title: What does `rho-exchange' in piN scattering mean?

abstract:
  We present an alternative method for calculating amplitudes for correlated pi
pi exchange in the ``sigma'' and rho channel in piN scattering. Starting from a
fixed mass meson exchange potential, we introduce the width of the exchanged
particles by integrating over a mass spectral function. The spectral functions
are constructed from the pseudoempirical N\bar{N} -> pi pi data. Using this
approach we develop a prescription for resolving ambiguities of the correlated
pi pi exchange in the rho channel that occur when different dispersion
theoretical formulations of rho exchange are used to construct piN potentials.


title:
Deuteron electromagnetic properties and the viability of effective field
  theory methods in the two-nucleon system

abstract:
  The central tenet of effective theory is that the details of short-distance
physics will not have a significant impact on low-energy observables. Here we
perform an analysis of electron-deuteron scattering at low momentum transfers
which is based on effective field theory. We show that in our approach the
deuteron electromagnetic form factors $F_C$ and $F_M$ indeed are largely
insensitive to the short-range $NN$ potential at momenta $Q$ up to about 700
MeV. We also find that the effective field theory approach to deuteron
electromagnetic structure provides a systematic justification for many features
which have been seen in potential model calculations of the same quantities.


title:
Isospin singlet (pn) pairing and quartetting contribution to the binding
  energy of nuclei

abstract:
  Isospin singlet (pn) pairing as well as quartetting in nuclei is expected to
arise near the symmetry line $N=Z$. Empirical values can be deduced from the
nuclear binding energies applying special filters. Within the local density
approximation, theoretical estimates for finite nuclei are obtained from
results for the condensation energy of asymmetric nuclear matter. It is shown
that the isospin singlet condensation energy drops down abruptly for |N-Z|~4
for medium nuclei in the region A=40. Furthermore, alpha-like quartetting and
the influence of excitations are discussed.


title: An algebraic model of baryon spectroscopy

abstract:
  We discuss recent calculations of the mass spectrum, electromagnetic and
strong couplings of baryon resonances. The calculations are done in a
collective constituent model for the nucleon, in which the resonances are
interpreted as rotations and vibrations of a symmetric top with a prescribed
distribution of the charge and magnetization. We analyze recent data on
eta-photo- and eta-electroproduction, and the tensor analyzing power in
deuteron scattering.


title:
Probing halo nucleus structure through intermediate energy elastic
  scattering

abstract:
  This work addresses the question of precisely what features of few body
models of halo nuclei are probed by elastic scattering on protons at high
centre-of-mass energies. Our treatment is based on a multiple scattering
expansion of the proton-projectile transition amplitude in a form which is well
adapted to the weakly bound cluster picture of halo nuclei. In the specific
case of $^{11}$Li scattering from protons at 800 MeV/u we show that because
core recoil effects are significant, scattering crosssections can not, in
general, be deduced from knowledge of the total matter density alone.
  We advocate that the optical potential concept for the scattering of halo
nuclei on protons should be avoided and that the multiple scattering series for
the full transition amplitude should be used instead.


title:
Relativistic effects on the neutron charge form factor in the
  constituent quark model

abstract:
  The neutron charge form factor GEn(Q**2) is investigated within a constituent
quark model formulated on the light-front. It is shown that, if the quark
initial motion is neglected in the Melosh rotations, the Dirac neutron form
factor F1n(Q**2)$ receives a relativistic correction which cancels exactly
against the Foldy term in GEn(Q**2), as it has been recently argued by Isgur.
Moreover, at the same level of approximation the ratio of the proton to neutron
magnetic form factors GMp(Q**2) / GMn(Q**2) is still given by the naive
SU(6)-symmetry expectation, -3/2. However, it is also shown that the full
Melosh rotations break SU(6) symmetry, giving rise to GEn(Q**2) =/ 0 and
GMp(Q**2)/GMn(Q**2) =/ -3/2 even when a SU(6)-symmetric canonical wave function
is assumed. It turns out that relativistic effects alone cannot explain
simultaneously the experimental data on GEn(Q**2)$ and GMp(Q**2)/GMn(Q**2).


title: Evidence for a missing nucleon resonance in kaon photoproduction

abstract:
  New SAPHIR p(gamma,K+)Lambda total cross section data show a resonance
structure at a total c.m. energy around 1900 MeV. We investigate this feature
with an isobar model and find that the structure can be well explained by
including a new D_{13} resonance at 1895 MeV. Such a state has been predicted
by a relativistic quark model at 1960 MeV with significant gamma-N and K-Lambda
branching ratios. We demonstrate how the measurement of the photon asymmetry
can be used to further study this resonance. In addition, verification of the
predicted large decay widths into the eta-N and eta'-N channels would allow
distinguishing between other nearby D_{13} states.


title:
Coherent electromagnetic heavy ion reactions: (1) exact treatment of
  pair production and ionization; (2) mutual Coulomb dissociation

abstract:
  Some recent theoretical results on coherent electromagnetic processes in
ultrarelativistic heavy ion reactions are surveyed.


title:
Theoretical predictions of residues cross sections of superheavy
  elements

abstract:
  Dynamical reaction theories are reviewed for synthesis of superheavy
elements. Characteristic features of formation and surviving are discussed with
reference to possible incident channels. Theoretical predictions are presented
on favorable incident channels and on optimum energies for synthesis of Z=114.


title: Baryon flow from SIS to AGS energies

abstract:
  We analyze the baryon sideward and elliptic flow from SIS (0.25 $\sim$ 2 A
GeV) to AGS (2 $\sim 11.0A$GeV) energies for Au + Au collisions in the
relativistic transport model RBUU that includes all baryon resonances up to a
mass of 2 GeV as well as string degrees of freedom for the higher mass
continuum. There are two factors which dominantly determine the baryon flow at
these energies: the momentum dependence of the scalar and vector potentials and
the resonance-string degrees of freedom. We fix the explicit momentum
dependence of the nucleon-meson couplings within the NL3 parameter set by the
nucleon optical potential up to 1 GeV of kinetic energy. When assuming the
optical potential to vanish identically for $E_{kin} \geq 3.5$ GeV we
simultaneously reproduce the sideward flow data of the FOPI, EOS, E895 and E877
collaborations, the elliptic flow data of the EOS, E895 and E877
collaborations, and approximately the rapidity and transverse mass distribution
of protons at AGS energies. The gradual change from hadronic to string degrees
of freedom with increasing bombarding energy can be viewed as a transition from
{\it hadronic} to {\it string} matter, i.e. a dissolution of hadrons.


title:
Overlap functions in correlation methods and quasifree nucleon knockout
  from $^{16}$O

abstract:
  The cross sections of the ($e,e'N$) and ($\gamma,p$) reactions on $^{16}$O
are calculated, for the transitions to the $1/2^{-}$ ground state and the first
$3/2^{-}$ excited state of the residual nucleus, using single-particle overlap
functions obtained on the basis of one-body density matrices within different
correlation methods. The electron-induced one-nucleon knockout reaction is
treated within a nonrelativistic DWIA framework. The theoretical treatment of
the ($\gamma,p$) reaction includes both contributions of the direct knockout
mechanism and of meson-exchange currents. The results are sensitive to details
of the different overlap functions. The consistent analysis of the reaction
cross sections and the comparison with the experimental data make it possible
to study the nucleon--nucleon correlation effects.


title:
Initial State Energy Loss Dependence of J/Psi and Drell-Yan in
  Relativistic Heavy Ion Collisions

abstract:
  We present a Glauber-based study of J/Psi and Drell-Yan yields in
nucleus-nucleus collisions. Using this approach, we have investigated the
impact of energy loss by the colliding nuclei on observed yields and transverse
momentum spectra of J/Psi and Drell-Yan. These studies permit an assessment of
the importance of initial state energy loss in relation to "anomalous" J/Psi
suppression.


title:
Invariant amplitudes for coherent electromagnetic pseudoscalar
  production from a spin-one target (II): crossing, multipoles and observables

abstract:
  The formal properties of the recently derived set of linearly independent
invariant amplitudes for the electromagnetic production of a pseudoscalar
particle from a spin-one particle have been further exploited. The crossing
properties are discussed in detail. Since not all of the amplitudes have simple
crossing behaviour, we introduce an alternative set of basic amplitudes which
are either symmetric or antisymmetric under crossing. The multipole
decomposition is given, and the representation of the multipoles as integrals
over the invariant functions weighted with Legendre polynomials is derived.
Furthermore, differential cross section and polarization observables are
expressed in terms of the corresponding invariant functions.


title: Functional approach to the non-mesonic decay of Lambda-hypernuclei

abstract:
  We present an evaluation of the non-mesonic decay widths for
Lambda-hypernuclei (Lambda N --> NN, Lambda NN --> NNN) within the framework of
the polarization propagator method. The full Lambda self-energy is evaluated
microscopically in nuclear matter by using the functional approach, which
supplies a theoretically well grounded approximation scheme for the
classification of the relevant diagrams, according to the prescriptions of the
bosonic loop expansion. We employ average Fermi momenta, suitably adapted to
different mass number regions (medium-light, medium and heavy hypernuclei).
Moreover, we study the dependence of the decay rates on the NN and Lambda-N
short range correlations. With a proper choice of the parameters which control
these correlations in the new approximation scheme, it is possible to reproduce
the experimental decay widths for A > 10 hypernuclei.


title:
Structure of the vacuum states in the presence of isovector and
  isoscalar pairing correlations

abstract:
  The long standing problem of proton-neutron pairing and, in particular, the
limitations imposed on the solutions by the available symmetries, is revisited.
We look for solutions with non-vanishing expectation values of the proton, the
neutron and the isoscalar gaps. For an equal number of protons and neutrons we
find two solutions where the absolute values of proton and neutrons gaps are
equal but have the same or opposite sign. The behavior and structure of these
solutions differ for spin saturated (single l-shell) and spin unsaturared
systems (single j-shell). In the former case the BCS results are checked
against an exact calculation.


title: Scalar Isoscalar pion pairs in nuclei and the A(pi,pipi)X reaction

abstract:
  The reaction A(pi,pi pi)X has been studied at low energies, paying particular
attention to the interaction of the two final pions in the scalar isoscalar
(I=J=0) channel. We have developed a microscopic model for the pion production,
and then implemented the two pion final state interaction by using the results
of a non-perturbative unitary coupled-channels method based in the standard
chiral Lagrangians. The resulting model, describes well the reaction on the
nucleon for all different isospin channels.
  Finally, we have considered the reaction in nuclei. Our calculation takes
into account Fermi motion, Pauli blocking, pion absorption, and also the strong
modification of the pi-pi interaction in the nuclear medium.


title:
Roles of proton-neutron interactions in alpha-like four-nucleon
  correlations

abstract:
  An extended pairing plus QQ force model, which has been shown to successfully
explain the nuclear binding energy and related quantities such as the symmetry
energy, is applied to study the alpha-like four-nucleon correlations in
1f_{7/2} shell nuclei.
  The double difference of binding energies, which displays a characteristic
behavior at $N \approx Z$, is interpreted in terms of the alpha-like
correlations. Important roles of proton-neutron interactions forming the
alpha-like correlated structure are discussed.


title:
Fine structure of Vavilov-Cherenkov radiation near the Cherenkov
  threshold

abstract:
  We analyze the Vavilov-Cherenkov radiation (VCR) in a dispersive
nontransparent dielectric air-like medium both below and above the Cherenkov
threshold, in the framework of classical electrodynamics. It is shown that the
transition to the subthreshold energies leads to the destruction of
electromagnetic shock waves and to the sharp reduction of the frequency domain
where VCR is emitted. The fine wake-like structure of the Vavilov-Cherenkov
radiation survives and manifests the existence of the subthreshold radiation in
the domain of anomalous dispersion. These domains can approximately be defined
by the two phenomenological parameters of the medium, namely, the effective
frequency of oscillators and the damping describing an interaction with the
other degrees of freedom.


title: General response function for interacting quantum liquids

abstract:
  Linearizing the appropriate kinetic equation we derive general response
functions including selfconsistent mean fields or density functionals and
collisional dissipative contributions. The latter ones are considered in
relaxation time approximation conserving successively different balance
equations. The effect of collisions is represented by correlation functions
which are possible to calculate with the help of the finite temperature
Lindhard RPA expression. The presented results are applicable to finite
temperature response of interacting quantum systems if the quasiparticle or
mean field energy is parameterized within Skyrme - type of functionals
including density, current and energy dependencies which can be considered
alternatively as density functionals. By this way we allow to share
correlations between density functional and collisional dissipative
contributions appropriate for the special treatment. We present results for
collective modes like the plasmon in plasma systems and the giant resonance in
nuclei. The collisions lead in general to an enhanced damping of collective
modes. If the collision frequency is close to the frequency of the collective
mode, resonance occurs and the collective mode is enhanced showing a
collisional narrowing.

categories: nucl-th cond-mat.str-el physics.plasm-ph quant-ph


title: Damping of IVGDR - Fermi-liquid or Fermi-gas ?

abstract:
  Collisional relaxation rates of collective modes in nuclei are calculated
using the Levinson equation for the reduced density matrix with a memory
dependent collision term. Linearizing the collision integral two contribution
have to be distinguished, the one from the quasiparticle energy and the one
from occupation factors. The first one yields the known Landau formula of zero
sound damping and the second one leads to the Fermi gas model of Ref.1 with the
additional factor 3 in front of the frequencies. Adding both contribution we
obtain a final relaxation rate for the Fermi liquid model. Calculations of the
temperature dependence of the damping rates and of the shape evolution of IVGDR
are in good agreement with the experiment and show only minor differences
between both models.


title: ISGDR- bulk or surface mode ?

abstract:
  A polarization and response function for finite systems and temperatures is
derived from linearizing the Vlasov equation. Besides the Lindhard response
function in local density approximation we obtain an additional contribution
due to the surface. This formula is applied to isoscalar giant resonances which
we consider as next harmonics to the basic dipole mode. The spurious center of
mass motion is subtracted within the polarization. The results based on simple
Fermi liquid considerations are in reasonable agreement with experimental data.


title:
Reply to the comment on $\Delta$I=4 bifurcation in ground rotational
  bands of even-even nuclei and the interacting boson model

abstract:
  This is the reply to the comment of Kuyucak and Stuchbery on our paper
published in Phys. Rev. Lett. 79 (1997) 2006.


title: Nonlinear Effects in Nuclear Cluster Problem

abstract:
  Some nonlinear aspects of a cluster phenomenon in nuclei are considered using
of cubic Nonlinear Schroedinger Equation and Korteveg de Vries Equation. We
discuss the following possible nonlinear effects: i) the decribing clusters as
solitons; ii) an anomalous large angle scattering of $\alpha$-particles by
light and intermediate nuclei; iii) stable vortical objects; iv) and dynamical
clusterization in the presence of instability.


title: Probing the width of compound states with rotational gamma rays

abstract:
  The intrinsic width of (multiparticle-multihole) compound states is an
elusive quantity, of difficult direct access, as it is masked by damping
mechanisms which control the collective response of nuclei. Through microscopic
cranked shell model calculations, it is found that the strength function
associated with two-dimensional gamma-coincidence spectra arising from
rotational transitions between states lying at energies >1 MeV above the yrast
line, exhibits a two-component structure controlled by the rotational (wide
component) and compound (narrow component) damping width. This last component
is found to be directly related to the width of the multiparticle-multihole
autocorrelation function.


title: A Multi-Phase Transport model for nuclear collisions at RHIC

abstract:
  To study heavy ion collisions at energies available from the Relativistic
Heavy Ion Collider, we have developed a multi-phase transport model that
includes both initial partonic and final hadronic interactions. Specifically,
the parton cascade model ZPC, which uses as input the parton distribution from
the HIJING model, is extended to include the quark-gluon to hadronic matter
transition and also final-state hadronic interactions based on the ART model.
Predictions of the model for central Au on Au collisions at RHIC are reported.


title: Nonlinear waves of nuclear density

abstract:
  Nonlinear excitations of nuclear density are considered in the framework of
semiclassical nonlinear nuclear hydrodynamics. Possible types of stationary
nonlinear waves in nuclear media are analysed using Nonlinear Schroedinger
equation of fifth order and classified using a simple mechanical picture. It is
shown that a rich spectrum of nonlinear oscillations in one-dimensional nuclear
medium exist.


title: Lambda-proton correlations in relativistic heavy ion collisions

abstract:
  The prospect of using lambda-proton correlations to extract source sizes in
relativistic heavy ion collisions is investigated. It is found that the strong
interaction induces a large peak in the correlation function that provides more
sensitive source size measurements than two-proton correlations under some
circumstances. The prospect of using lambda-proton correlations to measure the
time lag between lambda and proton emissions is also studied.


title: Photoproduction of Hybrid Mesons

abstract:
  In this contribution I discuss prospects for photoproducing hybrid mesons at
CEBAF, based on recent model results and experimental indications of possible
hybrids. One excellent opportunity appears to be a search for the I=1, JPC=2+-,
neutral "(b2)o" hybrid in (a2 pi)o through diffractive photoproduction. Other
notable possibilities accessible through pi+ or pio exchange photoproduction
are I=1, JPC=1-+, charged "pi1+" in f1 pi+, (b1 pi)+ and (rho pi)+; piJ(1770)+
in f2 pi+ and (b1 pi)+; pi(1800)+ in f0 pi+, f2 pi+, omega rho+ and (rho pi)+;
a1 in f1 pi+ and f2 pi+; and omega in (rho pi)o, omega eta and (K1 K)o.


title: Quarkonium Formation Time in a Model-Independent Approach

abstract:
  We use dispersion relations to reconstruct, in a model-independent way, the
formation dynamics of heavy quarkonium from the experimental data on e+ e-
annihilation to Q-bar Q. We extract a distribution of formation times with a
mean value for the J/psi, tau{J/psi} = 0.44 fm; and for the Upsilon,
tau{Upsilon} = 0.32 fm. The corresponding widths of these distributions are
given by Delta-tau{J/psi} = 0.31 fm and Delta-tau{Upsilon} = 0.28 fm. This
information can be used as an input in modeling of heavy quarkonium production
on nuclear targets.


title: Global features of proton-neutron interactions and symmetry energy

abstract:
  We study global features of proton-neutron (p-n) interactions and symmetry
energy over a wide range of nuclei, using a schematic model interaction with
four forces proposed recently.
  Calculations are performed by the BCS approximation in N,Z=20-50 and
N,Z=50-82 regions. The experimental double differences of binding energies and
symmetry energy are reproduced quite well.
  It is shown that the isoscalar p-n interactions with all J are indispensable
for explaining the binding energies of not only
  $N\approx Z$ but also N>Z nuclei in the A=40-160 region.


title: Bonn Potential and Shell-Model Calculations for N=126 Isotones

abstract:
  We have performed shell-model calculations for the N=126 isotones 210Po,
211At, and 212Rn using a realistic effective interaction derived from the Bonn
A nucleon-nucleon potential by means of a G-matrix folded-diagram method. The
calculted binding energies, energy spectra and electromagnetic properties show
remarkably good agreement with the experimental data. The results of this paper
complement those of our previous study on neutron hole Pb isotopes, confirming
that realistic effective interactions are now able to reproduce with
quantitative accuracy the spectroscopic properties of complex nuclei.


title: Nuclear currents based on the integral form of the continuity equation

abstract:
  We present an approach to obtain new forms of the nuclear electromagnetic
current, which is based on an integral form of the continuity equation. The
procedure can be used to restore current conservation in model calculations in
which the continuity equation is not verified. Besides, it provides, as a
particular result, the so-called Siegert's form of the nuclear current, first
obtained by Friar and Fallieros by extending Siegert's theorem to arbitrary
values of the momentum transfer. The new currents are explicitly conserved and
permit a straightforward analysis of their behavior at both low and high
momentum transfers. The results are illustrated with a simple nuclear model
which includes a harmonic oscillator mean potential.


title: Hydrodynamic simulation of elliptic flow

abstract:
  We use a hydrodynamic model to study the space-time evolution transverse to
the beam direction in ultrarelativistic heavy-ion collisions with nonzero
impact parameters. We focus on the influence of early pressure on the
development of radial and elliptic flow. We show that at high energies elliptic
flow is generated only during the initial stages of the expansion while radial
flow continues to grow until freeze-out. Quantitative comparisons with SPS data
from semiperipheral Pb+Pb collisions suggest the applicability of
hydrodynamical concepts already $\approx$ 1 fm/c after impact.


title:
Strangeness Enhancement in Heavy Ion Collisions - Evidence for
  Quark-Gluon-Matter ?

abstract:
  The centrality dependence of (multi-)strange hadron abundances is studied for
Pb(158 AGeV)Pb reactions and compared to p(158 GeV)Pb collisions. The
microscopic transport model UrQMD is used for this analysis. The predicted
Lambda/pi-, Xi-/pi- and Omega-/pi- ratios are enhanced due to rescattering in
central Pb-Pb collisions as compared to peripheral Pb-Pb or p-Pb collisions. A
reduction of the constituent quark masses to the current quark masses m_s \sim
230 MeV, m_q \sim 10 MeV, as motivated by chiral symmetry restoration, enhances
the hyperon yields to the experimentally observed high values. Similar results
are obtained by an ad hoc overall increase of the color electric field strength
(effective string tension of kappa=3 GeV/fm). The enhancement depends strongly
on the kinematical cuts. The maximum enhancement is predicted around
midrapidity. For Lambda's, strangeness suppression is predicted at
projectile/target rapidity. For Omega's, the predicted enhancement can be as
large as one order of magnitude. Comparisons of Pb-Pb data to proton induced
asymmetric (p-A) collisions are hampered due to the predicted strong asymmetry
in the various rapidity distributions of the different (strange) particle
species. In p-Pb collisions, strangeness is locally (in rapidity) not
conserved. The present comparison to the data of the WA97 and NA49
collaborations clearly supports the suggestion that conventional (free)
hadronic scenarios are unable to describe the observed high (anti-)hyperon
yields in central collisions. The doubling of the strangeness to nonstrange
suppression factor, gamma_s \approx 0.65, might be interpreted as a signal of a
phase of nearly massless particles.


title: Pair creation: back-reactions and damping

abstract:
  We solve the quantum Vlasov equation for fermions and bosons, incorporating
spontaneous pair creation in the presence of back-reactions and collisions.
Pair creation is initiated by an external impulse field and the source term is
non-Markovian. A simultaneous solution of Maxwell's equation in the presence of
feedback yields an internal current and electric field that exhibit plasma
oscillations with a period tau_pl. Allowing for collisions, these oscillations
are damped on a time-scale, tau_r, determined by the collision frequency.
Plasma oscillations cannot affect the early stages of the formation of a
quark-gluon plasma unless tau_r >> tau_pl and tau_pl approx. 1/Lambda_QCD
approx 1 fm/c.


title: On Tamm's problem in the Vavilov-Cherenkov radiation theory

abstract:
  We analyse the well-known Tamm problem treating the charge motion on a finite
space interval with the velocity exceeding light velocity in medium. By
comparing Tamm's formulae with the exact ones we prove that former do not
properly describe Cherenkov radiation terms. We also investigate Tamm's formula
cos(theta)=1/(beta n) defining the position of maximum of the field strengths
Fourier components for the infinite uniform motion of a charge. Numerical
analysis of the Fourier components of field strengths shows that they have a
pronounced maximum at cos(theta)=1/(beta n) only for the charge motion on the
infinitely small interval. As the latter grows, many maxima appear. For the
charge motion on an infinite interval there is infinite number of maxima of the
same amplitude. The quantum analysis of Tamm's formula leads to the same
results.


title:
Inclusive $K^+$ and exclusive $K^+Y$ photoproduction on the deuteron:
  $\Lambda$- and $\Sigma$-threshold phenomena

abstract:
  Inclusive $K^+$ and exclusive $K^+Y$ photoproduction on the deuteron are
investigated theoretically. Modern hyperon-nucleon forces and a recently
updated kaon photoproduction operator for the $\gamma +N\to K^++Y$ process are
used. Sizable effects of the hyperon-nucleon final state interaction are found
near the $K^+\Lambda N$ and $K^+\Sigma N$ thresholds in the inclusive reaction.
Angular distributions for the exclusive process show clear $YN$ final state
interaction effects in certain kinematic regions. Precise data especially for
the inclusive process around the $K^+\Sigma N$ threshold would help to clarify
the strength and property of the $\Lambda N-\Sigma N$ interaction.


title:
Direct Test of the Scalar-Vector Lorentz Structure of the Nucleon- and
  Antinucleon-Nucleus Potential

abstract:
  Quantum Hadrodynamics in mean field approximation describes the effective
nucleon-nucleus potential (about -50 MeV deep) as resulting from a strong
repulsive vector (about 400 MeV) and a strong attractive scalar (about -450
MeV) contribution. This scalar-vector Lorentz structure implies a significant
lowering of the threshold for $p\bar{p}$ photoproduction on a nucleus by about
850 MeV as compared to the free case since charge conjugation reverses the sign
of the vector potential contribution in the equation of motion for the
$\bar{p}$ states. It also implies a certain size of the photon induced
$p\bar{p}$ pair creation cross section near threshold which is calculated for a
target nucleus $^{208}$Pb. We also indicate a measurable second signature of
the $p\bar{p}$ photoproduction process by estimating the increased cross
section for emission of charged pions as a consequence of $\bar{p}$
annihilation within the nucleus.


title: Kinetic-theory approach to low-energy collective modes in nuclei

abstract:
  Two different solutions of the linearized Vlasov equation for finite systems,
characterized by fixed and moving-surface boundary conditions, are discussed in
a unified perspective. A condition determining the eigenfrequencies of
collective nuclear oscillations, that can be obtained from the moving-surface
solution, is studied for isoscalar vibrations of lowest multipolarity. Analytic
expressions for the friction and mass parameters related to the low-enegy
surface excitations are derived and their value is compared to values given by
other models. Both similarities and differences are found with respect to the
other approaches, however the close agreement obtained in many cases with one
of the other models suggests that, in spite of some important differences, the
two approaches are substantially equivalent. The formalism based on the Vlasov
equation is more transparent since it leads to analytical expressions that can
be a basis for further improvement of the model.


title:
Residual correlation in two-proton interferometry from lambda-proton
  strong interactions

abstract:
  We investigate the residual effect of lambda-proton strong interactions in pp
correlations with one proton from lambda decays. It is found that the residual
correlation is about 10% of the lambda-proton correlation strength, and has a
broad distribution centered around q~40 MeV/c. The residual correlation cannot
explain the observed structure on the tail of the recently measured pp
correlation function in central Pb+Pb collisions by NA49 at the SPS.


title: Enhanced pion production in DCC dynamics

abstract:
  In order to elucidate the enhancement of pion production that may occur
during dynamical scenarios of interest in connection with disoriented chiral
condensates, we study the evolution of boson modes whose frequencies have a
given arbitrary time dependence. The quantum-field treatment yields expressions
for the time dependence of observables that depend only on the initial state
and specific state-independent enhancement coefficients which can be obtained
from the given evolution of the frequency. It is shown how these coefficients
also can be obtained within an entirely classical framework by judicious usage
of the dependence of the resulting enhancement on the phase of the initial
state. Illustrative application is made for frequency evolutions obtained from
idealized simulations of high-energy heavy-ion collisions and it is shown how
the non-equilibrium evolution of the order parameter may lead to significant
enhancements in the final pion spectra.


title: Charmonium dissociation in hadronic matter

abstract:
  Production of J/$\psi$ from nucleus-nucleus reactions depends sensitively on
the dissociation cross section with light hadrons. Effective lagrangian methods
are used to describe the hadronic degrees of freedom, including strangeness and
charm. Cross sections with pions, rho mesons, kaons and nucleons having
magnitudes 4--8 mb are found, and with steep thresholds. This, folded with
thermal momentum distributions for the scattering partners, suggests a mean
dissociation lifetime $\simeq$ 20 fm/c. Therefore, the ``abnormal'' J/$\psi$
suppression seen in recent Pb+Pb experiments seems to owe to expected hadron
kinetics.


title: The QGP-Stall or Not ?

abstract:
  In 1996, D.H. Rischke and M. Gyulassy proposed to use the time-delay signal
in Bose-Einstein correlations (BEC) as a signature for the possible formation
of a quark-gluon plasma (QGP) in relativistic heavy-ion collisions. In
particular, they suggested to measure the ratio of the transversal
interferometry radii, $R_{out}/R_{side}$, which can be obtained by fitting
experimental BEC data with a parametrization introduced by G. Bertsch et al. in
1988. The transverse radius parameter $R_{out}$ has compared to the transverse
radius parameter $R_{side}$ an additional temporal dependence which should be
sensitive to a prolonged lifetime of a fireball, in case a QGP was formed in a
relativistic heavy-ion collision. This latter phenomenon is known under the
term ``QGP stall''. In the following, I shall explain why I believe that the
time-delay signal in Bose-Einstein correlations is not a good signature for the
possible formation of a QGP.


title: Coulomb Distortion Effects for (e,e'p) Reactions at High Electron Energy

abstract:
  We report a significant improvement of an approximate method of including
electron Coulomb distortion in electron induced reactions at momentum transfers
greater than the inverse of the size of the target nucleus. In particular, we
have found a new parametrization for the elastic electron scattering phase
shifts that works well at all electron energies greater than 300 $MeV$. As an
illustration, we apply the improved approximation to the $(e,e'p)$ reaction
from medium and heavy nuclei. We use a relativistic ``single particle'' model
for $(e,e'p)$ as as applied to $^{208}Pb(e,e'p)$ and to recently measured data
at CEBAF on $^{16}O(e,e'p)$ to investigate Coulomb distortion effects while
examining the physics of the reaction.


title: Light-Front Dynamics

abstract:
  The wave function in relativity is defined, in four-dimensional space, on a
space-like three-dimensional plane. The plane, most close to the time-like
region, is the light-front plane $ct+z=0$. Corresponding dynamical approach -
the light-front dynamics - has considerable advantages. We describe, in a
field-theoretical framework, the construction of light-front dynamics and
illustrate it by some examples.


title:
Transitional Lu and Spherical Ta Ground-State Proton Emitters in the
  Relativistic Hartree-Bogoliubov model

abstract:
  Properties of transitional Lu and spherical Ta ground-state proton emitters
are calculated with the Relativistic Hartree Bogoliubov (RHB) model. The NL3
effective interaction is used in the mean-field Lagrangian, and pairing
correlations are described by the pairing part of the finite range Gogny
interaction D1S. Proton separation energies, ground-state quadrupole
deformations, single-particle orbitals occupied by the odd valence proton, and
the corresponding spectroscopic factors are compared with recent experimental
data, and with results of the macroscopic-microscopic mass model.


title: Color plasma oscillation in strangelets

abstract:
  The dispersion relation and damping rate of longitudinal color plasmons in
finite strange quark matter (strangelets) are evaluated in the limits of weak
coupling, low temperature, and long wavelength. The property of the QCD vacuum
surrounding a strangelet makes the frequency of the plasmons nearly the same as
the color plasma frequency of bulk matter. The plasmons are damped by their
coupling with individual excitations of particle-hole pairs of quarks, of which
the energy levels are discretized by the boundary. For strangelets of
macroscopic size, the lifetime of the plasmons is found to be proportional to
the size, as in the case of the usual plasma oscillations in metal
nanoparticles.


title: Baryon Fluctuations in High Energy Nuclear Collisions

abstract:
  We propose that dramatic changes in the variances and covariance of protons
and antiprotons can result if baryons approach chemical equilibrium in nuclear
collisions at RHIC. To explore how equilibration alters these fluctuations, we
formulate both equilibrium and nonequilibrium hadrochemical descriptions of
baryon evolution. Contributions to fluctuations from impact parameter averaging
and finite acceptance in nuclear collisions are numerically simulated.


title: Gaps and Critical Temperature for Color Superconductivity

abstract:
  Because of a logarithmic enhancement from soft, collinear magnetic gluons, in
dense quark matter the gap for a color superconducting condensate with spin
zero depends upon the QCD coupling constant g not as exp(-1/g^2), like in BCS
theory, but as exp(-1/g). In weak coupling, the ratio of the transition
temperature to the spin-zero gap at zero temperature is the same as in BCS
theory. We classify the gaps with spin one, and find that they are of the same
order in g as the spin-zero gap.


title: n+p -> d+gamma for Big-Bang Nucleosynthesis

abstract:
  The cross section for n+p -> d+gamma is calculated at energies relevant to
big bang nucleosynthesis using the recently developed effective field theory
that describes the two-nucleon sector. The E1 amplitude is computed up to NNNLO
and depends only upon nucleon-nucleon phase shift data. In contrast, the M1
contribution is computed up to NLO, and the four-nucleon-one-magnetic-photon
counterterm that enters is determined by the cross section for cold neutron
capture. The uncertainty in the calculation for nucleon energies up to E ~ 1
MeV is estimated to be < 4%.


title:
Quark distrbutions in the nucleon based on a relativistic 3-body
  approach to the NJL model

abstract:
  Quark light cone momentum distributions in the nucleon are calculated in a
relativistic 3-body approach to the NJL model by using a simple 'static
approximation' for the Faddeev kernel. A method is presented which
automatically satisfies the number and momentum sum rules, even in the
regularized theory. In order to assess the sensitivity to the regularization
scheme, two schemes which can be formulated in terms of light cone variables
are discussed. The effects of the (composite) pion cloud are taken into account
in a convolution approach, and the violation of the Gottfried sum rule is
discussed. After performing the Q^2 evolution, the resulting distributions are
compared to the empirical ones.


title:
The State Dependence Calculation of Three-body Cluster Energy for
  Nuclear Matter

abstract:
  It is shown that the method of lowest order contrained variational (LOCV)
which is based on the cluster expansion theory is a reliable many-body
technique to calculate the nuclear matter equation of states. In this respect
the state-dependence correlation functions and effective interactions which
have been produce by LOCV calculation with the Reid Soft Core and $\Delta
$-Reid interactions are used to estimate the size of higher order cluster terms
such as the effect of three body cluster energy in nuclear matter. We find that
the three-body cluster energy is less than 1 MeV beyond the nuclear matter
saturation density and it has weaker density dependence than our previous
calculation with the state-averaged coorrelation functions and effective
interactions. Finally, we conclude that the LOCV method is good enough to
calculate other propertiesn of quantal fluids.


title: Three dimensional relativistic hydrodynamical model for QGP gas

abstract:
  We numerically solve fully (3+1)-dimensional relativistic hydrodynamical
equation coupled with the baryon number conservation law without spatial
symmetry. We discuss the effect of transverse expansion based on the deviation
our numerical result from Bjorken's scaling solution. We analyze the space-time
evolution of the QGP gas in the case of non cylindrical initial conditions.


title:
Analyses of collective flow and space-time evolution based on
  relativistic hydrodynamical model

abstract:
  We numerically solve fully (3+1)-dimensional relativistic hydrodynamical
equation with the baryon number conservation law. For realistic initial
conditions we adopt the results from the event generator (URASiMA). Using this
model we discuss collective flow.


title: Isoscalar Hamiltonians for light atomic nuclei

abstract:
  The charge-dependent realistic nuclear Hamiltonian for a nucleus, composed of
neutrons and protons, can be successfully approximated by a charge-independent
one. The parameters of such a Hamiltonian, i.e., the nucleon mass and the NN
potential, depend upon the mass number A, charge Z and isospin quantum number T
of state of the studied nucleus.


title: Space-time analysis: HBT at SPS and RHIC

abstract:
  In this review talk, I first summarize the conclusions which can be drawn
from a particle interferometric analysis of CERN SPS data and then I address
related questions which are relevant for the upcoming experiments at RHIC.


title: Shell-model calculations of neutrino scattering from 12C

abstract:
  Neutrino reaction cross-sections, $(\nu_\mu,\mu^-)$, $(\nu_e,e^-)$,
$\mu$-capture and photoabsorption rates on $^{12}$C are computed within a
large-basis shell-model framework, which included excitations up to
$4\hbar\omega$. When ground-state correlations are included with an open
$p$-shell the predictions of the calculations are in reasonable agreement with
most of the experimental results for these reactions. Woods-Saxon radial wave
functions are used, with their asymptotic forms matched to the experimental
separation energies for bound states, and matched to a binding energy of 0.01
MeV for unbound states. For comparison purposes, some results are given for
harmonic oscillator radial functions. Closest agreement between theory and
experiment is achieved with unrestricted shell-model configurations and
Woods-Saxon radial functions. We obtain for the neutrino-absorption inclusive
cross sections: $\bar{\sigma} = 13.8 \times 10^{-40}$ cm$^2$ for the
$(\nu_{\mu},\mu^{-})$ decay-in-flight flux in agreement with the LSND datum of
$(12.4 \pm 1.8) \times 10^{-40}$ cm$^2$; and $\bar{\sigma} = 12.5 \times
10^{-42}$ cm$^2$ for the $(\nu_{e},e^{-})$ decay-at-rest flux, less than the
experimental result of $(14.4 \pm 1.2) \times 10^{-42}$ cm$^2$.


title:
Exact Treatment of the Pauli Exclusion Operator in Nuclear Matter
  Calculation

abstract:
  Exact expressions of the Pauli exclusion operator Q in the nuclear matter
calculation are presented in detail. Exact formulae are also given for the
calculations of the single-particle-potential energy and the binding energy per
nucleon with the exact Q operator. Numerical calculations of the G matrix in
the lowest-order Brueckner theory are carried out to check the reliability of
the standard angle-average approximation for the
  Q operator by employing the Bonn B and C NN potentials. It is observed that
the exact treatment of the operator Q brings about non-negligible and
attractive contributions to the binding energy.


title: Dynamical simulation of DCC formation in Bjorken rods

abstract:
  Using a semi-classical treatment of the linear sigma model, we simulate the
dynamical evolution of an initially hot cylindrical rod endowed with a
longitudinal Bjorken scaling expansion (a ``Bjorken rod''). The field equation
is propagated until full decoupling has occurred and the asymptotic many-body
state of free pions is then obtained by a suitable Fourier decomposition of the
field and a subsequent stochastic determination of the number of quanta in each
elementary mode. The resulting transverse pion spectrum exhibits visible
enhancements below 200 MeV due to the parametric amplification caused by the
oscillatory relaxation of the chiral order parameter. Ensembles of such final
states are subjected to various event-by-event analyses. The factorial moments
of the multiplicity distribution suggest that the soft pions are
non-statistical. Furthermore, their emission patterns exhibit azimuthal
correlations that have a bearing on the domain size in the source. Finally, the
distribution of the neutral pion fraction shows a significant broadening for
the soft pions which grows steadily as the number of azimuthal segments is
increased. All of these features are indicative of disoriented chiral
condensates and it may be interesting to apply similar analyses to actual data
from high-energy nuclear collision experiments.


title: $K^-$ and $\bar p$ deeply bound atomic states

abstract:
  The strongly absorptive optical potentials $V_{{\rm opt}}$ which have been
deduced from the strong-interaction level shifts and widths in X-ray spectra of
$K^-$ and $\bar p$ atoms produce effective repulsion leading to substantial
suppression of the {\it atomic} wave functions within the nucleus. The width of
atomic levels then saturates as function of the strength of Im $V_{{\rm opt}}$.
We find that `deeply bound' atomic states, which are inaccessible in the atomic
cascade process, are generally narrow, due to this mechanism, over the entire
periodic table %reaching values of $\Gamma_{K^-} \sim 1.7$ MeV and
%$\Gamma_{\bar p} \sim 1.9$ MeV for the $1s$ state in Pb, and should be
reasonably well resolved. These predictions are insensitive to $V_{{\rm opt}}$,
provided it was fitted to the observed X-ray spectra. In contrast, the {\it
nuclear} states bound by $V_{{\rm opt}}$ are very broad and their spectrum
depends sensitively on details of $V_{{\rm opt}}$. We discuss production
reactions for $K^-$ atomic states using slow $K^-$ mesons from the decay of the
$\phi$(1020) vector meson, and the ($\bar p, p$) reaction for $\bar p$ atomic
states. Rough cross-section estimates are given.


title:
Relativistic quasipotential equations with u-channel exchange
  interactions

abstract:
  Various quasipotential two-body scattering equations are studied at the
one-loop level for the case of $t$- and $u$-channel exchange potentials. We
find that the quasipotential equations devised to satisfy the one-body limit
for the $t$-channel exchange potential can be in large disagreement with the
field-theoretical prediction in the case of $u$-channel exchange interactions.
Within the spectator model, the description of the $u$-channel case improves if
another choice of the spectator particle is made. Since the appropriate choice
of the spectator depends strongly on the type of interaction used, one faces a
problem when both types of interaction are contained in the potential.
Equal-time formulations are presented, which, in the light-heavy particle
system corresponding to the mass situation of the $\pi N$ system, approximate
in a reasonable way the field-theoretical result for both types of
interactions.


title:
Few-nucleon systems in translationally invariant harmonic oscillator
  basis

abstract:
  We present a translationally invariant formulation of the no-core shell model
approach for few-nucleon systems. We discuss a general method of
antisymmetrization of the harmonic-oscillator basis depending on Jacobi
coordinates. The use of a translationally invariant basis allows us to employ
larger model spaces than in traditional shell-model calculations. Moreover, in
addition to two-body effective interactions, three- or higher-body effective
interactions as well as real three-body interactions can be utilized. In the
present study we apply the formalism to solve three and four nucleon systems
interacting by the CD-Bonn nucleon-nucleon potential. Results of ground-state
as well as excited-state energies, rms radii and magnetic moments are
discussed. In addition, we compare charge form factor results obtained using
the CD-Bonn and Argonne V8' NN potentials.


title: Fractal Structure of Random Matrices

abstract:
  A multifractal analysis is performed on the universality classes of random
matrices and the transition ones.Our results indicate that the eigenvector
probability distribution is a linear sum of two chi-squared distribution
throughout the transition between the universality ensembles of random matrix
theory and Poisson .


title: Generalized polarizabilities and electroexcitation of the nucleon

abstract:
  Generalized nucleon polarizabilities for virtual photons can be defined in
terms of electroproduction cross sections as function of the 4-momentum
transfer $Q^2$. In particular, the sum of the generalized electric and magnetic
polarizabilities $\Sigma=\alpha+\beta$ and the spin polarizability $\gamma$ can
be expressed by virtual photon absorption cross sections integrated over the
excitation energy. These quantities have been calculated within the framework
of the recently developed unitary isobar model for pion photo- and
electroproduction on the proton, which describes the available experimental
data up to an excitation energy of about 1 GeV. Our results have been compared
to the predictions of chiral perturbation theory.


title:
Coherent pion electroproduction on the deuteron in the $\Delta(1232)$
  resonance region

abstract:
  Coherent pion electroproduction on the deuteron is studied in the
$\Delta(1232)$ resonance region in the impulse approximation, i.e., neglecting
pion rescattering and two-body effects. The elementary reaction on the nucleon
is described in the framework of an effective Lagrangian approach including the
dominant $P_{33}(1232)$ resonance and the usual background terms of the Born
contributions for $\pi^0$ production. We have studied the influence of these
different contributions on the various structure functions which determine the
unpolarized exclusive differential cross section in a variety of kinematic
regions.


title: Theory of doorway states for one-nucleon transfer reactions

abstract:
  The doorway states under consideration are eigenstates of the hamiltonian
which is the sum of the kinetic energy and the infinite energy limit of the
single-particle mass operator. Only Hartree diagrams with the free-space
nucleon-nucleon forces contribute to this limit, and therefore the observed
doorway state energies carry an important information about both the nuclear
structure and the free-space nucleon-nucleon interaction.


title: On the current status of OZI violation in ${\pi}N$ and pp reactions

abstract:
  The available data on $\omega$ and $\phi$ production from $\pi N$ and $pp$
collisions are reanalyzed with respect to an OZI rule violation on the basis of
transition matrix elements. The data are found to be compatible with a constant
ratio $R$ up to excess energies $\epsilon{\approx}300$ MeV, however, the ratio
$R$ deviates substantially from the SU(3) prediction based on the present
knowledge of the $\phi-\omega$ mixing angle.


title: Primordial hadrosynthesis in the Little Bang

abstract:
  The present status of soft hadron production in high energy heavy-ion
collisions is summarized. In spite of strong evidence for extensive dynamical
evolution and collective expansion of the fireball before freeze-out I argue
that its chemical composition is hardly changed by hadronic final state
interactions. The measured hadron yields thus reflect the primordial conditions
at hadronization. The observed production pattern is consistent with
statistical hadronization at the Hagedorn temperature from a state of
uncorrelated, color deconfined quarks and antiquarks, but requires non-trivial
chemical evolution of the fireball in a prehadronic (presumably QGP) stage
before hadron formation.


title:
Microscopic study of freeze-out in relativistic heavy ion collisions at
  SPS energies

abstract:
  The freeze-out conditions in the light (S+S) and heavy (Pb+Pb) colliding
systems of heavy nuclei at 160 AGeV/$c$ are analyzed within the microscopic
Quark Gluon String Model (QGSM). We found that even for the most heavy systems
particle emission takes place from the whole space-time domain available for
the system evolution, but not from the thin ''freeze-out hypersurface", adopted
in fluid dynamical models. Pions are continuously emitted from the whole volume
of the reaction and reflect the main trends of the system evolution. Nucleons
in Pb+Pb collisions initially come from the surface region. For both systems
there is a separation of the elastic and inelastic freeze-out. The mesons with
large transverse momenta, $p_t$, are predominantly produced at the early stages
of the reaction. The low $p_t$-component is populated by mesons coming mainly
from the decay of resonances. This explains naturally the decreasing source
sizes with increasing $p_t$, observed in HBT interferometry. Comparison with
S+S and Au+Au systems at 11.6 AGeV/$c$ is also presented.


title:
Equilibrium and non-equilibrium effects in relativistic heavy ion
  collisions

abstract:
  The hypothesis of local equilibrium (LE) in relativistic heavy ion collisions
at energies from AGS to RHIC is checked in the microscopic transport model. We
find that kinetic, thermal, and chemical equilibration of the expanding
hadronic matter is nearly reached in central collisions at AGS energy for $t
\geq 10$ fm/$c$ in a central cell. At these times the equation of state may be
approximated by a simple dependence $P \cong (0.12-0.15) \epsilon$. Increasing
deviations of the yields and the energy spectra of hadrons from statistical
model values are observed for increasing bombarding energies. The origin of
these deviations is traced to the irreversible multiparticle decays of strings
and many-body $(N \geq 3)$ decays of resonances. The violations of LE indicate
that the matter in the cell reaches a steady state instead of idealized
equilibrium. The entropy density in the cell is only about 6% smaller than that
of the equilibrium state.


title: Distribution of matrix elements of random operators

abstract:
  It is shown that an operator can be defined in the abstract space of random
matrices ensembles whose matrix elements statistical distribution simulates the
behavior of the distribution found in real physical systems. It is found that
the key quantity that determines these distribution is the commutator of the
operator with the Hamiltonian. Application to symmetry breaking in quantum
many-body systems is discussed.


title:
Baryonic contributions to e+e- yields in a hydrodynamic model of Pb+Au
  collisions at the SPS

abstract:
  We analyze e+e- yields from matter containing baryons in addition to mesons
using a hydrodynamic approach to describe Pb+Au collisions at 158 A GeV/c. We
use two distinctly different e+e- production rates to provide contrast.
Although the presence of baryons leads to significant enhancement of e+e-
emission relative to that from mesons-only matter, the calculated results fall
below the data in the range 400 < M/MeV < 600. The calculated results are,
however, only 1.3-1.5 standard deviations below the data, which may not be
statistically significant.


title: Symmetry-Projected Hartree-Fock-Bogoliubov Equations

abstract:
  Symmetry-projected Hartree-Fock-Bogoliubov (HFB) equations are derived using
the variational ansatz for the generalized one-body density-matrix in the
Valatin form. It is shown that the projected-energy functional can be
completely expressed in terms of the HFB density-matrix and the pairing-tensor.
The variation of this projected-energy is shown to result in HFB equations with
modified expressions for the pairing-potential and the Hartree-Fock field. The
expressions for these quantities are explicitly derived for the case of
particle number-projection. The numerical applicability of this projection
method is studied in an exactly soluble model of a deformed single-j shell.


title: Reconstruction of the Proton Source in Relativistic Heavy Ion Collisions

abstract:
  We describe a direct method to reconstruct the transverse proton source
formed in a relativistic heavy ion collision, making use of experimentally
measured proton and deuteron spectra and assuming that deuterons are formed via
two-nucleon coalescence. We show that an ambiguity with respect to the source
temperature still persists and we indicate a possible solution to the problem.


title: What do mesons have to do with nuclear structure?

abstract:
  The theory of nuclear structure (binding, low energy spectra, transitions,
etc.) depends on nucleon-nucleon (NN) interactions. The meson theory of NN
interactions has predictive power for NN scattering, and partial success when
applied to the theory of nuclear structure. Is it possible to test this
theoretical picture -- by direct experimental interaction with mesons in
nuclei? Some experimental searches for the `pion excess' in nuclei have
ambiguous results. How sensitive are such experiments to the mesonic aspects of
nuclear structure? These questions are addressed in this talk. More details and
references are given in Reference [1].


title:
An investigation of nuclear collisions with a momentum-dependent Lattice
  Hamiltonian model

abstract:
  We formulate a Lattice Hamiltonian approach for the modeling of intermediate
energy heavy ion collisions. After verifying stationary ground state solutions,
we implement this in a calculation of nuclear stopping power and compare our
results with experimental data. Our findings support a relatively soft nuclear
equation of state, with a momentum-dependent self-consistent mean field.


title: The Anapole Form Factor of the Deuteron

abstract:
  We find the leading order result for the anapole form factor of the deuteron
using effective field theory. The momentum dependence of the anapole form
factor is different from that of the matrix element of the strange currents in
the deuteron, which may provide a way for disentangling these two competing
effects when analyzing parity violating electron-deuteron scattering
experiments. We give closed form expressions for both the form factor and
integrals often encountered in the NN effective field theory.


title:
Coulomb distortion of pi+/pi- as a tool to determine the fireball radius
  in central high energy heavy ion collisions

abstract:
  We compute the Coulomb distortion produced by an expanding and highly charged
fireball on the spectra of low transverse momenta and mid rapidity pions
produced in central high energy heavy ion collisions. We compare to data on
Au+Au at 11.6A GeV from E866 at the BNL AGS and of Pb+Pb at 158A GeV from NA44
at the CERN SPS. We match the fireball expanison velocity with the average
transverse momentum of protons and find a best fit to the charged pion ratio
when the fireball radius is about 10 fm at freeze-out. This value is common to
both AGS and SPS data.


title:
Proton and deuteron distributions as signatures for collective particle
  dynamics and event shape geometries at the RHIC

abstract:
  We present predictions for the formation of (anti)nuclear bound states in
nucleus-nucleus reactions at RHIC energies. he phase space coalescence method
is used in combination with RQMD-v2.4 transport calculations to demonstrate the
relevance of particle production as well as the longitudinal and transverse
flow components. The formation of deuterons follows an approximate scaling law
proportional to the relative freeze-out densities of nucleons and produced
secondaries. For antideuterons, an additional suppression appears that is
proportional to the number of nucleons, pointing toward multiple rescattering
and absorption prior to freeze-out.


title:
An intrinsic state for an extended version of the interacting boson
  model

abstract:
  An intrinsic-state formalism for IBM-4 is presented. A basis of deformed
bosons is introduced which allows the construction of a general trial wave
function which has Wigner's spin-isospin SU(4) symmetry as a particular limit.
Intrinsic-state calculations are compared with exact ones showing good
agreement.


title: Effective Field Theory and Nuclear Mean-Field Models

abstract:
  The implications of an effective field theory (EFT) interpretation of nuclear
mean-field phenomenology are reviewed.


title: Possible Dibaryons with Strangeness s=-5

abstract:
  In the framework of $RGM$, the binding energy of the six quark system with
strangeness s=-5 is systematically investigated under the SU(3) chiral
constituent quark model. The single $\Xi^*\Omega$ channel calculation with
spins S=0 and 3 and the coupled $\Xi\Omega$ and $\Xi^*\Omega$ channel
calculation with spins S=1 and 2 are considered, respectively. The results show
following observations: In the spin=0 case, $\Xi^* \Omega$ is a bound dibaryon
with the binding energy being $80.0 \sim 92.4 MeV$. In the S=1 case,
$\Xi\Omega$ is also a bound dibaryon. Its binding energy is ranged from $26.2
MeV$ to $32.9 MeV$. In the S=2 and S=3 cases, no evidence of bound dibaryons
are found. The phase shifts and scattering lengths in the S=0 and S=1 cases are
also given.


title: Dynamics and Sizes of the Fireball at Freeze-out

abstract:
  Analyzing the m_t-spectrum and two-particle correlations of negative hadrons
from 158 AGeV/c Pb+Pb collisions at slightly forward rapidities we find a
(thermal) freeze-out temperature of about 100 MeV and transverse flow with
<v_t> approximately 0.55c. The M_t-dependence of the correlation radii prefers
a box-like transverse density profile over a Gaussian. From an analysis of the
pion phase-space density we find pion chemical potential of approximately 60
MeV at thermal freeze-out.


title: Thermodynamics of $n$-$p$ condensate in asymmetric nuclear matter

abstract:
  We study the neutron-proton pairing in nuclear matter as a function of
isospin asymmetry at finite temperatures and the saturation density using
realistic nuclear forces and Brueckner-renormalized single particle spectra.
Our computation of the thermodynamic quantities shows that while the difference
of the entropies of the superconducting and normal phases anomalously changes
its sign as a function of temperature for arbitrary asymmetry, the grand
canonical potential does not; the superconducting state is found to be stable
in the whole temperature-asymmetry plane. The pairing gap completely disappears
for density-asymmetries exceeding $\alpha_c= (n_n-n_p)/n \simeq 0.11$.


title: Quartet S Wave Neutron Deuteron Scattering in Effective Field Theory

abstract:
  The real and imaginary part of the quartet S wave phase shift in nd
scattering (^4 S_{3/2}) for centre-of-mass momenta of up to 300 MeV (E_cm
\approx 70 MeV) is presented in effective field theory, using both perturbative
pions and a theory in which pions are integrated out. As available, the
calculation agrees with both experimental data and potential model
calculations, but extends to a higher, so far untested momentum r\'egime above
the deuteron breakup point. A Lagrangean more feasible for numerical
computations is derived.


title: Saturation from nuclear pion dynamics

abstract:
  We construct an equation-of-state for nuclear matter based on the chiral
Lagrangian. The relevant scales are discussed and an effective chiral power
expansion scheme, which is constructed to work around the nuclear saturation
density, is presented. A realistic equation-of-state is obtained by adjusting
one free parameter, when the leading and subleading terms in the expansion are
included. The saturation mechanism is due to correlations induced by the
one-pion-exchange interaction. Furthermore, we find a substantial deviation
from the Fermi-gas estimate of the quark condensate in nuclear matter already
at the saturation density.


title: Lambda-Sigma^0 mixing in finite nuclei

abstract:
  Properties of hypernuclei are studied in the context of a chiral Lagrangian
which successfully describes ordinary nuclei. Lambda-Sigma^0 mixing arises from
nondiagonal vertices in flavor space induced by the vector mesons and by the
electromagnetic field. The set of Dirac equations for the coupled hyperon
system is discussed. Results are presented for energy spectra and
electromagnetic properties of hyperons in the nuclear environment. Simple
estimates suggest that flavor mixing can lead to sizable changes in the
lifetimes of Lambda hypernuclei.


title:
Low-Lying 2+ states in neutron-rich oxygen isotopes in quasiparticle
  random phase approximation

abstract:
  The properties of the low-lying, collective 2+ states in neutron-rich oxygen
isotopes are investigated in the framework of self-consistent microscopic
models with effective Skyrme interactions. In RPA the excitation energies E2+
can be well described but the transition probabilities are much too small as
compared to experiment. Pairing correlations are then accounted for by
performing quasiparticle RPA calculations. This improves considerably the
predictions of B(E2) values and it enables one to calculate more reliably the
ratios Mn/Mp of neutron-to-proton transition amplitudes. A satisfactory
agreement with the existing experimental values of Mn/Mp is obtained.


title: Quasi-Deuteron Configurations in odd-odd N=Z nuclei

abstract:
  The isovector M1 transitions between low-lying T=1 and T=0 states in odd-odd
N=Z nuclei are analyzed. Simple analytical expressions for M1 transition
strengths are derived within a single-j-shell approximation for both j=l+1/2
and j=l-1/2 cases. The large B(M1) values for the j=l+1/2 case are attributed
to quasi-deuteron configurations. The B(M1) values for the j=l-1/2 case are
found to be small due to partly cancellation of spin and orbital parts of the
M1 matrix element.


title:
Systematics of the Quadrupole-Quadrupole Interaction and Convergence
  Properties

abstract:
  Our main concern in this work is to show how higher shell admixtures affect
the spectrum of a Q.Q interaction. We first review how, in the valence space,
the familiar SU(3) result for the energy spectrum can be obtained using a
coordinate space Q.Q interaction rather than the Elliott one which is symmetric
in r and p. We then reemphasize that the Elliott spectrum goes as L(L+1) where
L is the orbital angular momentum. While in many cases this is compatible with
the rotational formula which involves I(I+1), where I is the total angular
momentum, there are cases, e.g. odd-odd nuclei, where there is disagreement.
Finally, we consider higher shell admixtures and devise a scheme so as to
obtain results, with the Q.Q interaction, which converge as the model spaces
are increased. We consider not only ground state rotational bands but also
those that involve intruder states.


title: Multiple Scattering Theory for Slow Neutrons (from thermal to ultracold)

abstract:
  The general theory of neutron scattering is presented, valid for the whole
domain of slow neutrons from thermal to ultracold. Particular attention is
given to multiple scattering which is the dominant process for ultracold
neutrons (UCN). For thermal and cold neutrons, when the multiple scattering in
the target can be neglected, the cross section is reduced to the known value. A
new expression for inelastic scattering cross section for UCN is proposed.
Dynamical processes in the target are taken into account and their influence on
inelastic scattering of UCN is analyzed.


title: Interactions of quarkonium at low energies

abstract:
  We present two examples of the short-distance QCD calculations for the
quarkonium (\Phi) interactions; 1) \pi \Phi elastic and \pi \Phi -> \pi \Phi'
cross sections, and 2) the potential between two \Phi's. The former is relevant
for the \Phi suppression in heavy ion collisions; we find that the
corresponding cross sections are very small. For the latter we derive the sum
rule which relates the strength of the potential to the energy density of the
QCD vacuum. The key starting point in both cases is that the leading operator
in the operator product expansion (OPE) for the low--energy scattering
amplitude is the trace of the QCD stress tensor whose matrix elements are
unambiguously fixed by the low energy theorem. The resonances in the two-pion
scalar channel are taken into account as a formfactor.


title: Shapes and beta decay in proton rich Ge, Se, Kr and Sr isotopes

abstract:
  We study ground states and beta decay properties of the proton rich isotope
chains Ge, Se, Kr, and Sr. We use a deformed selfconsistent HF+RPA approach
with density-dependent effective interactions of Skyrme type. We find that most
of the isotopes present two HF minima corresponding to two different shapes. In
addition to static quadrupole moments and other ground state band properties,
we present results for Gamow-Teller strength distributions, as well as for
half-lives and summed strengths. The role of deformation is particularly
emphasized.


title: Diquarks: condensation without bound states

abstract:
  We employ a bispinor gap equation to study superfluidity at nonzero chemical
potential: mu .neq. 0, in two- and three-colour QCD. The two-colour theory,
QC2D, is an excellent exemplar: the order of truncation of the quark-quark
scattering kernel: K, has no qualitative impact, which allows a straightforward
elucidation of the effects of mu when the coupling is strong. In rainbow-ladder
truncation, diquark bound states appear in the spectrum of the three-colour
theory, a defect that is eliminated by an improvement of K. The corrected gap
equation describes a superfluid phase that is semi-quantitatively similar to
that obtained using the rainbow truncation. A model study suggests that the
width of the superfluid gap and the transition point in QC2D provide reliable
quantitative estimates of those quantities in QCD.


title:
Equation of State of Hypermatter in beta Equilibrium in a Quark Model
  with Excluded Volume Correction

abstract:
  We study the effects of the finite size of the baryons on the equation of
state of homogeneous hadronic matter with hyperons. The finite extension of
hadrons is introduced in order to improve the perfomance of field theoretical
models at very high densities, simulating the short-range hard-core repulsive
part of the baryon-baryon potential. We choose the Quark Meson Coupling model
to describe the baryon dynamics because this model provides a density dependent
radius of the bag. In addition we calculate finite size corrections for the
Zimanyi-Moszkowski model in order to make a definite comparison. In both cases
finite size effects are implemented through a Van der Waals like correction in
the normalization of the baryon fields. In this approach we investigate
$\beta$-stable matter in conditions that could be found in the interior of
massive stars. We find that the excluded volume corrections contribute
significantly for densities above twice the symmetric nuclear matter saturation
density, although for the quark model the results strongly depends upon the
equilibrium conditions for the confinement volume immersed in a dense medium.


title: Hartree--Fock--Bogoliubov Approximation for Finite Systems

abstract:
  Some general features of the spectrum of the Hartree-Fock-Bogoliubov
equations are examined. Special attention is paid to the asymptotic behavior of
the single quasiparticle wave functions (s.qp.w.fs.), matter density
distribution and density of the pair condensate. It is shown that due to the
coupling between hole and particle states,the deeply bound hole states acquire
a width and have to be treated as continuum states. The proper normalization of
the s.qp.w.fs. is discussed.


title: Back-to-Back Correlations for Bosons Modified by Medium

abstract:
  Novel back-to-back correlations are shown to arise for thermal ensembles of
squeezed bosonic states associated with medium-modified mass-shifts. The
strength of these correlations could become unexpectedly large in heavy ion
collisions.


title: Last Call for RHIC Predictions

abstract:
  This paper contains the individual contributions of all speakers of the
session on 'Last Call for RHIC Predictions' at Quark Matter 99, and a summary
by the convenor.


title:
Electron and Photon induced Reactions on Nuclei in the Nucleon Resonance
  Region

abstract:
  We calculate total photon-nucleus and electron-nucleus cross sections $\gamma
A\to X$, $e A\to e^\prime X$ and several cross sections on pion and eta
production in nuclei in the energy regime between the first and the third
resonance region for photon virtualities $Q^2\le 1.0 GeV^2$ within a
semi-classical BUU transport model. In both cases we discuss the varying
influence of several medium modifications on the cross sections for different
values of Q^2.


title: Spin-Orbit-Like Terms in Semileptonic Weak Hamiltonian

abstract:
  It is shown that new spin-orbit-like terms appear in the effective
nonrelativistic weak Hamiltonian for nucleon provided that nuclear potential is
taken into account. Arguments for their considerable enhancement, in
particular, in relativistic nuclear model of Walecka are advanced.


title: High p_T hadron spectra in high-energy heavy-ion collisions

abstract:
  We calculate the hadron spectra in high-energy pp, pA and AA collisions
within a pQCD parton model. Analyses of experimental data show that the
modification of the spectra in pA and AA as compared to that in $pp$ collisions
is consistent with multiple parton scattering scenario and is dictated by the
transition from absorptive soft interaction at low p_T to incoherent hard
parton scattering at high p_T. This analysis not only sheds new light on the
limits to the physics analysis based on thermal fire-ball models but also
provides a more quantitative baseline results on which one can study the
effects of parton energy loss in the hadron spectra at high p_T.


title: Why Color-Flavor Locking is Just like Chiral Symmetry Breaking

abstract:
  We review how a classification into representations of color and flavor can
be used to understand the possible patterns of symmetry breaking for color
superconductivity in dense quark matter. In particular, we show how for three
flavors, color-flavor locking is precisely analogous to the usual pattern of
chiral symmetry breaking in the QCD vacuum.


title:
Medium Modified Cross Sections, Temperature and Finite Momentum Effects
  for Antikaon Production in Heavy-Ion Collisions

abstract:
  The medium modifications of antikaons in dense matter are studied in a
coupled channel calculation for scenarios more closely related to the
environment encountered in heavy-ion collisions. We find that the optical
potential of the antikaons turns repulsive or is drastically reduced for finite
momenta or finite temperature. Hence, the antikaon mass does not decrease
substantially in heavy-ion collisions to provide an explanation for the
observed antikaon production rates at threshold. We demonstrate that the
in-medium production cross section of antikaons via pions and Sigma hyperons is
remarkably enhanced up to an order of magnitude. The effect of in medium
correction on the resulting kaon spectra is studied within a transport model.
We find that both in medium correction lead to about the same enhancement of
the spectrum. However, once the temperature dependence is taken into account no
enhancement is found.


title: Reconstructing the Freeze-out State in Pb+Pb Collisions at 158 AGeV/c

abstract:
  For a class of analytical parametrizations of the freeze-out state of
relativistic heavy ion collisions, we perform a simultaneous analysis of the
single-particle m_t-spectra and two-particle Bose-Einstein correlations
measured in central Pb+Pb collisions at the CERN SPS. The analysis includes a
full model parameter scan with chi^2 confidence levels. A comparison of
different transverse density profiles for the particle emission region allows
for a quantitative discussion of possible model dependencies of the results.
Our fit results suggest a low thermal freeze-out temperature T approximately 95
+- 15 MeV and a large average transverse flow velocity of about 0.55c +- 0.07c.
Moreover, the fit favours a box-shaped transverse density profile over a
Gaussian one. We discuss the origins and the consequences of these results in
detail. In order to reproduce the measured pion multiplicity our model requires
a positive pion chemical potential. A study of the pion phase-space density
indicates \mu_\pi approximately 60 MeV for T = 100 MeV.


title:
Beyond the Shell Model: The Canonical Nuclear Many-Body Problem as an
  Effective Theory

abstract:
  We describe a strategy for attacking the canonical nuclear structure problem
---bound-state properties of a system of point nucleons interacting via a
two-body potential---which involves an expansion in the number of particles
scattering at high momenta, but is otherwise exact. The required
self-consistent solutions of the Bloch-Horowitz equation for effective
interactions and operators are obtained by an efficient Green's function method
based on the Lanczos algorithm. We carry out this program for the simplest
nuclei, d and $^3$He, to contrast a rigorous effective theory with the shell
model, thereby illustrating several of the uncontrolled approximations in the
latter.


title: Flow and equation of state in heavy-ion collisions

abstract:
  The status of flow in heavy-ion collisions and of inference of
hadronic-matter properties is reviewed.


title: Phi-measure of azimuthal fluctuations

abstract:
  The event-by-event azimuthal fluctuations in high-energy heavy-ion collisions
are analyzed by means of the so-called Phi-measure. The fluctuations due to the
collective transverse flow and those caused by the quantum statistics and
resonance decays in the hadron gas are discussed in detail.


title:
Calculations for populations of selected isotopes in intermediate energy
  heavy ion collisions

abstract:
  We compute the populations of isotopes of Boron, Carbon and Nitrogen measured
experimentally in intermediate energy heavy ion collisions. A two component
soluble statistical model is used to find the initial populations of different
nuclei at a finite temperature. These initial populations are both in particle
stable and particle unstable states. The particle unstable states then decay.
The final populations after these decays are computed and compared with
experimental data.


title: Charge symmetry breaking in mirror nuclei from quarks

abstract:
  The binding energy differences of the valence proton and neutron of the
mirror nuclei, $^{15}$O -- $^{15}$N, $^{17}$F -- $^{17}$O, $^{39}$Ca --
$^{39}$K and $^{41}$Sc -- $^{41}$Ca, are calculated using the quark-meson
coupling (QMC) model. The calculation involves nuclear structure and shell
effects explicitly. It is shown that binding energy differences of a few
hundred keV arise from the strong interaction, even after subtracting all
electromagnetic corrections. The origin of these differences may be ascribed to
the charge symmetry breaking effects set in the strong interaction through the
u and d current quark mass difference.


title:
Chiral symmetry in electromagnetically induced resonant two hadron
  production

abstract:
  We report on recent progress on the chiral unitary approach, analogous to the
effective range expansion in Quantum Mechanics, which is shown to have a much
larger convergence radius than ordinary chiral perturbation theory, allowing
one to reproduce data for meson meson interaction up to 1.2 GeV. Applications
to physical processes so far unsuited for a standard chiral perturbative
approach are presented, in which two hadrons, either two mesons or a meson and
a baryon, in a resonant state are produced in photoproduction processes.


title:
Superdeformed bands in 32S and neighboring nuclei predicted within the
  Hartree-Fock method

abstract:
  Superdeformed configurations in 32S, and in neighboring nuclei 33S, 31S,
33Cl, and 31P, are determined within the Hartree-Fock approach with the Skyrme
interaction. Energies, angular momenta, quadrupole moments, particle-emission
Q-values, and relative alignments and quadrupole moments are calculated for a
number of superdeformed rotational bands in these nuclei. A new mechanism
implying an existence of signature-separated rotational bands, distinct from
the well-known signature-split bands, is discussed and associated with the
time-odd channels of effective interactions.


title:
Rotating nuclei at extreme conditions: Cranked Relativistic Mean Field
  Description

abstract:
  The cranked relativistic mean field (CRMF) theory is applied for the
description of superdeformed (SD) rotational bands observed in $^{153}$Ho. The
question of the structure of the so-called SD band in $^{154}$Er is also
addressed and a brief overview of applications of CRMF theory to the
description of rotating nuclei at extreme conditions is presented.


title:
Cranked Relativistic Hartree-Bogoliubov Theory: Superdeformed Bands in
  the $A\sim 190$ Region

abstract:
  Cranked Relativistic Hartree-Bogoliubov (CRHB) theory is presented as an
extension of Relativistic Mean Field theory with pairing correlations to the
rotating frame. Pairing correlations are taken into account by a finite range
two-body force of Gogny type and approximate particle number projection is
performed by Lipkin-Nogami method. This theory is applied to the description of
yrast superdeformed rotational bands observed in even-even nuclei of the $A\sim
190$ mass region. Using the well established parameter sets NL1 for the
Lagrangian and D1S for the pairing force one obtains a very successful
description of data such as kinematic ($J^{(1)}$) and dynamic ($J^{(2)}$)
moments of inertia without any adjustment of new parameters. Within the present
experimental accuracy the calculated transition quadrupole moments $Q_t$ agree
reasonably well with the observed data.


title:
Weak Interaction Rates Of sd-Shell Nuclei In Stellar Environment
  Calculated in the Proton-Neutron Quasiparticle Random Phase Approximation

abstract:
  Allowed weak interaction rates for sd-shell nuclei in stellar environment are
calculated using a generalized form of proton-neutron quasiparticle RPA model
with separable Gamow-Teller forces. Twelve different weak rates are calculated
for each nucleus as a function of temperature and density. This project
consists of calculation of weak rates for a total of 709 nuclei with masses
ranging from A = 18 to 100. This paper contains calculated weak rates for
sd-shell nuclei. The calculated capture and decay rates take into consideration
the latest experimental energy levels and ft value compilations. The results
are also compared with earlier works. Particle emission processes from excited
states, previously ignored, are taken into account, and are found to
significantly affect some beta decay rates.


title:
Effective Widths and Effective Number of Phonons of Multiphonon Giant
  Resonances

abstract:
  We discuss the origin of the difference between the harmonic value of the
width of the multiphonon giant resonances and the smaller observed value.
Analytical expressions are derived for both the effective width and the average
cross-section. The contribution of the Brink-Axel mechanism in resolving the
discrepancy is pointed out.


title: Particle-hole level densities in deformed nuclei

abstract:
  Microscopic Combinatorial approach is used to calculate the state and level
densities with fixed exciton numbers, in some actinide nuclei. Deformed
Saxon-Woods shell model was used as a basis from which all posible
configurations were generated. The pairing interaction was taken into account
by applying the BCS theory to each configurations. Both the spin and parity
distributions were obtained,considering the deformation of the nucleus.
Relevance of the result to parity nonconservation studies involving epithermal
neutrons on $^{238}$U and $^{232}$Th is discussed.


title: Charged current weak production of the Delta resonance

abstract:
  The charge changing weak production of Delta in nucleons and nuclei is
studied. The reactions e^{-} p -> Delta^{0} \nu_{e} and e^{+} p -> Delta^{++}
\bar{\nu}_{e} are considered as a possible source of information about the weak
N-Delta transition form factors. The low q^2 BNL data on neutrino production of
Delta are used to extract the axial vector N-Delta coupling, taking into
account the deuteron structure and the Delta width. Finally, pion production
induced by neutrinos in ^{16}O in the Delta region, relevant to atmospheric
neutrino experiments, is investigated.


title:
An inversion procedure for coupled-channel scattering: determining the
  deuteron-nucleus tensor interaction

abstract:
  We present a practical $S$-matrix to potential inversion procedure for
coupled-channel scattering. The inversion technique developed is applied to
non-diagonal $S^J_{ll'}$ for spin one projectiles, yielding a tensor
interaction $T_{\rm R}$, and is also applicable to spin-1/2 plus spin-1/2
scattering. The method is a generalization of the iterative-perturbative, IP,
method. It is tested and evaluated and we investigate the degree of uniqueness
of the potential, particularly for cases where there is insufficient
information to define the potential uniquely. We examine the potentials which
result when the $S$-matrix is generated from a $T_{\rm P}$ interaction. We also
develop the generalisation, using established procedures, of IP
$S$-matrix-to-potential inversion to direct observable-to-potential inversion.
This `direct inversion' procedure is demonstrated to be an efficient method for
finding a multi-component potential including a $T_{\rm R}$ interaction fitting
multi-energy $\sigma$, ${\rm i}T_{11}$, $T_{20}$, $T_{21}$ and $T_{22}$ data
for the scattering of spin-1 nuclei from spin-zero target. It is applicable to
other channel spin 1 cases.


title:
Testing and improvements of gamma-ray strength functions for nuclear
  model calculations of nuclear data

abstract:
  A closed-form thermodynamic pole approach,TPA, is developed for average
description of the E1 radiative strength functions using the microcanonical
ensemble for initial states. A semiclassical description of the collective
excitation damping in this method is based on modern physical notion on the
relaxation processes in Fermi systems.The TPA model gives rather accurate means
of simultaneous description of the gamma- decay and photoabsorption strength
functions in the medium and heavy nuclei. It is able to cover a relatively wide
energy interval, ranging from zeroth gamma-ray energy to values above GDR peak
energy, as compared with the others closed-form models for calculation of the
E1 strength.


title:
Stellar Weak Interaction Rates and Energy Losses for fp-Shell Nuclei in
  the Proton-Neutron Quasiparticle Random-Phase Approximation

abstract:
  Nuclear weak interaction rates for fp-shell nuclei in stellar matter and the
associated energy losses are calculated using a modified form of proton-neutron
quasiparticle RPA model with separable Gamow-Teller forces. The stellar weak
rates are calculated over a wide range of densities (10 < \rho Y_{e} (gcm^{-3})
< 10^{11}) and temperatures (10^{7} < T(K) < 30 x 10^{9}). This is the first
ever extensive compilation of weak interaction rates in stellar matter
calculated over a wide temperature-density grid and over a larger mass range.
The calculated capture and decay rates take into consideration the latest
experimental energy levels and ft value compilations. We have calculated
stellar weak interaction rates for a total of 619 nuclei in the mass range A =
40 to 100. These also include many important neutron-rich nuclei which play an
important role in the evolution process of stellar collapse. This is our second
paper in a series where we will be presenting our results on an abbreviated
scale of temperature and density for the mass range A = 18 to 100. This paper
contains the stellar weak rates in the mass range 40 to 60.


title:
Quasiparticle Random Phase Approximation with inclusion of the Pauli
  Exclusion Principle

abstract:
  Limitations of the Quasiparticle Random Phase Approximation (QRPA) are
studied within an exactly solvable model, with a two body interaction of Fermi
type. A special attention is paid to the violation of the Pauli exclusion
principle (PEP) in solving the QRPA equation. A comparison of the exact
solution, obtained by the diagonalization of a schematic nuclear Hamiltonian
and those obtained within the standard QRPA, the renormalized QRPA, the QRPA
with pertubative treatment of the PEP and the QRPA with exact consideration of
the PEP, is presented. The agreement quality is judged in terms of the
quasiparticle number operator matrix elements in the ground state and in the
first excited states, of the beta transition amplitudes, of the Ikeda sum rule
and of the nuclear matrix element for the double beta decay. We have found that
restoring the PEP, the QRPA solutions are considerably stabilized and a better
agreement with the exact solution is obtained.


title: $pp\to pp\omega$ reaction near threshold

abstract:
  We analyze the total cross section data for $pp \to pp\omega$ near threshold
measured recently at SATURNE. Using an effective range approximation for the
on-shell $pp$ S-wave final state interaction we extract from these data the
modulus $|\Omega| = 0.53$ fm$^4$ of the threshold transition amplitude
$\Omega$. We present a calculation of various (tree-level) meson exchange
diagrams contributing to $\Omega$. It is essential that $\omega$-emission from
the anomalous $\omega\rho\pi$-vertex interferes destructively with
$\omega$-emission from the proton lines. The contribution of scalar
$\sigma$-meson exchange to $\Omega$ turns out to be negligibly small. Without
introducing off-shell meson-nucleon form factors the experimental value
$|\Omega|=0.53$ fm$^4$ can be reproduced with an $\omega N$-coupling constant
of $g_{\omega N}=10.7$. The results of the present approach agree qualitatively
with the J\"ulich model. We also perform a combined analysis of the reactions
$pp\to pp\pi^0, pn\pi^+, pp\eta, pp\omega$ and $pn\to pn\eta$ near threshold.


title:
Stellar Weak Interaction Rates and Energy Losses for fp-Shell Nuclei
  Calculated in the Proton-Neutron Quasiparticle Random-Phase Approximation
  (II).(A = 61 to 80)

abstract:
  Weak interaction rates and the associated energy losses for massive nuclei in
the fp-shell are calculated in stellar matter using a modified form of
proton-neutron quasiparticle RPA model with separable Gamow-Teller forces. A
total of 209 nuclei with mass numbers ranging from A = 61 to 80 are considered
here for the calculation of weak rates. These also include many neutron-rich
nuclei which play a key role in the dynamics of the core collapse calculations.
The stellar weak rates are calculated over a wide range of densities (10 < \rho
Y_{e} (gcm^{-3}) < 10^{11}) and temperatures (10^{7} < T(K) 30 x 10^{9}). This
is our third paper in a series starting with the calculation of stellar weak
rates for nuclei in the sd-shell. The calculated rates take into consideration
the latest experimental energy levels and ft value compilations. The effect of
particle emission processes is taken into account and the energies and
probabilities of these particle emission processes are also calculated in
stellar environment. Our results are presented here on an abbreviated scale of
temperature and density.


title: Strange matter in the string-flip model

abstract:
  We employ variational Monte Carlo methods to study the transition to strange
matter in a simple one-dimensional string-flip model with two flavors and two
colors of quarks. The dynamics of the system are described in terms of a
many-body potential that confines quarks within hadrons, yet enables the
hadrons to separate without generating unphysical long-range van der Waals
forces. The model has ``natural'' low- and high-density limits: it behaves as a
system of isolated hadrons at low density and as a Fermi gas of quarks at high
density. We show that the system exhibits a transition to strange matter
characterized by an increase in the length-scale for confinement. Yet the small
increase at the transition region --- of only ten percent --- suggests that
clustering correlations remain strong well into the strange-matter domain. Our
results put into question descriptions of strange matter in terms of
noninteracting, or weakly interacting, quarks.


title:
Applications of computed Nuclear Structure Functions to Inclusive
  Scattering R-ratios and their Moments

abstract:
  We discuss applications of previously computed nuclear structure functions
(SF) to inclusive cross sections, compare predictions with recent CEBAF data
and perform two scaling tests. We mention that the large $Q^2$ plateau of
scaling functions may only in part be due to the asymptotic limit of SF, which
prevents the extraction of the nucleon momentum distribution in a
model-independent way. We show that there may be sizable discrepancies between
computed and semi-heuristic estimates of SF ratios. We compute ratios of
moments of nuclear SF and show these to be in reasonable agreement with data.
We speculate that an effective theory may underly the model for the nuclear SF,
which produces overall agreement with several observables.


title:
Transport calculation of dilepton production at ultrarelativistic
  energies

abstract:
  Dilepton spectra are calculated within the microscopic transport model UrQMD
and compared to data from the CERES experiment. The invariant mass spectra in
the region 300 MeV < M < 600 MeV depend strongly on the mass dependence of the
$\rho$ meson decay width which is not sufficiently determined by the Vector
Meson Dominance model. A consistent explanation of both the recent Pb+Au data
and the proton induced data can be given without additional medium effects.


title: Quasifree Kaon Photoproduction on Nuclei

abstract:
  Investigations of the quasifree reaction A$(\gamma, K Y)$B are presented in
the distorted wave impulse approximation (DWIA). For this purpose, we present a
revised tree-level model of elementary kaon photoproduction that incorporates
hadronic form factors consistent with gauge invariance, uses SU(3) values for
the Born couplings and uses resonances consistent with multi-channel analyses.
The potential of exclusive quasifree kaon photoproduction on nuclei to reveal
details of the hyperon-nucleus interaction is examined. Detailed predictions
for the coincidence cross section, the photon asymmetry, and the hyperon
polarization and their sensitivities to the ingredients of the model are
obtained for all six production channels. Under selected kinematics these
observables are found to be sensitive to the hyperon-nucleus final state
interaction. Some polarization observables are found to be insensitive to
distortion effects, making them ideal tools to search for possible medium
modifications of the elementary amplitude.


title: Nucleon form factors and a nonpointlike diquark

abstract:
  Nucleon form factors are calculated on q^2 in [0,3] GeV^2 using an Ansatz for
the nucleon's Fadde'ev amplitude motivated by quark-diquark solutions of the
relativistic Fadde'ev equation. Only the scalar diquark is retained, and it and
the quark are confined. A good description of the data requires a nonpointlike
diquark correlation with an electromagnetic radius of 0.8 r_pi. The composite,
nonpointlike nature of the diquark is crucial. It provides for diquark-breakup
terms that are of greater importance than the diquark photon absorption
contribution.


title: Is there np pairing in odd-odd N=Z nuclei?

abstract:
  The binding energies of even-even and odd-odd N=Z nuclei are compared. After
correcting for the symmetry energy we find that the lowest T=1 state in odd-odd
N=Z nuclei is as bound as the ground state in the neighboring even-even
nucleus, thus providing evidence for isovector np pairing. However, T=0 states
in odd-odd N=Z nuclei are several MeV less bound than the even-even ground
states. We associate this difference with a pair gap and conclude that there is
no evidence for an isoscalar pairing condensate in N=Z nuclei.


title: Information Theory, Quark Clusters in Nuclei, and Parton Distributions

abstract:
  The procedure of maximization of information entropy can be used to improve
our knowledge of parton distributions. This method has been applied in order to
achieve improved description of the nuclear effect in Y production due to gluon
distribution modification in nuclei.


title: Correlations derived from Modern Nucleon-Nucleon Potentials

abstract:
  Various modern nucleon-nucleon (NN) potentials yield a very accurate fit to
the nucleon-nucleon scattering phase shifts. The differences between these
interactions in describing properties of nuclear matter are investigated.
Various contributions to the total energy are evaluated employing the Hellmann
- Feynman theorem. Special attention is paid to the two-nucleon correlation
functions derived from these interactions. Differences in the predictions of
the various interactions can be traced back to the inclusion of non-local
terms.


title: Microscopic Studies on Two-Phonon Giant Resonances

abstract:
  A new class of giant resonances in nuclei, namely double giant resonances, is
discussed. They are giant resonances built on top of other giant resonances.
Investigation on their properties, together with similar studies on low-lying
two-phonon states, should give an answer on how far the harmonic picture of
boson-type excitations holds in the finite fermion systems like atomic nuclei.
  The main attention in this review is paid to double giant dipole resonances
(DGDR) which are observed in relativistic heavy ion collisions with very large
cross sections. A great experimental and theoretical effort is underway to
understand the reaction mechanism which leads to the excitation of these states
in nuclei, as well as the better microscopic understanding of their properties.
The Coulomb mechanism of the excitation of single and double giant resonances
in heavy ion collision at different projectile energies is discussed in
details. A contribution of the nuclear excitation to the total cross section of
the reaction is also considered. The Coulomb excitation of double resonances is
described within both, the second-order perturbation theory approach and in
coupled-channels calculation. The properties of single and double resonances
are considered within the phenomenologic harmonic vibrator model and
microscopic quasiparticle-RPA approach. For the last we use the
Quasiparticle-Phonon Model (QPM) the basic ideas and formalism of which are
presented. The QPM predictions of the DGDR properties (energy centroids,
widths, strength distributions, anharmonicities and excitation cross sections)
are compared to predictions of harmonic vibrator model, results of other
microscopic calculations and experimental data available.