dielectric
function is derived which is consistent with standard approaches to the
electrical dc conductivity. Explicit results are given for the first moment
Born approximation. Some exact relations as well as the limiting behaviour at
small values of the wave number and frequency are investigated.


title: One-particle spectral function of electrons in a hot and dense plasma

abstract:
  A self-consistent determination of the spectral function and the self-energy
of electrons in a hot and dense plasma is reported. The self-energy is
determined within the approximation of the screened potential. It is shown,
that the quasi-particle concept is not an adequate concept for hot and dense
plasmas, since the width of the spectral function has to be considered. As an
example, the solar core plasma is discussed. An effective quasi-particle
picture is introduced and results for the solar core plasma as well as for ICF
plasmas are presented.


title: Another Dash into the Record Books (wind: -2.1 m/s)

abstract:
  In the wake of numerous injuries and Donovan Bailey's media-stamped "sub-par"
100m victory of 10.03s at the 1997 Canadian Track and Field Championships, a
medal hope at the 1997 World Championships seems grim for the Olympic Champion
and World Record holder. However, when one considers that the 10.03s was run
into a hefty head-wind (-2.1 m/s), a simple correction for this effect can help
to restore Canada's faith in their sprint hero -- not to mention rewrite the
record books again.


title: Dielectric function of a two-component plasma including collisions

abstract:
  A multiple-moment approach to the dielectric function of a dense non-ideal
plasma is treated beyond RPA including collisions in Born approximation. The
results are compared with the perturbation expansion of the Kubo formula. Sum
rules as well as Ward identities are considered. The relations to optical
properties as well as to the dc electrical conductivity are pointed out.


title:
Nonlinear axisymmetric resistive magnetohydrodynamic equilibria with
  toroidal flow

abstract:
  The equilibrium of a resistive axisymmetric plasma with purely toroidal flow
surrounded by a conductor is investigated within the framework of the nonlinear
magnetohydrodynamic theory. It is proved that a) the poloidal current density
vanishes and b) apart from an idealized case the pressure profile should vanish
on the plasma boundary. For the cases of isothermal magnetic surfaces,
isentropic magnetic surfaces and magnetic surfaces with constant density, the
equilibrium states obey to an elliptic partial differential equation for the
poloidal magnetic flux function, which is identical in form to the
corresponding equation governing ideal equilibria. The conductivity, which can
not be either uniform or a surface quantity, results however in a restriction
of the possible classes of equilibrium solutions, e.g., for the cases
considered the only possible equilibria with Spitzer conductivity are of
cylindrical shape.


title: Monte Carlo Simulation of Comptonization in Inhomogeneous Media

abstract:
  Comptonization is the process in which photon spectrum changes due to
multiple Compton scatterings in the electronic plasma. It plays an important
role in the spectral formation of astrophysical X-ray and gamma-ray sources.
There are several intrinsic limitations for the analytical method in dealing
with the Comptonization problem and Monte Carlo simulation is one of the few
alternatives. We describe an efficient Monte Carlo method that can solve the
Comptonization problem in a fully relativistic way. We expanded the method so
that it is capable of simulating Comptonization in the media where electron
density and temperature varies discontinuously from one region to the other and
in the isothermal media where density varies continuously along photon paths.
The algorithms are presented in detail to facilitate computer code
implementation. We also present a few examples of its application to the
astrophysical research.


title: Parallel computing and molecular dynamics of biological membranes

abstract:
  In this talk I discuss the general question of the portability of Molecular
Dynamics codes for diffusive systems on parallel computers of the APE family.
The intrinsic single precision arithmetics of the today available APE platforms
does not seem to affect the numerical accuracy of the simulations, while the
absence of integer addressing from CPU to individual nodes puts strong
constraints on the possible programming strategies. Liquids can be very
satisfactorily simulated using the "systolic" method. For more complex systems,
like the biological ones at which we are ultimately interested in, the "domain
decomposition" approach is best suited to beat the quadratic growth of the
inter-molecular computational time with the number of elementary components of
the system. The promising perspectives of using this strategy for extensive
simulations of lipid bilayers are briefly reviewed.

categories: physics.bio-ph cond-mat.soft hep-lat q-bio


title: Some models of spin coherence and decoherence in storage rings

abstract:
  I present some simple exactly solvable models of spin diffusion caused by
synchrotron radiation noise in storage rings. I am able to use standard
stochastic differential equation and Fokker-Planck methods and I thereby
introduce, and exploit, the polarization density. This quantity obeys a linear
evolution equation of the Bloch type, which is, like the Fokker-Planck
equation, universal in the sense that it is independent of the state of the
system. I also briefly consider Bloch equations for other local polarization
quantities derived from the polarization density. One of the models chosen is
of relevance for some existing and proposed low energy electron (positron)
storage rings which need polarization. I present numerical results for a ring
with parameters typical of HERA and show that, where applicable, the results of
my approach are in satisfactory agreement with calculations using SLIM. These
calculations provide a numerical check of a basic tenet of the conventional
method of calculating depolarization using the n-axis. I also investigate the
equilibrium behaviour of the spin ensemble when there is no synchrotron
radiation. Finally, I summarize other results which I have obtained using the
polarization density and which will be published separately.


title: Improved Algorithms for Simulating Crystalline Membranes

abstract:
  The physics of crystalline membranes, i.e. fixed-connectivity surfaces
embedded in three dimensions and with an extrinsic curvature term, is very rich
and of great theoretical interest. To understand their behavior, numerical
simulations are commonly used. Unfortunately, traditional Monte Carlo
algorithms suffer from very long auto-correlations and critical slowing down in
the more interesting phases of the model. In this paper we study the
performance of improved Monte Carlo algorithms for simulating crystalline
membrane, such as hybrid overrelaxation and unigrid methods, and compare their
performance to the more traditional Metropolis algorithm. We find that although
the overrelaxation algorithm does not reduce the critical slowing down, it
gives an overall gain of a factor 15 over the Metropolis algorithm. The unigrid
algorithm does, on the other hand, reduce the critical slowing down exponent to
z apprx. 1.7.


title:
The GRAAL high resolution BGO calorimeter and its energy calibration and
  monitoring system

abstract:
  We describe the electromagnetic calorimeter built for the GRAAL apparatus at
the ESRF. Its monitoring system is presented in detail. Results from tests and
the performance obtained during the first GRAAL experiments are given. The
energy calibration accuracy and stability reached is a small fraction of the
intrinsic detector resolution.


title: X-ray emission during the muonic cascade in hydrogen

abstract:
  We report our investigations of X rays emitted during the muonic cascade in
hydrogen employing charge coupled devices as X-ray detectors. The density
dependence of the relative X-ray yields for the muonic hydrogen lines (K_alpha,
K_beta, K_gamma) has been measured at densities between 0.00115 and 0.97 of
liquid hydrogen density. In this density region collisional processes dominate
the cascade down to low energy levels. A comparison with recent calculations is
given in order to demonstrate the influence of Coulomb deexcitation.


title: Excited State Muon Transfer in Hydrogen/Deuterium Mixtures

abstract:
  We report the first direct observation of excited state muon transfer in
hydrogen/deuterium mixtures by direct measurement of q_1s, the probability that
a mu-p atom, which is initially formed in an excited state, reaches the 1s
ground state. The dependence of q_1s on deuterium concentration c_d was
measured for two different densities at cryogenic temperatures using charge
coupled devices (CCDs) to detect the muonic X rays. First results based on the
analysis of the K_alpha-lines of the two isotopes are presented.


title: Heating-Assisted Atom Transfer in the Scanning Tunneling Microscope

abstract:
  The effects of a voltage pulse on the localization probability for a Xe atom
prepared in a pure state localized on the STM surface at 0 temperature is
investigated by numerically integrating the time-dependent Schroedinger
equation. In these calculations the environmental interactions are neglected,
and voltage pulses of 20 and 7 ns with symmetric triangular and trapezoidal
shapes are considered. The atom dynamics at an environmental temperature of 4 K
is studied in the frame of a stochastic, non-linear Liouville equation for the
density operator. It is shown that the irreversible transfer from surface to
tip may be explained by thermal decoherence rather than by the driving force
acting during the application of the voltage pulse.


title: Asymptotic conditions of motion for radiating charged particles

abstract:
  Approximate asymptotic conditions on the motion of compact, electrically
charged particles are derived within the framework of general relativity using
the Einstein- Infeld-Hoffmann (EIH) surface integral method. While
superficially similar to the Abraham-Lorentz and Lorentz-Dirac (ALD) equations
of motion, these conditions differ from them in several fundamental ways. They
are not equations of motion in the usual sense but rather a set of conditions
which these motions must obey in the asymptotic future of an initial value
surface. In addition to being asymptotic, these conditions of motion are
approximate and apply, as do the original EIH equations, only to slowly moving
systems. Also, they do not admit the run- away solutions of these other
equations. As in the original EIH work, they are integrability conditions
gotten from integrating the empty-space (i.e., source free) Einstein-Maxwell
equations of general relativity over closed two-surfaces surrounding the
sources of the fields governed by these equations. No additional ad hoc
assumptions, such as the form of a force law or the introduction of inertial
reaction terms, needed to derive the ALD equations are required for this
purpose. Nor is there a need for any of the infinite mass renormalizations that
are required in deriving these other equations.


title: Structure and Bonding in Small Neutral Alkali-Halide Clusters

abstract:
  The structural and bonding properties of small neutral alkali-halide clusters
(AX)n, with n less than or equal to 10, A=Li, Na, K, Rb and X=F, Cl, Br, I, are
studied using the ab initio Perturbed Ion (aiPI) model and a restricted
structural relaxation criterion. A trend of competition between rock-salt and
hexagonal ring-like isomers is found and discussed in terms of the relative
ionic sizes. The main conclusion is that an approximate value of r_C/r_A=0.5
(where r_C and r_A are the cationic and anionic radii) separates the hexagonal
from the rock-salt structures. The classical electrostatic part of the total
energy at the equilibrium geometry is enough to explain these trends. The magic
numbers in the size range studied are n= 4, 6 and 9, and these are universal
since they occur for all alkali-halides and do not depend on the specific
ground state geometry. Instead those numbers allow for the formation of compact
clusters. Full geometrical relaxations are considered for (LiF)n (n=3-7) and
(AX)_3 clusters, and the effect of Coulomb correlation is studied in a few
selected cases. These two effects preserve the general conclusions achieved
thus far.


title: Eigenvalues of Casimir operators for $gl(m/\infty)$

abstract:
  A full set of Casimir operators for the Lie superalgebra $gl(m/\infty)$ is
constructed and shown to be well defined in the category $O_{FS}$ generated by
the highest weight irreducible representations with only a finite number of
non-zero weight components. The eigenvalues of these Casimir operators are
determined explicitly in terms of the highest weight. Characteristic identities
satisfied by certain (infinite) matrices with entries from $gl(m/\infty)$ are
also determined.


title: Radiation Induced Damage in GaAs Particle Detectors

abstract:
  The motivation for investigating the use of GaAs as a material for detecting
particles in experiments for High Energy Physics (HEP) arose from its perceived
resistance to radiation damage. This is a vital requirement for detector
materials that are to be used in experiments at future accelerators where the
radiation environments would exclude all but the most radiation resistant of
detector types.


title: Preliminary Results for LP VPE X-Ray Detectors

abstract:
  Thick epitaxial layers have been grown using Low Pressure Vapour Phase
Epitaxy techniques with low free carrier concentrations . This type of material
is attractive as a medium for X-ray detection, because of its high conversion
efficiency for X-rays in the medically interesting energy range.


title: Excitons with anisotropic effective mass

abstract:
  We present a simple analytic scheme for calculating the binding energy of
excitons in semiconductors that takes full account of the existing anisotropy
in the effective mass, as a complement to the qualitative treatment in most
textbooks. Results obtained for excitons in gallium nitride form the basis for
a discussion of the accuracy of this approach.


title: Bound States and Scattering Processes in the ^4He_3 Atomic System

abstract:
  We present a mathematically rigorous method for solving three-atomic bound
state and scattering problems. The method is well suited for applications in
systems where the inter-atomic interaction is of a hard-core nature. It has
been employed to obtain the ground- and excited-state energies for the Helium
trimer and to calculate, for the first time, the scattering phase shifts and
wave-functions for the He atom-He dimer at ultra-low energies.


title: Subatomic Physics-100 Not Out and Still Going Strong!

abstract:
  On the occasion of the birth centenary of the discovery of electron, I
discuss its role in the area of Elementary Particle Physics. I emphasize that
the discovery of electron marks the end of the speculation era lasting more
than 2500 years. The key developments leading to the discovery of electron by
J.J. Thomson are mentioned. The standard model is briefly described. It is
emphasized that this model is unsatisfactory in several respects, however no
further progress beyond standard model is possible unless there is a dramatic
advance in instrumentation.


title: The Hilbert-Schmidt Theorem Formulation of the R-Matrix Theory

abstract:
  Using the Hilbert-Schmidt theorem, we reformulate the R-matrix theory in
terms of a uniformly and absolutely convergent expansion. Term by term
differentiation is possible with this expansion in the neighborhood of the
surface. Methods for improving the convergence are discussed when the
R-function series is truncated for practical applications.


title:
Spontaneous emission spectrum of the non-lasing supermodes in
  semiconductor laser arrays

abstract:
  It is shown that the interference between spontaneous emission into the
non-lasing supermode and the laser field of a semiconductor laser array causes
spatial holeburning which couples the dynamics of the spontaneous emission with
the laser field. In particular, phase locking between the spontaneous emission
and the lasing mode leads to the formation of a spectral triplet composed of
in-phase relaxation oscillation sidebands and an out-of-phase line at the
lasing frequency.

categories: physics.optics adap-org nlin.AO quant-ph


title:
AC-coupled GaAs microstrip detectors with a new type of integrated bias
  resistors

abstract:
  Full size single-sided GaAs microstrip detectors with integrated coupling
capacitors and bias resistors have been fabricated on 3'' substrate wafers.
PECVD deposited SiO_2 and SiO_2/Si_3N_4 layers were used to provide coupling
capacitaces of 32.5 pF/cm and 61.6 pF/cm, respectively. The resistors are made
of sputtered CERMET using simple lift of technique. The sheet resistivity of 78
kOhm/sq. and the thermal coefficient of resistance of less than 4x10^-3 /
degree C satisfy the demands of small area biasing resistors, working on a wide
temperature range.


title: Ion Sizes and Finite-Size Corrections for Ionic-Solvation Free Energies

abstract:
  Free energies of ionic solvation calculated from computer simulations exhibit
a strong system size dependence. We perform a finite-size analysis based on a
dielectric-continuum model with periodic boundary conditions. That analysis
results in an estimate of the Born ion size. Remarkably, the finite-size
correction applies to systems with only eight water molecules hydrating a
sodium ion and results in an estimate of the Born radius of sodium that agrees
with the experimental value.


title:
Do Quasi-Exactly Solvable Systems Always Correspond to Orthogonal
  Polynomials?

abstract:
  We consider two quasi-exactly solvable problems in one dimension for which
the Schr\"odinger equation can be converted to Heun's equation. We show that in
neither case the Bender-Dunne polynomials form an orthogonal set. Using the
anti-isopectral transformation we also discover a new quasi-exactly solvable
problem and show that even in this case the polynomials do not form an
orthogonal set.


title: Z_n^3-graded Poincare superalgebras

abstract:
  Using colored superanalysis and epsilon-Lie superalgebras, we build the
minimal Poincare superalgebra in the case of the Z_n^3-grading. We then build a
representation of this algebra, and the corresponding Poincare supergroup.


title: An Introduction to Noncommutative Geometry

abstract:
  This is the introduction and bibliography for lecture notes of a course given
at the Summer School on Noncommutative Geometry and Applications, sponsored by
the European Mathematical Society, at Monsaraz and Lisboa, Portugal, September
1-10, 1997. In the published version, an epilogue of recent developments and
many new references from 1998-2006 have been added.
  1. Commutative geometry from the noncommutative point of view.
  2. Spectral triples on the Riemann sphere.
  3. Real spectral triples, the axiomatic foundation.
  4. Geometries on the noncommutative torus.
  5. The noncommutative integral.
  6. Quantization and the tangent groupoid.
  7. Equivalence of geometries.
  8. Action functionals.
  9. Epilogue: new directions.


title: The local structure of n-Poisson and n-Jacobi manifolds

abstract:
  N-Lie algebra structures on smooth function algebras given by means of
multi-differential operators, are studied. Necessary and sufficient conditions
for the sum and the wedge product of two $n$-Poisson sructures to be again a
multi-Poisson are found. It is proven that the canonical $n$-vector on the dual
of an n-Lie algebra g is n-Poisson iff dim(g) are not greater than n+1. The
problem of compatibility of two n-Lie algebra structures is analyzed and the
compatibility relations connecting hereditary structures of a given n-Lie
algebra are obtained. (n+1)-dimensional n-Lie algebras are classified and their
"elementary particle-like" structure is discovered. Some simple applications to
dynamics are discussed.


title: Farewell to General Relativity

abstract:
  The kinematical successes of general relativity are legendary: the perihelion
precession, the gravitational red-shift, the bending of light. However, at the
level of dynamics, relativity is faced with insurmountable difficulties. It has
failed to define the energy, momentum, and stress of the gravitational field.
Moreover, it offers no expression of energy-momentum transfer to or from the
gravitational field. These are symptoms of a far graver malady: general
relativity violates the principle of energy conservation.


title: Quantization on a Lie group: Higher-order Polarizations

abstract:
  Contents
  * Introduction
  -- Why $S^1$-extended phase space?
  -- Why central extensions of classical symmetries?
  * Central extension \Gt of a group $G$
  -- Group cohomology
  -- Cohomology and contractions: Pseudo-cohomology
  -- Principal bundle with connection $(\Gtm,\Theta)$
  * Group Approach to Quantization
  -- $U(1)$-quantization
  -- Non-horizontal polarizations
  * Simple examples
  -- The abelian group $R^{k}$
  -- The semisimple group $SU(2)$
  * Algebraic anomalies
  -- Higher-order polarizations
  -- The Schr\"odinger group and Quantum Optics
  -- The Virasoro group and String Theory


title: It's a Wrap! Reviewing the 1997 Outdoor Season

abstract:
  The 100m world rankings of the 1997 outdoor track and field competition
season are reviewed, subject to corrections for wind effects and atmospheric
drag. The rankings and times are compared with those of 1996, and the
improvements of each athlete over the course of a year are discussed.
Additionally, the athletes' wind-corrected 50m and 60m splits from the 1997
IAAF World Championships are compared to the 1997 indoor world rankings over
the same distances, as an attempt to predict possible performances for the
coming 1998 indoor season.


title:
Symmetry analysis of the 1+1 dimensional relativistic imperfect fluid
  dynamics

abstract:
  The flow of the relativistic imperfect fluid in two dimensions is discussed.
We calculate the symmetry group of the energy-momentum tensor conservation
equation in the ultrarelativistic limit. Group-invariant solutions for the
incompressible fluid are obtained


title: Moebius Transformations in Noncommutative Conformal Geometry

abstract:
  We study the projective linear group PGL_2(A), associated with an arbitrary
algebra A, and its subgroups from the point of view of their action on the
space of involutions in A. This action formally resembles Moebius
transformations known from complex geometry. By specifying A to be an algebra
of bounded operators in a Hilbert space H, we rediscover the Moebius group
defined by Connes and study its action on the space of Fredholm modules over
the algebra A. There is an induced action on the K-homology of A, which turns
out to be trivial. Moreover, this action leads naturally to a simpler object,
the polarized module underlying a given Fredholm module, and we discuss this
relation in detail. Any polarized module can be lifted to a Fredholm module,
and the set of different lifts forms a category, whose morphisms are given by
generalized Moebius tranformations. We present an example of a polarized module
canonically associated with the differentiable structure of a smooth manifold
V. Using our lifting procedure we obtain a class of Fredholm modules
characterizing the conformal structures on V. Fredholm modules obtained in this
way are a special case of those constructed by Connes, Sullivan and Teleman.


title: Some Properties of Riesz Means and Spectral Expansions

abstract:
  It is well known that short-time expansions of heat kernels correlate to
formal high-frequency expansions of spectral densities. It is also well known
that the latter expansions are generally not literally true beyond the first
term. However, the terms in the heat-kernel expansion correspond rigorously to
quantities called Riesz means of the spectral expansion, which damp out
oscillations in the spectral density at high frequencies by dint of performing
an average over the density at all lower frequencies. In general, a change of
variables leads to new Riesz means that contain different information from the
old ones. In particular, for the standard second-order elliptic operators,
Riesz means with respect to the square root of the spectral parameter
correspond to terms in the asymptotics of elliptic and hyperbolic Green
functions associated with the operator, and these quantities contain "nonlocal"
information not contained in the usual Riesz means and their correlates in the
heat kernel. Here the relationship between these two sets of Riesz means is
worked out in detail; this involves just classical one-dimensional analysis and
calculation, with no substantive input from spectral theory or quantum field
theory. This work provides a general framework for calculations that are often
carried out piecemeal (and without precise understanding of their rigorous
meaning) in the physics literature.


title: Ludwig Boltzmann -- A Pioneer of Modern Physics

abstract:
  In two respects Ludwig Boltzmann was a pioneer of quantum mechanics. First
because in his statistical interpretation of the second law of thermodynamics
he introduced the theory of probability into a fundamental law of physics and
thus broke with the classical prejudice, that fundamental laws have to be
strictly deterministic. Even Max Planck had not been ready to accept
Boltzmann's statistical methods until 1900. With Boltzmann's pioneering work
the probabilistic interpretation of quantum mechanics had already a precedent.
In fact in a paper in 1897 Boltzmann had already suggested to Planck to use his
statistical methods for the treatment of black body radiation. The second
pioneering step towards quantum mechanics was Boltzmann's introduction of
discrete energy levels. Boltzmann used this method already in his 1872 paper on
the H-theorem. One may ask whether Boltzmann considered this procedure only as
a mathematical device or whether he attributed physical significance to it. In
this connection Ostwald reports that when he and Planck tried to convince
Boltzmann of the superiority of purely thermodynamic methods over atomism at
the Halle Conference in 1891 Boltzmann suddenly said: ``I see no reason why
energy shouldn't also be regarded as divided atomically.'' Finally I would like
to mention, that Boltzmann in his lectures on Natural Philosophy in 1903
already anticipated the equal treatment of space coordinates and time
introduced in the theory of special relativity. Furthermore in the lectures by
Boltzmann and his successor Fritz Hasen\"ohrl in Vienna the students learned
already about noneuclidean geometry, so that they could immediately start to
work when Einstein's general theory of relativity had been formulated.


title:
A light-fronts approach to electron-positron pair production in
  ultrarelativistic heavy-ion collisions

abstract:
  We perform a gauge-transformation on the time-dependent Dirac equation
describing the evolution of an electron in a heavy-ion collision to remove the
explicit dependence on the long-range part of the interaction. We solve, in an
ultra-relativistic limit, the gauged-transformed Dirac equation using
light-front variables and a light-fronts representation, obtaining
non-perturbative results for the free pair-creation amplitudes in the collider
frame. Our result reproduces the result of second-order perturbation theory in
the small charge limit while non-perturbative effects arise for realistic
charges of the ions.


title: Electrode thickness measurement of a Si(Li) detector for the SIXA array

abstract:
  Cathode electrodes of the Si(Li) detector elements of the SIXA X-ray
spectrometer array are formed by gold-palladium alloy contact layers. The
equivalent thickness of gold in one element was measured by observing the
characteristic L-shell X-rays of gold excited by monochromatised synchrotron
radiation with photon energies above the L3 absorption edge of gold. The
results obtained at 4 different photon energies below the L2 edge yield an
average value of 22.4(35) nm which is consistent with the earlier result
extracted from detection efficiency measurements.
  PACS: 29.40.Wk; 85.30.De; 07.85.Nc; 95.55.Ka
  Keywords: Si(Li) detectors, X-ray spectrometers, X-ray fluorescence, detector
calibration, gold electrodes, synchrotron radiation


title:
Path Integral Quantization of the Symplectic Leaves of the SU(2)*
  Poisson-Lie Group

abstract:
  The Feynman path integral is used to quantize the symplectic leaves of the
Poisson-Lie group SU(2)*. In this way we obtain the unitary representations of
U_q(su(2)). This is achieved by finding explicit Darboux coordinates and then
using a phase space path integral. I discuss the *-structure of SU(2)* and give
a detailed description of its leaves using various parametrizations and also
compare the results with the path integral quantization of spin.


title: Nonuniqueness and Turbulence

abstract:
  The possibility is considered that turbulence is described by differential
equations for which uniqueness fails maximally, at least in some limit. The
inviscid Burgers equation, in the context of Onsager's suggestion that
turbulence should be described by a negative absolute temperature, is such a
limit. In this picture, the onset of turbulence coincides with the
proliferation of singularities which characterizes the failure of uniqueness.


title:
A symmetry adapted approach to vibrational excitations in atomic
  clusters

abstract:
  An algebraic method especially suited to describe strongly anharmonic
vibrational spectra in molecules may be an appropriate framework to study
vibrational spectra of Na$^+_n$ clusters, where nearly flat potential energy
surfaces and the appearance of close lying isomers have been reported. As an
illustration we describe the model and apply it to the Be$_4$, H$_3^+$, Be$_3$
and Na$_3^+$ clusters.


title: Teaching Newton with anticipation(...)

abstract:
  Care making only clock-specific assertions about elapsed-time, and other
``space-time smart'' strategies from the perspective of a selected inertial
map-frame, open doors to an understanding of anyspeed motion via application of
the metric equation.

categories: physics.ed-ph gr-qc physics.acc-ph physics.class-ph


title: High Energy Photon-Photon Colliders

abstract:
  Using the laser backscattering method at future TeV linear colliders one can
obtain gamma-gamma and electron-gamma colliding beams (photon colliders) with
the energy and luminosity comparable to that in e+e- collisions. Now this
option is included to conceptual designs of linear colliders. This paper (talk
at the conference on nonlinear optics) is a short introduction to this field
with an emphasis on required lasers which can be used both for e -> gamma
conversion and for preparation of electron beams (photoguns, laser cooling),
some interesting nonlinear QED effects in a strong field which apply
restrictions on parameters of photon colliders are discussed.

categories: physics.acc-ph hep-ex hep-ph physics.optics


title:
BAYES-LIN: An object-oriented environment for Bayes linear local
  computation

abstract:
  BAYES-LIN is an extension of the LISP-STAT object-oriented statistical
computing environment, which adds to LISP-STAT some object prototypes
appropriate for carrying out local computation via message-passing between
clique-tree nodes of Bayes linear belief networks. Currently the BAYES-LIN
system represents a rather low-level set of tools for a back-end computational
engine, together with diagnostic graphics for understanding the effects of
adjustments on the moral graph. A GUI front end, allowing interactive
formulation of DAG models could be easily added, but is currently missing from
the system. This document provides a very brief introduction to the system, by
means of a work-through of two example computations, followed by a list of
variables, functions, objects and methods provided by the system.


title: Geodesic flows for the Neumann-Rosochatius systems

abstract:
  The Relationship between the Neumann system and the Jacobi system in
arbitrary dimensions is elucidated from the point of view of constrained
Hamiltonian systems. Dirac brackets for canonical variables of both systems are
derived from the constrained Hamiltonians. The geodesic equations corresponding
to the Rosochatius system are studied as an application of our method. As a
consequence a new class of nonlinear integrable equations is derived along with
their conserved quantities.


title: Multidimensional integration in a heterogeneous network environment

abstract:
  We consider several issues related to the multidimensional integration using
a network of heterogeneous computers. Based on these considerations, we develop
a new general purpose scheme which can significantly reduce the time needed for
evaluation of integrals with CPU intensive integrands. This scheme is a
parallel version of the well-known adaptive Monte Carlo method (the VEGAS
algorithm), and is incorporated into a new integration package which uses the
standard set of message-passing routines in the PVM software system.


title:
Molecular dynamics, Langevin, and hybrid Monte Carlo simulations in
  multicanonical ensemble

abstract:
  We demonstrate that the multicanonical approach is not restricted to Monte
Carlo simulations, but can also be applied to simulation techniques such as
molecular dynamics, Langevin, and hybrid Monte Carlo algorithms. The
effectiveness of the methods are tested with an energy function for the protein
folding problem. Simulations in the multicanonical ensemble by the three
methods are performed for a penta peptide, Met-enkephalin. For each algorithm,
it is shown that from only one simulation run one can not only find the
global-minimum-energy conformation but also obtain probability distributions in
canonical ensemble at any temperature, which allows the calculation of any
thermodynamic quantity as a function of temperature.


title:
Numerical Comparisons of Three Recently Proposed Algorithms in the
  Protein Folding Problem

abstract:
  We compare numerically the effectiveness of three recently proposed
algorithms, multicanonical simulations, simulations in a 1/k-ensemble, and
simulated tempering for the protein folding problem. For this we perform
simulations with high statistics for one of the simplest peptides,
Met-enkephalin. While the performances of all three approaches is much better
than traditional methods, we find that the differences among the three are only
marginal.

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


title:
Variation of the Energy Landscape of a Small Peptide under a Change from
  the ECEPP/2 Force Field to ECEPP/3

abstract:
  The multicanonical ansatz is used to study variations in the energy landscape
of a small peptide, Met-enkephalin, under a change from the ECEPP/2 force field
to ECEPP/3. Local minima with energies up to 5 kcal/mol higher than the global
minima are sampled and classified according to H-bridges and backbone angles.
The distribution and relative weight for various temperatures of the minima are
calculated and compared for the two force fields. We demonstrate that while
there are small differences in the energy landscape our results at relevant
temperatures are robust under changes between ECEPP/2 to ECEPP/3.


title: Propagation of a short laser pulse in a plasma

abstract:
  The propagation of an electromagnetic pulse in a plasma is studied for pulse
durations that are comparable to the plasma period. When the carrier frequency
of the incident pulse is much higher than the plasma frequency, the pulse
propagates without distortion at its group speed. When the carrier frequency is
comparable to the plasma frequency, the pulse is distorted and leaves behind it
an electromagnetic wake.


title:
Fock representations of non-centrally extended super-diffeomorphism
  algebras

abstract:
  A class of Fock representations of non-central extensions of the
super-diffeomorphism algebra in (N+1|M) dimensions is constructed, by
superization of the paper [physics/9705040]. The representations act on
trajectories in (N|M)-dimensional superspace, the extra dimension being the
parameter along the trajectory. The restrictions to various subalgebras are
considered. In particular, the centrally extended superconformal algebra is
obtained by restriction to the contact superalgebra K(1|1). This shows that one
of the basic assumptions in superstring theory (the distinguished nature of the
superconformal algebra) is incorrect.


title: Aftershocks in Coherent-Noise Models

abstract:
  The decay pattern of aftershocks in the so-called 'coherent-noise' models [M.
E. J. Newman and K. Sneppen, Phys. Rev. E54, 6226 (1996)] is studied in detail.
Analytical and numerical results show that the probability to find a large
event at time $t$ after an initial major event decreases as $t^{-\tau}$ for
small $t$, with the exponent $\tau$ ranging from 0 to values well above 1. This
is in contrast to Sneppen und Newman, who stated that the exponent is about 1,
independent of the microscopic details of the simulation. Numerical simulations
of an extended model [C. Wilke, T. Martinetz, Phys. Rev. E56, 7128 (1997)] show
that the power-law is only a generic feature of the original dynamics and does
not necessarily appear in a more general context. Finally, the implications of
the results to the modeling of earthquakes are discussed.

categories: physics.data-an adap-org cond-mat.dis-nn cond-mat.stat-mech nlin.AO


title: The geometry of spacetime with superluminal phenomena

abstract:
  Recent theoretical results show the existence of arbitrary speeds (0 <= v <
\infty) solutions of all relativistic wave equations. Some recent experiments
confirm the results for sound waves. The question arises naturally: What is the
appropriate geometry of spacetime to describe superluminal phenomena? In this
paper we present a spacetime model that incorporates the valid results of
Relativity Theory and yet describes coherently superluminal phenomena without
paradoxes.


title: Launching of Non-Dispersive Superluminal Beams

abstract:
  In this paper we analyze the physical meaning of sub- and superluminal
soliton-like solutions (as the X-waves) of the relativistic wave equations and
of some non-trivial solutions of the free Schr\"odinger equation for which the
concepts of phase and group velocities have a different meaning than in the
case of plane wave solutions. If we accept the strict validity of the principle
of relativity, such solutions describe objects of two essentially different
natures: carrying energy wave packets and inertia-free properly phase
vibrations. Speeds of the first-type objects can exceed the plane wave velocity
$c_*$ only inside media and are always less than the vacuum light speed $c$.
Particularly, very fast sound pulses with speeds $c_* < v < c$ have already
been launched. The second-type objects are incapable of carrying energy and
information but have superluminal speed. If we admit the possibility of a
breakdown of Lorentz invariance, pulses described, for example, by superluminal
solutions of the Maxwell equations can be generated. Only experiment will give
the final answer.


title: Hydrolysis of ferric ion in water and conformational equilibrium

abstract:
  Reported here are results of theoretical calculations on the hexaaquoferric
complex and deprotonated products to investigate the molecular mechanisms of
hydrolysis of ferric ion in water. The combination of density functional
electronic structure techniques and a dielectric continuum model for
electrostatic solvation applied to the Fe(H$_2$O)$_6$$^{3+}$ complex yields
-1020~kcal/mol (experimental values -1037~kcal/mol to -1019~kcal/mol) for the
absolute free energy of the aqueous ferric ion. The predicted reaction energy
change for the first hydrolysis is 2 kcal/mol (compared to 3 kcal/mol
experimental). For the second hydrolysis, we found an unexpected low energy
isomer of Fe(H$_2$O)$_4$(OH)$_2$$^{+}$ with five ligands in the inner sphere
and one water outside. The cis and trans isomers are, respectively, slightly
lower and higher in energy. Extrusion of the additional water to the outer
sphere is nearly thermoneutral. The reaction free energy for the second
hydrolysis is predicted in the range 16-18~kcal/mol, higher than the
experimental value of 5~kcal/mol. Since the theoretical predictions for the
second hydrolysis are higher than experimental values and novel structures were
encountered, we argue that conformational entropy is important in these
reactions.


title: Faster Than Light ?

abstract:
  In this paper we present a pedestrian review of the theoretical fact that all
relativistic wave equations possess solutions of arbitrary velocities $0 \leq v
< \infty$. We discuss some experimental evidences of $v \geq c$ transmission of
electromagnetic field configurations and the importance of these facts with
regard to the principle of relativity.


title: Parallelization of adaptive MC Integrators

abstract:
  Monte Carlo (MC) methods for numerical integration seem to be embarassingly
parallel on first sight. When adaptive schemes are applied in order to enhance
convergence however, the seemingly most natural way of replicating the whole
job on each processor can potentially ruin the adaptive behaviour. Using the
popular VEGAS-Algorithm as an example an economic method of semi-micro
parallelization with variable grain-size is presented and contrasted with
another straightforward approach of macro-parallelization. A portable
implementation of this semi-micro parallelization is used in the xloops-project
and is made publicly available.


title: Simple Linearizations of the Simple Pendulum for Any Amplitude

abstract:
  Two simple, interpolatory-like linearizations are shown for the simple
pendulum which can be used for any initial amplitude.


title:
A unified theory for construction of arbitrary speeds (0 < = v < \infty)
  solutions of the relativistic wave equations

abstract:
  Representing the relativistic physical fields as sections of the Clifford
Bundle (or of the Spin-Clifford Bundle) of Minkowski spacetime we show that all
the relativistic wave equations satisfied by these fields possess solutions
traveling with arbitrary speeds $0 \leq v < \infty$. By giving rigorous
mathematical definitions of reference frames and of the Principle of Relativity
(PR) we prove that physical realizations of the $v > 1$ solutions of, e.g., the
Maxwell equations imply in a breakdown of the PR, but in no contradiction at
all with known physical facts.


title: Infinite Order Discrete Variable Representation for Quantum Scattering

abstract:
  A new approach to multi-dimensional quantum scattering by the infinite order
discrete variable representation is presented. Determining the expansion
coefficients of the wave function at the asymptotic regions by the solution of
the differential Schr\"{o}dinger equation, we reduce an infinite set of linear
equations to a finite one. Application to the benchmark collinear $H + H_2 \to
H_2 + H$ reaction is shown to yield precise reaction probabilities.


title: Coherent States on Lie Algebras: A Constructive Approach

abstract:
  We generalise the notion of coherent states to arbitrary Lie algebras by
making an analogy with the GNS construction in $C^*$-algebras. The method is
illustrated with examples of semisimple and non-semisimple finite dimensional
Lie algebras as well as loop and Kac-Moody algebras.
  A deformed addition on the parameter space is also introduced simplifying
some expressions and some applications to conformal field theory is pointed
out, e.g. are differential operator and free field realisations found.
  PACS: 02.20.S, 03.65.F, 11.25.H
  Keywords: coherent states, Lie and Kac-Moody algebras, realisations.


title:
First Order Static Excitation Potential: Scheme for Excitation Energies
  and Transition Moments

abstract:
  We present an approximation scheme for the calculation of the principal
excitation energies and transition moments of finite many-body systems. The
scheme is derived from a first order approximation to the self energy of a
recently proposed extended particle-hole Green's function. A hermitian
eigenvalue problem is encountered of the same size as the well-known Random
Phase Approximation (RPA). We find that it yields a size consistent description
of the excitation properties and removes an inconsistent treatment of the
ground state correlation by the RPA. By presenting a hermitian eigenvalue
problem the new scheme avoids the instabilities of the RPA and should be well
suited for large scale numerical calculations. These and additional properties
of the new approximation scheme are illuminated by a very simple exactly
solvable model.


title:
Kinetic limit of N-body description of wave-particle self- consistent
  interaction

abstract:
  A system of N particles eN=(x1,v1,...,xN,vN) interacting self-consistently
with M waves Zn=An*exp(iTn) is considered. Hamiltonian dynamics transports
initial data (eN(0),Zn(0)) to (eN(t),Zn(t)). In the limit of an infinite number
of particles, a Vlasov-like kinetic equation is generated for the distribution
function f(x,v,t), coupled to envelope equations for the M waves. Any initial
data (f(0),Z(0)) with finite energy is transported to a unique (f(t),Z(t)).
Moreover, for any time T>0, given a sequence of initial data with N particles
distributed so that the particle distribution fN(0)-->f(O) weakly and with
Zn(0)-->Z(O) as N tends to infinity, the states generated by the Hamiltonian
dynamics at all time 0<t<T are such that (eN(t),Zn(t)) converges weakly to
(f(t),Z(t)). Comments: Kinetic theory, Plasma physics.


title: Nonlinear Dynamics of Accelerator via Wavelet Approach

abstract:
  In this paper we present the applications of methods from wavelet analysis to
polynomial approximations for a number of accelerator physics problems. In the
general case we have the solution as a multiresolution expansion in the base of
compactly supported wavelet basis. The solution is parametrized by the
solutions of two reduced algebraical problems, one is nonlinear and the second
is some linear problem, which is obtained from one of the next wavelet
constructions: Fast Wavelet Transform, Stationary Subdivision Schemes, the
method of Connection Coefficients. According to the orbit method and by using
construction from the geometric quantization theory we construct the symplectic
and Poisson structures associated with generalized wavelets by using
metaplectic structure. We consider wavelet approach to the calculations of
Melnikov functions in the theory of homoclinic chaos in perturbed Hamiltonian
systems and for parametrization of Arnold-Weinstein curves in Floer variational
approach.

categories: physics.acc-ph chao-dyn math-ph math.MP nlin.CD nlin.PS patt-sol physics.comp-ph


title: Radiation from a charged particle and radiation reaction -- revisited

abstract:
  We study the electromagnetic fields of an arbitrarily moving charged particle
and the radiation reaction on the charged particle using a novel approach. We
first show that the fields of an arbitrarily moving charged particle in an
inertial frame can be related in a simple manner to the fields of a uniformly
accelerated charged particle in its rest frame. Since the latter field is
static and easily obtainable, it is possible to derive the fields of an
arbitrarily moving charged particle by a coordinate transformation. More
importantly, this formalism allows us to calculate the self-force on a charged
particle in a remarkably simple manner. We show that the original expression
for this force, obtained by Dirac, can be rederived with much less computation
and in an intuitively simple manner using our formalism.


title: The Edmonds asymptotic formulae for the 3j and 6j symbols

abstract:
  The purpose of this paper is to provide definitions for, and proofs of, the
asymptotic formulae given by Edmonds, which relate the 3j and 6j symbols to
rotation matrices.


title: Angular Momentum, Quaternion, Octonion, and Lie-Super Algebra osp(1,2)

abstract:
  We will derive both quaternion and octonion algebras as the Clebsch-Gordan
algebras based upon the su(2) Lie algebra by considering angular momentum
spaces of spin one and three. If we consider both spin 1 and 1/2 states, then
the same method will lead to the Lie-super algebra osp(1,2). Also, the quantum
generalization of the method is discussed on the basis of the quantum group
$su_q(2)$.


title: Have We At Last Found The A-toms?

abstract:
  It is argued that the three families of quarks and leptons are the building
blocks of all matter and all forces (leaving out gravity) among them are
mediated by photons ($\gamma$), the weak bosons ($W^\pm$ and $Z$) and the
gluons.


title:
Nonlinear Dirac and diffusion equations in 1 + 1 dimensions from
  stochastic considerations

abstract:
  We generalize the method of obtaining the fundamental linear partial
differential equations such as the diffusion and Schrodinger equation, Dirac
and telegrapher's equation from a simple stochastic consideration to arrive at
certain nonlinear form of these equations. The group classification through one
parameter group of transformation for two of these equations is also carried
out.


title:
Parallel Tempering Algorithm for Conformational Studies of Biological
  Molecules

abstract:
  The effectiveness of a new algorithm, parallel tempering, is studied for
numerical simulations of biological molecules. These molecules suffer from a
rough energy landscape. The resulting slowing down in numerical simulations is
overcome by the new method. This is demonstrated by performing simulations with
high statistics for one of the simplest peptides, Met-enkephalin. The numerical
effectiveness of the new technique was found to be much better than traditional
methods and is comparable to sophisticated methods like generalized ensemble
techniques.

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


title:
Hybrid Quantum and Classical Mechanical Monte Carlo Simulations of the
  Interaction of Hydrogen Chloride with Solid Water Clusters

abstract:
  Monte Carlo simulations using a hybrid quantum and classical mechanical
potential were performed for crystal and amorphous-like HCl-water(n) clusters
The subsystem composed by HCl and one water molecule was treated within Density
Functional Theory, and a classical force field was used for the rest of the
system. Simulations performed at 200 K suggest that the energetic feasibility
of HCl dissociation strongly depends on its initial placement within the
cluster. An important degree of ionization occurs only if HCl is incorporated
into the surface. We observe that local melting does not play a crucial role in
the ionization process.


title: Atomic detection and matter-waves coherence

abstract:
  We analyze several models of atomic detectors in the context of the
measurement of coherence properties of matter waves. In particular, we show
that an ionization scheme measures normally-ordered correlation functions of
the Schr\"odinger field, in analogy with the optical situation. However, it
exhibits a sensitivity to exchange processes that is normally absent in optics.


title: Positronic lithium, an electronically stable Li-e$^+$ ground state

abstract:
  Calculations of the positron-Li system were performed using the Stochastic
Variational Method and yielded a minimum energy of -7.53208 Hartree for the L=0
ground state. Unlike previous calculations of this system, the system was found
to be stable against dissociation into the Ps + Li$^+$ channel with a binding
energy of 0.00217 Hartree and is therefore electronically stable. This is the
first instance of a rigorous calculation predicting that it is possible to
combine a positron with a neutral atom and form an electronically stable bound
state.


title: Stark Broadening of the B III 2s-2p Lines

abstract:
  We present a quantum-mechanical calculation of Stark line widths from
electron-ion collisions for the $2s_{1/2}-2p_{1/2,3/2}$, lambda = 2066 and 2067
A, resonance transitions in B III. The results confirm the previous
quantum-mechanical R-matrix calculations but contradict recent measurements and
semi-classical and some semi-empirical calculations. The differences between
the calculations can be attributed to the dominance of small L partial waves in
the electron-atom scattering, while the large Stark widths inferred from the
measurements would be substantially reduced if allowance is made for
hydrodynamic turbulence from high Reynolds number flows and the associated
Doppler broadening.


title:
Hydrogen atom moving across a strong magnetic field: analytical
  approximations

abstract:
  Analytical approximations are constructed for binding energies,
quantum-mechanical sizes and oscillator strengths of main radiative transitions
of hydrogen atoms arbitrarily moving in magnetic fields 10^{12}-10^{13} G.
Examples of using the obtained approximations for determination of maximum
transverse velocity of an atom and for evaluation of absorption spectra in
magnetic neutron star atmospheres are presented.


title:
Algebraic approach to q-deformed supersymmetric variants of the Hubbard
  model with pair hoppings

abstract:
  We construct two quantum spin chains Hamiltonians with quantum sl(2|1)
invariance. These spin chains define variants of the Hubbard model and describe
electron models with pair hoppings. A cubic algebra that admits the
Birman-Wenzl-Murakami algebra as a quotient allows exact solvability of the
periodic chain. The two Hamiltonians, respectively built using the
distinguished and the fermionic bases of U_q(sl(2|1)) differ only in the
boundary terms. They are actually equivalent, but the equivalence is non local.
Reflection equations are solved to get exact solvability on open chains with
non trivial boundary conditions. Two families of diagonal solutions are found.
The centre and the Scasimirs of the quantum enveloping algebra of sl(2|1)
appear as tools for the construction of exactly solvable Hamiltonians.

categories: math-ph cond-mat.str-el hep-th math.MP math.QA


title: Nonlinear Magnetosonic Waves in a Multi-Ion-Species Plasma

abstract:
  Magnetosonic waves are intensively studied due to their importance in space
plasmas and also in fusion plasmas where they are used in particle acceleration
and heating experiments. In the present paper we investigate the magnetosonic
waves propagating in a multi-ion-species plasma perpendicular to an external
magnetic field. Due to the presence of several ion species, this mode splits
into two branches: high- and low-frequency modes. This opens a new channel of
nonlinear interactions (between these two modes), and qualitatively changes the
picture of turbulence in the long-wave region. Using the exact kinetic
approach, we derive a general system describing the propagation of nonlinearly
coupled high- and low-frequency waves. This system includes the KdV,
Boussinesq, and Zakharov equations as limiting cases. Solitary solutions of the
system of coupled equations are obtained.


title:
Hydrogen molecule in a magnetic field: The lowest states of the Pi
  manifold and the global ground state of the parallel configuration

abstract:
  The electronic structure of the hydrogen molecule in a magnetic field is
investigated for parallel internuclear and magnetic field axes. The lowest
states of the $\Pi$ manifold are studied for spin singlet and triplet$(M_s =
-1) $ as well as gerade and ungerade parity for a broad range of field
strengths $0 \leq B \leq 100 a.u.$ For both states with gerade parity we
observe a monotonous decrease in the dissociation energy with increasing field
strength up to $B = 0.1 a.u.$ and metastable states with respect to the
dissociation into two H atoms occur for a certain range of field strengths. For
both states with ungerade parity we observe a strong increase in the
dissociation energy with increasing field strength above some critical field
strength $B_c$. As a major result we determine the transition field strengths
for the crossings among the lowest $^1\Sigma_g$, $^3\Sigma_u$ and $^3\Pi_u$
states. The global ground state for $B \lesssim 0.18 a.u.$ is the strongly
bound $^1\Sigma_g$ state. The crossings of the $^1\Sigma_g$ with the
$^3\Sigma_u$ and $^3\Pi_u$ state occur at $B \approx 0.18$ and $B \approx0.39
a.u.$, respectively. The transition between the $^3\Sigma_u$ and $^3\Pi_u$
state occurs at $B \approx 12.3 a.u.$ Therefore, the global ground state of the
hydrogen molecule for the parallel configuration is the unbound $^3\Sigma_u$
state for $0.18 \lesssim B \lesssim 12.3 a.u.$ The ground state for $B \gtrsim
12.3 a.u.$ is the strongly bound $^3\Pi_u$ state. This result is of great
relevance to the chemistry in the atmospheres of magnetic white dwarfs and
neutron stars.


title: Fractional Talbot effect in phase space: A compact summation formula

abstract:
  A phase space description of the fractional Talbot effect, occurring in a
one-dimensional Fresnel diffraction from a periodic grating, is presented.
Using the phase space formalism a compact summation formula for the Wigner
function at rational multiples of the Talbot distance is derived. The summation
formula shows that the fractional Talbot image in the phase space is generated
by a finite sum of spatially displaced Wigner functions of the source field.


title: Influence of Dynamics on Magic Numbers for Silicon Clusters

abstract:
  We present the results of over 90 tight-binding molecular-dynamics
simulations of collisions between three- and five-atom silicon clusters, at a
system temperature of 2000K. Much the most likely products are found to be two
'magic' four-atom clusters. We show that previous studies, which focused on the
equilibrium binding energies of clusters of different sizes, are of limited
relevance, and introduce a new effective binding energy which incorporates the
highly anharmonic dynamics of the clusters. The inclusion of dynamics enhances
the magic nature of both Si4 and Si6 and destroys that of Si7.


title: An Uncontrolled Toy That Can Walk But Cannot Stand Still

abstract:
  We built a simple two-leg toy that can walk stably with no control system. It
walks downhill powered only by gravity. It seems to be the first McGeer-like
passive-dynamic walker that is statically unstable in all standing positions,
yet is stable in motion. It is one of few known mechanical devices that are
stable near a statically unstable configuration but do not depend on spinning
parts. Its design is loosely based on simulations which do not predict its
observed stability. Its motion highlights the possible role of uncontrolled
nonholonomic mechanics in balance.


title: Cosmic Tests for a More Explicit Equivalence Principle

abstract:
  According to this principle, the relativistic changes occurring to the
bodies, after velocity changes, cannot be detected by observers moving with
them because bodies and stationary radiations change in identical proportion
after identical circumstances, i.e, because bodies and stationary radiations
have identical relativistic laws with respect to any fixed observer.
Effectively the theoretical properties of particle models made up of stationary
radiations agree with special relativity, quantum mechanics and the
gravitational (G) tests. They fix lineal properties for all of them: the G
fields, the black holes (BHs) and the universe. The BHs, after absorbing
radiation, must return to the gas state. An eventual universe expansion cannot
change any relative distance because the G expansion of matter occurs in
identical proportion. This fixes a new kind of universe. In it matter evolves
in closed cycles, between gas and BH states and vice versa, indefinitely.
Galaxies and clusters must evolve rather cyclically between luminous and black
states. Most of the G potential energy of a matter cycle must be released
around neutron star and black hole boundaries. Nuclear stripping reactions
would transform G energy into nuclear and kinetic energies. This accounts for
many non well explained phenomena in astrophysics. This work has been
published, in more detail, in a book.


title:
On the difference between the charge-free and the charge-neutral
  solutions of Maxwell equations

abstract:
  It is conventionally believed that solutions of so called "free" Maxwell
equations for \varrho=0 (density of charge) describe the free electromagnetic
field in empty space (if one considers the free field as a field, whose flux
lines neither begin nor end in a charge). We consider three types of regions:
(i) "isolated charge-free" region (where all electric fields, generated by
charges outside that particular region, are zero), for example, inside a hollow
conductor of any shape or in a free-charge Universe; (ii) ``non-isolated
charge-free" region (where all electric fields, generated by charges outside
that particular region, are not zero) and (iii) "charge-neutral" region (where
point charges exist but their algebraic sum is zero). The paper notes that
there are two families of solutions: (1) In "isolated charge-free" regions
electric free field does not exist in the context of Maxwell's equations, but
there may exist a time-independent background magnetic field. (2) In both
"charge-neutral" and "non-isolated charge-free" regions where the homogeneous
condition \varrho=0 also holds, Maxwell's equation for electric field have
non-zero solution, as in the conventional view, but this solution is not free
field. We mention some implications related to free-electromagnetic fields and
the simplest charge-neutral universe.


title:
Does the electromagnetic field of an accelerated charge satisfy Maxwell
  equations?

abstract:
  We considered the electromagnetic field of a charge moving with a constant
acceleration along an axis. We found that this field obtained from the
Lienard-Wiechert potentials does not satisfy Maxwell equations.


title: Almost Parity Structure, Connections and Vielbeins in BV Geometry

abstract:
  We observe that an anti-symplectic manifold locally always admits a parity
structure. The parity structure can be viewed as a complex-like structure on
the manifold. This induces an odd metric and its Levi-Civita connection, and
thereby a new notion of an odd Kaehler geometry. Oversimplified, just to
capture the idea, the bosonic variables are ``holomorphic'', while the
fermionic variables are ``anti-holomorphic''. We find that an odd Kaehler
manifold in this new ``complex'' sense has a nilpotent odd Laplacian iff it is
Ricci-form-flat. The local cohomology of the odd Laplacian is derived. An odd
Calabi-Yau manifold has locally a canonical volume form. We suggest that an odd
Calabi-Yau manifold is the natural geometric notion to appear in covariant
BV-quantization. Finally, we give a vielbein formulation of anti-symplectic
manifolds.


title: Superluminal pulse transmission through a phase-conjugating mirror

abstract:
  We theoretically analyze wave packet transmission through a phase-conjugating
mirror and show that the transmission of a suitably chosen input pulse is
superluminal, i.e. the peak of the pulse emerges from the mirror before the
time it takes to travel the same distance in vacuum. This pulse reshaping
effect can be attributed directly to the dispersion relation in the nonlinear
medium constituting the mirror. Thus, for the first time a connection is laid
between optical phase conjugation and superluminal behavior. In view of its
additional amplifying ability, a phase-conjugating mirror is a most promising
candidate for an experimental observation of tachyonic signatures.


title:
Parallel Implementations of the Split-Step Fourier Method for Solving
  Nonlinear Schr\"odinger Systems

abstract:
  We present a parallel version of the well-known Split-Step Fourier method
(SSF) for solving the Nonlinear Schr\"odinger equation, a mathematical model
describing wave packet propagation in fiber optic lines. The algorithm is
implemented under both distributed and shared memory programming paradigms on
the Silicon Graphics/Cray Research Origin 200. The 1D Fast-Fourier Transform
(FFT) is parallelized by writing the 1D FFT as a 2D matrix and performing
independent 1D sequential FFTs on the rows and columns of this matrix. We can
attain almost perfect speedup in SSF for small numbers of processors depending
on both problem size and communication contention. The parallel algorithm is
applicable to other computational problems constrained by the speed of the 1D
FFT.


title: Geometric quantization on symplectic fiber bundles

abstract:
  Consider a fiber bundle in which the total space, the base space and the
fiber are all symplectic manifolds. We study the relations between the
quantization of these spaces. In particular, we discuss the geometric
quantization of a vector bundle, as oppose to a line bundle, over the base
space that recovers the standard geometric quantization of the total space.


title:
Fluctuational phase-flip transitions in parametrically pumped
  oscillators

abstract:
  We analyze the rates of noise-induced transitions between period-two
attractors. The model investigated is an underdamped oscillator parametrically
driven by a field at nearly twice the oscillator eigenfrequency. The activation
energy of the transitions is analyzed as a function of the frequency detuning
and field amplitude scaled by the damping and nonlinearity parameters of the
oscillator. The parameter ranges where the system is bi- and tristable are
investigated. Explicit results are obtained in the limit of small damping (or
strong driving), and near bifurcation points.


title: On the "circular vacuum noise" in electron storage rings

abstract:
  We discuss the proposal of Bell and Leinaas (BL) to measure the circular
Unruh effect in storage rings. The ideal concept `circular Unruh effect' has a
more realistic correspondent such as `circular vacuum noise' used by Shin
Takagi [Prog. Theor. Phys. Suppl. 88, 1 (1986)] The BL resonance behavior does
not fit to the SPEAR first order betatron resonance at 3.605 GeV, but of
course, the real experimental situation is much more complicated,
corresponding, as a matter of fact, to an even more general term that one may
call `synchrotron noise'. In the final section we focus on radiometric aspects
of storage ring physics, such as the problem of establishing better quantum
field radiometric standards at high energies. The Unruh-like effect could be a
useful guide for that purpose


title: A theory for the membrane potential of cells

abstract:
  We give an explicit formula for the membrane potential of cells in terms of
the intracellular and extracellular ionic concentrations, and derive equations
for the ionic currents that flow through channels, exchangers and electrogenic
pumps based on simple energy considerations and conservation laws. We
demonstrate that the work done by the pump is equal to the potential energy of
the cell plus the energy loss due to the downhill ionic fluxes through the
channels and the exchanger. Our equations predict osmotic pressure variations.
The theory is illustrated in a simple model of spontaneously active cells in
the cardiac pacemaker. The simulated action potential and the five currents in
the model are in excellent agreement with experiments. The model predicts the
experimental observed intracellular ionic concentration of potassium, calcium
and sodium. We do not see any drift of the values for the concentrations in a
long time simulation, instead we can obtain the same asymptotic values starting
with equal intracellular and extracellular ionic concentrations.


title:
Propagation of an electromagnetic pulse through a waveguide with a
  barrier: A time domain solution within classical electrodynamics

abstract:
  An electromagnetic truncated Gaussian pulse propagates through a waveguide
with piecewise different dielectric constants. The waveguide contains a
barrier, namely a region of a lower dielectric constant compared to the
neighboring regions. This set-up yields a purely imaginary wave vector in the
region of the barrier ('electromagnetic tunneling'). We exactly calculate the
time-dependent Green's function for a slightly simplified dispersion relation.
In order to observe the plain tunneling effect we neglect the distortions
caused by the wave guide in obtaining the transmitted pulse. The wave front of
the pulse travels with the vacuum speed of light. Nevertheless, behind the
barrier, the maximum of the transmitted pulse turns up at an earlier time than
in the case without an barrier. This effect will be explained in terms of the
energy flow across the barrier. The solutions obtained reproduce the shape of
the pulses measured in the tunneling experiments of Enders and Nimtz [J. Phys.
(France) I2, 1693 (1992); Phys. Rev. E48, 632 (1993); Phys. Rev. B47, 9605
(1993); J. Phys. (France) I3, 1089 (1993); 4, 565 (1994)].


title: A superconductive undulator with period length of 3.8 mm

abstract:
  During the last years several attempts were undertaken to decrease the period
length of undulators to the mm range. In this paper, a novel type of an
in-vacuum undulator is described which is built with superconductive wires. The
period length of this special device is 3.8 mm. In principle, it is possible to
decrease this period length even further. A 100 period long undulator has been
built and will be tested with beam in the near future.


title: The 3-dimensional Fourier grid Hamiltonian method

abstract:
  A method to compute the bound state eigenvalues and eigenfunctions of a
Schr\"{o}dinger equation or a spinless Salpeter equation with central
interaction is presented. This method is the generalization to the
three-dimensional case of the Fourier grid Hamiltonian method for
one-dimensional Schr\"{o}dinger equation. It requires only the evaluation of
the potential at equally spaced grid points and yields the radial part of the
eigenfunctions at the same grid points. It can be easily extended to the case
of coupled channel equations and to the case of non-local interactions.


title:
The hydrogen molecule in magnetic fields: The ground states of the Sigma
  manifold of the parallel configuration

abstract:
  The electronic structure of the hydrogen molecule is investigated for the
parallel configuration. The ground states of the Sigma manifold are studied for
ungerade and gerade parity as well as singlet and triplet states covering a
broad regime of field strengths from B = 0 up to B = 100a.u. A variety of
interesting phenomena can be observed. For the ^1Sigma_g state we found a
monotonous decrease of the equilibrium distance and a simultaneously increase
of the dissociation energy with growing magnetic field strength. The ^3\Sigma_g
state is shown to develop an additional minimum which has no counterpart in
field-free space. The ^1\Sigma_u state shows a monotonous increase in the
dissociation energy with first increasing and than decreasing internuclear
distance of the minimum. For this state the dissociation channel is H_2 to H^-
+ H^+ for magnetic-field strengths B greater than 20a.u. due to the existence
of strongly bound H^- states in strong magnetic fields. The repulsive
^3\Sigma_u state possesses a very shallow van der Waals minimum for
magnetic-field strengths smaller than 1.0a.u. within the numerical accuracy of
our calculations. The ^1\Sigma_g and ^3\Sigma_u states cross as a function of B
and the ^3\Sigma_u state, which is an unbound state, becomes the ground state
of the hydrogen molecule in magnetic fields B greater than 0.2a.u. This is of
particular interest for the existence of molecular hydrogen in the vicinity of
white dwarfs. In superstrong fields the ground state is again a strongly bound
state, the ^3\Pi_u state.


title:
A Unified Approach to the Classical Statistical Analysis of Small
  Signals

abstract:
  We give a classical confidence belt construction which unifies the treatment
of upper confidence limits for null results and two-sided confidence intervals
for non-null results. The unified treatment solves a problem (apparently not
previously recognized) that the choice of upper limit or two-sided intervals
leads to intervals which are not confidence intervals if the choice is based on
the data. We apply the construction to two related problems which have recently
been a battle-ground between classical and Bayesian statistics: Poisson
processes with background, and Gaussian errors with a bounded physical region.
In contrast with the usual classical construction for upper limits, our
construction avoids unphysical confidence intervals. In contrast with some
popular Bayesian intervals, our intervals eliminate conservatism (frequentist
coverage greater than the stated confidence) in the Gaussian case and reduce it
to a level dictated by discreteness in the Poisson case. We generalize the
method in order to apply it to analysis of experiments searching for neutrino
oscillations. We show that this technique both gives correct coverage and is
powerful, while other classical techniques that have been used by neutrino
oscillation search experiments fail one or both of these criteria.


title: Sampling quantum phase space with squeezed states

abstract:
  We study the application of squeezed states in a quantum optical scheme for
direct sampling of the phase space by photon counting. We prove that the
detection setup with a squeezed coherent probe field is equivalent to the
probing of the squeezed signal field with a coherent state. An example of the
Schroedinger cat state measurement shows that the use of squeezed states allows
one to detect clearly the interference between distinct phase space components
despite losses through the unused output port of the setup.


title: Theoretical and Numerical studies of the positions of cold trapped ions

abstract:
  We examine the properties of cold ions confined by a Paul trap in a linear
crystal configuration, a system of considerable current interest due to its
application to practical quantum computation. Using a combination of
theoretical and numerical calculation, a semi- empirical formula for the
positions of the ions is derived.


title:
Failure of Lorentz-Dirac Approach to Radiation Reaction for Extremely
  Large Velocities ?

abstract:
  On the model of moving rigid charged body is shown that the Lorentz-Dirac
approach to radiation reaction in classical electrodynamics does not work for
trajectories of body close to the light cone.


title: Luminescent Bolometer and Neutrino Physics

abstract:
  The luminescent bolometer, proposed in 1988, is now seriously considered for
several applications in nuclear and particle physics: dark matter searches,
double beta decays, low energy neutrino physics, heavy ion physics... It is
also a very promising device for basic condensed-matter physics and chemistry
experiments, and may lead to astrophysical applications. The luminescent
bolometer is based on the simultaneous detection of light and phonons, allowing
for particle identification and for a detailed study of the detector response.
Digitized analysis of the signals produced in several sensors installed on the
same crystal is then a very powerful tool. Superconducting sensors allow to
detect the scintillation light pulse followed by the delayed front of phonons,
and can be extremely sensitive leading to single photon counting in the visible
range. They also provide information on the position of the event inside the
absorber, and can be fast enough for all proposed applications. The luminescent
bolometer, with superconducting sensors, appears extremely promising for real
time $solar$ neutrino experiments based on new indium single crystal
scintillators. We focus on this particular application, discussing the status
of the art as well as open problems and presenting an updated description of a
full scale real time solar neutrino experiment sensitive to the low energy
sector. Other applications of the luminescent bolometer (e.g. spectroscopy or
neutrino detection at reactors), involving indium compounds and other single
crystal scintillators, are equally considered and discussed in detail.


title: Recoil correction to the ground state energy of hydrogenlike atoms

abstract:
  The recoil correction to the ground state energy of hydrogenlike atoms is
calculated to all orders in \alpha Z in the range Z = 1-110. The nuclear size
corrections to the recoil effect are partially taken into account. In the case
of hydrogen, the relativistic recoil correction beyond the Salpeter
contribution and the nonrelativistic nuclear size correction to the recoil
effect, amounts to -7.2(2) kHz. The total recoil correction to the ground state
energy in hydrogenlike uranium (^{238}U^{91+}) constitutes 0.46 eV.


title: Integrating Factors and ODE Patterns

abstract:
  A systematic algorithm for building integrating factors of the form mu(x,y')
or mu(y,y') for non-linear second order ODEs is presented. When such an
integrating factor exists, the algorithm determines it without solving any
differential equations. Examples of ODEs not having point symmetries are shown
to be solvable using this algorithm. The scheme was implemented in Maple, in
the framework of the ODEtools package and its ODE-solver. A comparison between
this implementation and other computer algebra ODE-solvers in tackling
non-linear examples from Kamke's book is shown.


title: Semiclassical theory of vibrational energy relaxation

abstract:
  A theory of vibrational energy relaxation based on a semiclassical treatment
of the quantum master equation is presented. Using new results on the
semiclassical expansion of dipole matrix elements, we show that in the
classical limit the master equation reduces to the Zwanzig energy diffusion
equation. The leading quantum corrections are determined and discussed for the
harmonic and Morse potentials.


title:
Extended Classical Over-Barrier Model for Collisions of Highly Charged
  Ions with Conducting and Insulating Surfaces

abstract:
  We have extended the classical over-barrier model to simulate the
neutralization dynamics of highly charged ions interacting under grazing
incidence with conducting and insulating surfaces. Our calculations are based
on simple model rates for resonant and Auger transitions. We include effects
caused by the dielectric response of the target and, for insulators, localized
surface charges. Characteristic deviations regarding the charge transfer
processes from conducting and insulating targets to the ion are discussed. We
find good agreement with previously published experimental data for the image
energy gain of a variety of highly charged ions impinging on Au, Al, LiF and KI
crystals.


title:
Interactions of Ar(9+) and metastable Ar(8+) with a Si(100) surface at
  velocities near the image acceleration limit

abstract:
  Auger LMM spectra and preliminary model simulations of Ar(9+) and metastable
Ar(8+) ions interacting with a clean monocrystalline n-doped Si(100) surface
are presented. By varying the experimental parameters, several yet undiscovered
spectroscopic features have been observed providing valuable hints for the
development of an adequate interaction model. On our apparatus the ion beam
energy can be lowered to almost mere image charge attraction. High data
acquisition rates could still be maintained yielding an unprecedented
statistical quality of the Auger spectra.


title: Real Spectra in Non-Hermitian Hamiltonians Having PT Symmetry

abstract:
  The condition of self-adjointness ensures that the eigenvalues of a
Hamiltonian are real and bounded below. Replacing this condition by the weaker
condition of ${\cal PT}$ symmetry, one obtains new infinite classes of complex
Hamiltonians whose spectra are also real and positive. These ${\cal PT}$
symmetric theories may be viewed as analytic continuations of conventional
theories from real to complex phase space. This paper describes the unusual
classical and quantum properties of these theories.

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


title: Deformations of classical geometries and integrable systems

abstract:
  A generalization of the notion of a (pseudo-) Riemannian space is proposed in
a framework of noncommutative geometry. In particular, there are parametrized
families of generalized Riemannian spaces which are deformations of classical
geometries. We also introduce harmonic maps on generalized Riemannian spaces
into Hopf algebras and make contact with integrable models in two dimensions.

categories: math-ph gr-qc hep-th math.MP math.QA nlin.SI


title:
The instrument response function in air-based scanning tunneling
  microscopy

abstract:
  The distinction between point and line resolution in transmission electron
microscopy (TEM) arises because an ability to image sub-0.2 nm fringes is a
necessary, but not a sufficient, condition for imaging individual atoms. In
scanned tip microscopy, as in TEM, empirical data on instrument response should
precede assertions about point resolution. In the ``slow scan limit'',
time-domain noise and geometry effects decouple, and tip shape can take on the
role of a 2-dimensional impulse response function. We indicate here that
nuclear track pits can be used to quantitatively measure tip geometry with
nanometer-scale resolution in three dimensions, that stationary tip images
provide a robust measure of time-domain instabilities, and that when these data
are taken before and after imaging an unknown, images with instrument response
quantitatively constrained by experiment are possible. Specimen-induced tip
effects also become measurable in situ.


title: Some aspects of noncommutative geometry and physics

abstract:
  An introduction is given to some selected aspects of noncommutative geometry.
Simple examples in this context are provided by finite sets and lattices. As an
application, it is explained how the nonlinear Toda lattice and a discrete time
version of it can be understood as generalized sigma-models based on
noncommutative geometries. In particular, in this way one achieves a simple
understanding of the complete integrability of the Toda lattice. Furthermore,
generalized metric structures on finite sets and lattices are briefly
discussed.


title: Lorentz Symmetry Violation and High-Energy Cosmic Rays

abstract:
  We discuss possible violations of Poincare's relativity principle at energy
scales close to Planck scale and point out the potentialities of high-energy
cosmic-ray physics to uncover these new phenomena.


title:
Perturbation of an eigenvalue from a dense point spectrum: a general
  Floquet Hamiltonian

abstract:
  We consider a perturbed Floquet Hamiltonian $-i\partial_t + H + \beta
V(\omega t)$ in the Hilbert space $L^2([0,T],E,dt)$. Here $H$ is a self-adjoint
operator in $E$ with a discrete spectrum obeying a growing gap condition,
$V(t)$ is a symmetric bounded operator in $E$ depending on $t$
$2\pi$-periodically, $\omega = 2\pi/T$ is a frequency and $\beta$ is a coupling
constant. The spectrum $Spec(-i\partial_t + H)$ of the unperturbed part is pure
point and dense in $R$ for almost every $\omega$. This fact excludes
application of the regular perturbation theory. Nevertheless we show, for
almost all $\omega$ and provided $V(t)$ is sufficiently smooth, that the
perturbation theory still makes sense, however, with two modifications. First,
the coupling constant is restricted to a set $I$ which need not be an interval
but 0 is still a point of density of $I$. Second, the Rayleigh-Schrodinger
series are asymptotic to the perturbed eigen-value and the perturbed
eigen-vector.

categories: math-ph math.FA math.MP nlin.CD quant-ph


title: Chemical dynamics versus transport dynamics in a simple model

abstract:
  Reaction equations of homogeneously mixed pollutants in the atmosphere can
lead to non-stationary periodic solutions. It is important to know in which
respect these solutions are modified under the influence of the atmospheric
currents. We investigate this question in a very simple model: The reaction
equations are modeled by the equations of the brusselator and the currents are
represented by an isolated vortex. In the limit of high vortex currents we find
again the homogeneous solutions whereas for smaller currents complicated
spatial and temporal patterns emerge. The role of the diffusion as a singular
perturbation is investigated.


title:
Charge Transfer in Cluster-Atom Collisions Studied with Non-Adiabatic
  Quantum Molecular Dynamics

abstract:
  Charge transfer in collisions of Na_n^+ cluster ions with Cs atoms is
investigated theoretically in the microscopic framework of non-adiabatic
quantum molecular dynamics. The competing reaction channels and related
processes affecting the charge transfer (electronic excitations, fragmentation,
temperature) are described. Absolute charge transfer cross sections for
Na_n^+(2.7 keV) + Cs --> Na_n + Cs^+ have been calculated in the size range 4
<= n <= 11 reproducing the size dependence of the experimental cross sections.
The energy dependence of the cross section is predicted for n=4,7,9. An exotic
charge transfer channel producing Cs^- is found to have a finite probability.