title: $\beta^+$ and electron capture of fp shell nuclei with $Tz=-2$

abstract:
  Allowed $\beta^+$ branches of very proton-rich $fp$ shell $Tz=-2$ nuclei at
the proton drip-line are calculated in the full fp valence space. The $\beta^+$
decay half-lives calculated with the standard quenching factor
($g^{eff}_{A}/g_{A}$)=0.74 are in good agreement with existing experimental
data. Detailed branching Gamow-Teller strength are predicted but comparison
with experiment is still difficult since, in most cases, spectroscopic
information is not yet available.


title: Optimized Discretization of Sources Imaged in Heavy-Ion Reactions

abstract:
  We develop the new method of optimized discretization for imaging the
relative source from two particle correlation functions. In this method, the
source resolution depends on the relative particle separation and is adjusted
to available data and their errors. We test the method by restoring assumed pp
sources and then apply the method to pp and IMF data. In reactions below 100
MeV/nucleon, significant portions of the sources extend to large distances (r >
20 fm). The results from the imaging show the inadequacy of common Gaussian
source-parametrizations. We establish a simple relation between the height of
the pp correlation function and the source value at short distances, and
between the height and the proton freeze-out phase-space density.


title:
The structure of the QED-Vacuum and Electron-Positron Pair Production in
  Super-Intense, pulsed Laser Fields

abstract:
  We discuss electron-positron pair-production by super-intense, short laser
pulses off the physical vacuum state locally deformed by (stripped) nuclei with
large nuclear charges. Consequences of non-perturbative vacuum polarisation
resulting from such a deformation are shortly broached. Production
probabilities per pulse are calculated.


title: Proton drip-line nuclei in Relativistic Hartree-Bogoliubov theory

abstract:
  Ground-state properties of spherical even-even nuclei $14\leq Z \leq 28$ and
$N=18,20,22$ are described in the framework of Relativistic Hartree Bogoliubov
(RHB) theory. The model uses the NL3 effective interaction in the mean-field
Lagrangian, and describes pairing correlations by the pairing part of the
finite range Gogny interaction D1S. Binding energies, two-proton separation
energies, and proton $rms$ radii that result from fully self-consistent RHB
solutions are compared with experimental data. The model predicts the location
of the proton drip-line. The isospin dependence of the effective spin-orbit
potential is discussed, as well as pairing properties that result from the
finite range interaction in the $pp$ channel.


title:
Intermediate mass excess of dilepton production in heavy ion collisions
  at BEVALAC energies

abstract:
  Dielectron mass spectra are examined for various nuclear reactions recently
measured by the DLS collaboration. A detailed description is given of all
dilepton channels included in the transport model UrQMD 1.0, i.e. Dalitz decays
of $\pi^0,\eta,\omega,\eta'$ mesons and of the $\Delta(1232)$ resonance, direct
decays of vector mesons and $pn$ bremsstrahlung. The microscopic calculations
reproduce data for light systems fairly well, but tend to underestimate the
data in $pp$ at high energies and in $pd$ at low energies. These conventional
sources, however, cannot explain the recently reported enhancement for
nucleus-nucleus collisions in the mass region 0.15 GeV<$M_{ee}$<0.6 GeV. Chiral
scaling and $\omega$ meson broadening in the medium are investigated as a
source of this mass excess. They also cannot explain the recent DLS data.


title:
Asymmetry in omega meson photoproduction and the phase of omega-pi-gamma
  coupling

abstract:
  We analyze the double polarization asymmetry of the omega-meson
photoproduction in the vector-meson-dominance model of diffractive production
and the one-pion exchange model. We find that the longitudinal beam-target
asymmetry is very sensitive to the real part of the diffractive photoproduction
amplitude and to the sign of the omega-pi-gamma coupling because of the
different spin structures of the amplitudes associated with the different
mechanisms.


title: Stability and Representation Dependence of the Quantum Skyrmion

abstract:
  A constructive realization of Skyrme's conjecture that an effective pion mass
``may arise as a self consistent quantal effect'' based on an ab initio quantum
treatment of the Skyrme model is presented. In this quantum mechanical Skyrme
model the spectrum of states with $I=J$, which appears in the collective
quantization, terminates without any infinite tower of unphysical states. The
termination point depends on the model parameters and the dimension of the
SU(2) representation. Representations, in which the nucleon and $\Delta_{33}$
resonance are the only stable states, exist. The model is developed for both
irreducible and reducible representations of general dimension. States with
spin larger than 1/2 are shown to be deformed. The representation dependence of
the baryon observables is illustrated numerically.


title:
Lorentz Multiplet Structure of Baryon Spectra and Relativistic
  Description

abstract:
  The pole positions of the various baryon resonances are known to reveal
well-pronounced clustering, so-called Hoehler clusters. For nonstrange baryons
the Hoehler clusters are shown to be identical to Lorentz multiplets of the
type (j,j)*[(1/2,0)+(0,1/2)] with j being a half-integer. For the Lambda
hyperons below 1800 MeV these clusters are shown to be of the type [(1,0)+
(0,1)]*[(1/2,0)+(0,1/2)] while above 1800 MeV they are parity duplicated
(J,0)+(0,J) (Weinberg-Ahluwalia) states. Therefore, for Lambda hyperons the
restoration of chiral symmetry takes place above 1800 MeV. Finally, it is
demonstrated that the description of spin-3/2 particles in terms of a 2nd rank
antisymmetric Lorentz tensor with Dirac spinor components does not contain any
off-shell parameters and avoids the main difficulties of the Rarita-Schwinger
description based upon a 4-vector with Dirac spinor components.


title:
On the Delta-Nucleon and Rho - Pi Splittings: A QCD-inspired Look in
  Free Hadrons versus Nuclei

abstract:
  Relationships between mass intervals for free hadrons and in nuclei are
studied in two theoretical approaches inspired by QCD: naive quark model and
skyrmion model, taking one example each from mesons and baryons, that of pi-rho
splitting in mesons, and nucleon-Delta splitting in baryons. Possible
deconfinement effects in nuclei are examined.


title:
A quantum kinetic equation for Fermi-systems including three-body
  correlations

abstract:
  A single-time quantum transport equation, which includes effects beyond the
quasiparticle approximation, is derived for Fermi-systems in the framework of
non-equilibrium real-time Green's functions theory. Ternary correlations are
incorporated in the kinetic description via a cluster expansion for the
self-energies (e.g., the transport vertex and the width) truncated at the level
of three-body scattering amplitudes. A finite temperature/density formulation
of the three-body problem is given. Corresponding three-body equations reduce
to the well-known Faddeev equations in the vacuum limit. In equilibrium the
equation of state contains virial corrections proportional to the third quantum
virial coefficient.


title: Kaon Electromagnetic Production on Nuclei

abstract:
  The formation and excitation of hypernuclei through kaon photoproduction is
reviewed. Basic features of the production process are emphasized. The
possibility of extracting new information on hypernuclear structure and on the
wave function of the bound $\Lambda$ is discussed. New results are presented
for the quasifree production process $A(\gamma, K \Lambda)B$. Observables of
this reaction are shown to be sensitive to the $\Lambda$-nucleus final state
interaction.


title:
Intermediate mass dilepton production in heavy-ion collisions at SPS
  energies

abstract:
  Through the analysis of HELIOS-3 data on dilepton spectra, we demonstrate the
importance of secondary processes for the dilepton production in heavy-ion
collisions in the intermediate mass region. We find that, while the dilepton
spectra in proton-induced reactions can be nicely explained by the decay of
primary vector mesons, charmed hadrons, and initial Drell-Yan processes, the
strong enhancement seen in the heavy-ion data comes mainly from the secondary
meson-meson interactions which are unique to heavy-ion collisions.


title: Fragments in Gaussian Wave-Packet Dynamics with and without Correlations

abstract:
  Generalization of Gaussian trial wave functions in quantum molecular dynamics
models is introduced, which allows for long-range correlations characteristic
for composite nuclear fragments. We demonstrate a significant improvement in
the description of light fragments with the correlations. Utilizing either type
of Gaussian wave functions, with or without correlations, however, we find that
we cannot describe fragment formation in a dynamic situation. Composite
fragments are only produced in simulations if these fragments are present as
clusters in the substructure of original nuclei. The difficulty is traced to
the delocalization of wave functions during emission. Composite fragments are
produced abundantly in the Gaussian molecular dynamics in the limit hbar -> 0.


title:
Level density and level density parameter in medium heavy nuclei
  including thermal and quantal fluctuation effects

abstract:
  In a realistic application of the SPA + RPA theory for calculation of the
nuclear level densities we find that quantal fluctuation corrections (RPA) are
important even up to temperature $T = 2.0 MeV$. This leads to a good agreement
between calculated numbers and the available experimental data for $^{104}Pd$
and $^{114}Sn$, particularly the excitation energy ($E^*$) dependence.
Furthermore, we also argue that $a=S^2/4E^*$ is the only correct definition of
the level density parameter in the present context which is also consistent
with the Bethe like level density formula.


title:
Comment on ``Pionic decay of a possible d' dibaryon and the short-range
  NN interaction''

abstract:
  We comment on calculations of the width of the d' resonance within framework
of quark shell models.


title: Neutrino-induced neutron spallation and the site of the r-process

abstract:
  All of the actinides and roughly half the natural abundance of elements with
mass number A > 70 come from the rapid neutron capture process, or the
r-process. If the r-process, as suggested by many, occurs deep in a supernova,
then it is under the influence of an intense neutrino flux. Here we discuss the
effects of both charged-current and neutral-current neutrino interactions on
the r-process. We show that the multiple-neutron emission induced by both kinds
of neutrino interactions can affect the observed r-process abundance pattern
significantly. In particular, we find that five nuclei below the r-process
abundance peak at A = 195 may be entirely attributed to the neutrino-induced
neutron spallation processes following the r-process freeze-out. Furthermore,
the deduced neutrino fluence agrees with the conditions in the recent supernova
r-process model. These results strongly argue that the r-process occurs in
supernovae. They also provide a sensitive probe for the conditions at the
supernova r-process site.


title: Ground state of N=Z doubly closed shell nuclei in CBF theory

abstract:
  The ground state properties of N=Z doubly closed shell nuclei are studied
within correlated basis function theory. A truncated version of the Urbana v14
realistic potential, with spin, isospin and tensor components, is adopted,
together with state dependent correlations. Fermi hypernetted chain integral
equation and single operator chain approximation are used to evaluate density,
distribution function and ground state energy of 16O and 40Ca. The results
favourably compare with the available, variational MonteCarlo estimates and
provide a first substantial check of the accuracy of the cluster summation
method for state dependent correlations. We achieve in finite nuclei at least
the same level of accuracy in the treatment of non central interactions and
correlations as in nuclear matter. This opens the way for a microscopic study
of medium heavy nuclei ground state using present days realistic hamiltonians.


title: Relativistic Charge Form Factor of the Deuteron

abstract:
  Relativistic integral representation in terms of experimental neutron-proton
scattering phase shifts alone is used to compute the charge form factor of the
deuteron $G_{Cd}(Q^2)$. The results of numerical calculations of
$|G_{Cd}(Q^2)|$ are presented in the interval of the four-momentum transfers
squared $0 \leq Q^2 \leq 35 fm^{-2}$. Zero and the prominent secondary maximum
in $ |G_{Cd}(Q^2)|$ are the direct consequences of the change of sign in the
experimental $^3S_1$- phase shifts. Till the point $Q^2 \simeq 20 fm^{-2}$ the
total relativistic correction to $|G_{Cd}(Q^2)|$ is positive and reaches the
maximal value of 25% at $Q^2 \simeq 14 fm^{-2}$.


title: Competition between standard and exotic double beta decays

abstract:
  We discuss the contributions of higher order terms in weak Hamiltonian to the
standard two-neutrino double beta decay. The formalism for the unique first
forbidden transitions has been developed, and it is shown that they can alter
the two-electron energy spectrum. Yet, their effect is too small to screen the
detection of exotic neutrinoless double beta decays, which are candidates for
testing the physics beyond the standard model.


title: Instanton tunneling and multiphonon giant resonances

abstract:
  The sine-Gordon model is applied to describe the multiphonon giant
resonances.


title:
Theoretical and Experimental K^+ + Nucleus Total and Reaction Cross
  Sections from the KDP-RIA Model

abstract:
  The 5-dimensional spin-0 form of the Kemmer-Duffin-Petiau (KDP) equation is
used to calculate scattering observables [elastic differential cross sections
($d\sigma/d\Omega$), total cross sections ($\sigma_{Tot}$), and reaction cross
sections ($\sigma_{Reac}$})] and to deduce $\sigma_{Tot}$ and $\sigma_{Reac}$
from transmission data for $K^+ + $ $^{6}$Li, $^{12}$C, $^{28}$Si, and
$^{40}$Ca at several momenta in the range $488 - 714 MeV/c$. Realistic
uncertainties are generated for the theoretical predictions. These errors,
mainly due to uncertainties associated with the elementary $K^+ +$ nucleon
amplitudes, are large, so that the disagreement that has been noted between
experimental and theoretical $\sigma_{Tot}$ and $\sigma_{Reac}$ is not
surprising. The results suggest that the $K^+ +$ nucleon amplitudes need to be
much better determined before unconventional medium effects are invoked to
explain the data.


title:
Neutron pick-up pion transfer reactions for the formation of deeply
  bound pionic atoms in $^{208}$Pb

abstract:
  We study $(n,d)$ and (d,$^3$He) reactions on $^{208}Pb$ leading to deeply
bound pionic atoms with one neutron hole being left. We develop a theoretical
model to calculate cross sections of deeply bound pionic atoms and
quasi-elastic pion production. The results are compared with data which have
been obtained so far. We show that the theoretical model describes the data of
both reactions well.


title: Dependence of direct neutron capture on nuclear-structure models

abstract:
  The prediction of cross sections for nuclei far off stability is crucial in
the field of nuclear astrophysics. We calculate direct neutron capture on the
even-even isotopes $^{124-145}$Sn and $^{208-238}$Pb with energy levels,
masses, and nuclear density distributions taken from different
nuclear-structure models. The utilized structure models are a
Hartree-Fock-Bogoliubov model, a relativistic mean field theory, and a
macroscopic-microscopic model based on the finite-range droplet model and a
folded-Yukawa single-particle potential. Due to the differences in the
resulting neutron separation and level energies, the investigated models yield
capture cross sections sometimes differing by orders of magnitude. This may
also lead to differences in the predicted astrophysical r-process paths.
Astrophysical implications are discussed.


title:
On the role of the $\Delta (1232)$ on the transverse nuclear response in
  the $(e,e')$ reaction

abstract:
  The transverse nuclear response to an electromagnetic probe which is limited
to create (or destroyed) a particle-hole ($ph$) or delta-hole ($\Delta h$) pair
is analyzed. Correlations of the random phase approximation (RPA) type and self
energy insertions are considered. For RPA correlations we have developed a
scheme which includes explicitly the $\Delta$ and the exchange terms. Self
energy insertions over $ph$ and $\Delta h$ bubbles are studied. Several
residual interactions based on a contact plus a ($\pi + \rho$)-meson exchange
potential are used. All calculations are performed in non-relativistic nuclear
matter. The main effect of the $\Delta$ is to reduce the intensity over the
nuclear quasi-elastic peak. Exchange RPA terms are very important, while the
self energy depends strongly on the residual interaction employed. We compare
our final result with data for $^{40}Ca$ at momentum transfer $q=410$ and
$q=550$ MeV/c.


title: Parton Cascade Description of Heavy-Ion Collisions at CERN ?

abstract:
  There seems to be a general consensus now that a first glimpse of a QGP-like
effect has become visible in the beautiful NA50 data on J/\psi production and
the `anomalous supression' phenomenon. On the other hand, it is still widely
believed that the dynamics of heavy-ion collisions at CERN SPS energy is
predominantly governed by soft, non-perturbative physics. This is ironic: after
all, it is unlikely that a QGP could be formed if the underlying dynamics were
essentyially soft, rather than that it requires intense quark-gluon production
with sufficient cascade-like reinteractions which drive the matter to large
density and equilibrium. Therefore, I advocate in this contribution that for
ultra-relativistic nucleus-nucleus collisions a description based on the pQCD
interactions and cascade evolution of involved partons can and should be used,
owing to the claim that short-range parton interactions play an important role
at sufficiently high beam energies, including CERN energy sqrt(s) = 20 A GeV.
Here mini-jet production which liberates of quarks and gluons cannot be
considered as an isolated rare phenomenon, but can occur quite copiously and
may lead to complex multiple cascade-type processes.


title: First Extraction of a Spin-Polarizability of the Proton

abstract:
  A proton spin-polarizability characterizing backward Compton scattering has
been extracted from a dispersion analysis of data between 33 and 309 MeV. This
backward spin-polarizability, "delta" = 27.1 +/-2.2(stat+sys) +2.8/-2.4(model)
in units of 10^-4 fm^4, differs significantly from theoretical estimates which
are dominated by pi0 t-channel exchange, and indicates a new contribution from
the non-perturbative spin-structure of the proton. This new value for "delta"
removes an apparent inconsistency in the difference of charge polarizabilities
extracted from data above pi-threshold. Our global result, alpha-beta = 10.11
+/-1.74(stat+sys) +1.22/-0.86 (model) in units of 10^-4 fm^3, is consistent
with the previous world average of data below 155 MeV. Our value for alpha+beta
= 13.23 +/-0.86(stat+sys) +0.20/-0.49(model) is consistent with a recent
re-evaluation of the Baldin sum rule.


title: Multiparticle Bose-Einstein Correlations

abstract:
  Multiparticle symmetrization effects are contributions to the spectra of
Bose-symmetrized states which are not the product of pairwise correlations.
Usually they are neglected in particle interferometric calculations which aim
at determining the geometry of the boson emitting source from the measured
momentum distributions. Based on a method introduced by Zajc and Pratt, we give
a calculation of all multiparticle symmetrization effects to the one- and
two-particle momentum spectra for a Gaussian phase space distribution of
emission points. Our starting point is an ensemble of N-particle
Bose-symmetrized wavefunctions with specified phase space localization. In
scenarios typical for relativistic heavy ion collisions, multiparticle effects
steepen the slope of the one-particle spectrum for realistic particle phase
space densities by up to 20 MeV, and they broaden the relative momentum
dependence of the two-particle correlations. We discuss these modifications and
their consequences in quantitative detail. Also, we explain how multiparticle
effects modify the normalization of the two-particle correlator. The resulting
normalization conserves event probabilities, which is not the case for the
commonly used pair approximation. Finally, we propose a new method of
calculating Bose-Einstein weights from the output of event generators, taking
multiparticle correlations into account.


title: Fermionic Molecular Dynamics and short range correlations

abstract:
  Fermionic Molecular Dynamics (FMD) models a system of fermions by means of
many-body states which are composed of antisymmetrized products of
single-particle states. These consist of one or several Gaussians localized in
coordinate and momentum space. The parameters specifying them are the dynamical
variables of the model. As the repulsive core of the nucleon-nucleon
interaction induces short range correlations which cannot be accommodated by a
Slater determinant, a novel approach, the unitary correlation operator method
(UCOM), is applied. The unitary correlator moves two particles away from each
other whenever their relative distance is within the repulsive core. The
time-dependent variational principle yields the equations of motion for the
variables. Energies of the stationary ground states are calculated and compared
to exact many-body results for nuclei up to Ca 48. Time-dependent solutions are
shown for collisions between nuclei.


title: Parity Violating Elastic Electron Scattering and Coulomb Distortions

abstract:
  Parity violating elastic electron-nucleus scattering provides an accurate and
model independent measurement of neutron densities, because the $Z^0$ couples
primarily to neutrons. Coulomb distortion corrections to the parity violating
asymmetry $A_l$ are calculated exactly using a relativistic optical model.
Distortions significantly reduce $A_l$ in a heavy nucleus. However even with
distortions, an experiment to measure the neutron radius is feasible. This will
aid the interpretation of future atomic parity violation measurements and
provide fundamental nuclear structure information. Coulomb distortions and
small differences between neutron and proton radii could be important for a
standard model test on $^4$He, $^{12}$C or $^{16}$O.


title: Electron capture on iron group nuclei

abstract:
  We present Gamow-Teller strength distributions from shell model Monte Carlo
studies of fp-shell nuclei that may play an important role in the pre-collapse
evolution of supernovae. We then use these strength distributions to calculate
the electron-capture cross sections and rates in the zero-momentum transfer
limit. We also discuss the thermal behavior of the cross sections. We find
large differences in these cross sections and rates when compared to the naive
single-particle estimates. These differences need to be taken into account for
improved modeling of the early stages of type II supernova evolution.


title:
Electromagnetic transition form factors of negative parity nucleon
  resonances

abstract:
  We have calculated the transition form factors for the electromagnetic
excitation of the negative parity resonances of the nucleon using different
models previously proposed and we discuss their results and limits by
comparison with experimental data.


title: Cluster Production in Ultrarelativistic Heavy Ion Collisions

abstract:
  Cluster production in ultrarelativistic heavy ion collision may prove an
interesting tool to extract physical quantities of the fireball.


title: A relativistic study of the nucleon form factors

abstract:
  We perform a calculation of the relativistic corrections to the
electromagnetic elastic form factors of the nucleon obtained with various
Constituent Quark Models. With respect to the non relativistic calculations a
substantial improvement is obtained up to Q^2 about 2 (GeV/c)^2.


title: $J/\psi$ suppression in heavy ion collsions and the QCD phase transition

abstract:
  We suggest that the new regime of $J/\psi$ suppression in Pb-Pb collisions
found by the NA50 experiment at CERN is the result of non-trivial space-time
evolution due to specific behavior of the Equation of State (EOS) near the QCD
phase transition. We also study another suppression channel, the conversion of
$J/\psi$ into $\eta_c$ during the late cool hadronic stage, and find it rather
inefficient.


title:
Reconstructing the Source in Heavy Ion Collisions from Particle
  Interferometry

abstract:
  The preliminary CERN SPS NA49 Pb+Pb 158 GeV/A negative one- and two-particle
spectra at mid-rapidity are consistent with a source of temperature 130 MeV,
lifetime 9 fm/c, transverse flow 0.35, and a transverse geometric size which is
twice as large as the cold Pb nucleus.


title:
The cross section minima in elastic Nd scattering: a ``smoking gun'' for
  three nucleon force effects

abstract:
  Neutron-deuteron elastic scattering cross sections are calculated at
different energies using modern nucleon-nucleon interactions and the
Tucson-Melbourne three-nucleon force adjusted to the triton binding energy.
Predictions based on NN forces only underestimate nucleon-deuteron data in the
minima at higher energies starting around 60 MeV. Adding the three-nucleon
forces fills up those minima and reduces the discrepancies significantly.


title:
Effects of isospin-symmetry violation on tests of the standard model
  using parity-violating electron scattering

abstract:
  The effects of isospin-symmetry breaking on the observables for
parity-violating electron scattering are investigated within the framework of
the nuclear shell model for 12C, 16O, and 28Si. Contributions due to mixing
with low-lying states as well as admixtures of 1p-1h configurations (via the
radial wave functions) are accounted for. It is found that isospin-mixing can
be important, and the consequences regarding precision tests of the standard
model are addressed.


title: Chiral Symmetry Restoration and Parity Mixing

abstract:
  We derive the expressions of the vector and axial current from a chiral
Lagrangian restricted to nucleons and pions. They display mixing terms between
the axial and vector currents. We study the modifications in the nuclear medium
of the coupling constants of the axial current, namely the pion decay constant
and the nucleonic axial one due to the requirements of chiral symmetry. We
express the renormalizations in terms of the local scalar pion density. The
latter also governs the quark condensate evolu- tion and we discuss the link
between this evolution and the renormaliza- tions. In the case of the nucleon
axial coupling constant this renormali- zation corresponds to a new type of
exchange currents, with two exchanged pions. We give an estimate for the
resulting quenching. Although moderate it helps explaining the quenching
experimentally observed.


title: Electrons and Nuclei: Fundamental Interactions and Structure

abstract:
  Examples are given of the usefulness of electrons in interaction with nuclei
for probing fundamental interactions and structure


title: NN Scattering: Chiral Predictions for Asymptotic Observables

abstract:
  We assume that the nuclear potential for distances larger than 2.5 fm is
given just by the exchanges of one and two pions and, for the latter, we adopt
a model based on chiral symmetry and subthreshold pion-nucleon amplitudes,
which contains no free parameters. The predictions produced by this model for
nucleon-nucleon observables are calculated and shown to agree well with both
experiment and those due to phenomenological potentials.


title:
Mass number scaling in ultra-relativistic nuclear collisions from a
  hydrodynamical approach

abstract:
  We study the different nucleus-nucleus collisions, O+Au, S+S, S+Ag, S+Au and
Pb+Pb, at the CERN-SPS energy in a one-fluid hydrodynamical approach using a
parametrization based on baryon stopping in terms of the thickness of colliding
nuclei. Good agreement with measured particle spectra is achieved. We deduce
the mass number scaling behaviour of the initial energy density. We find that
the equilibration time is nearly independent of the size of the colliding
nuclei.


title: Highlight of the QCD Parallel Session

abstract:
  I will give a review with some comments of the parallel session on QCD and
the related talks in the Quark Matter'97 meeting.


title:
Parity-Violating Excitation of the \Delta(1232): Hadron Structure and
  New Physics

abstract:
  We consider prospects for studying the parity-violating (PV) electroweak
excitation of the \Delta(1232) resonance with polarized electron scattering.
Given present knowledge of Standard Model parameters, such PV experiments could
allow a determination of the N -> \Delta electroweak helicity amplitudes. We
discuss the experimental feasibility and theoretical interpretability of such a
determination as well as the prospective implications for hadron structure
theory. We also analyze the extent to which a PV N -> \Delta measurement could
constrain various extensions of the Standard Model.


title: Direct Quark Mechanism for Weak $\Lam N \leftrightarrow NN$ Processes

abstract:
  Two body weak processes $\Lambda N \leftrightarrow NN$ are studied from the
viewpoint of quark substructure of baryons.They can be studied in nonmesonic
weak decays of hypernuclei and also hyperon production in the $NN$ scattering.
The direct quark mechanism in contrast to the one-pion exchange mechanism is
shown to give sizable $\di=3/2$ contribution in the J=0 channel. Nonmesonic
decay rates of $^4_{\Lambda}$H, $^4_{\Lambda}$He, and $^5_{\Lambda}$He agree
with the current experimental data fairly well. Especially the $n/p$ ratio is
enhanced by the direct quark contribution. The cross sections for $pn\to \Lam
p$ scattering are studied in the quark cluster model approach.


title: Spin observables for the pd <-> pi+ t process around the Delta resonance

abstract:
  The proton analyzing power Ay0 and the deuteron tensor analyzing power T20
are evaluated for the pd <-> pi+ t process, in the energy region around and
above the Delta resonance. These calculations extend a previous analysis of the
excitation function and differential cross-section, based on a model embodying
one-- and two-body p-wave absorption mechanisms and isobar excitation. The
three-nucleon bound state and the pd scattering state are evaluated through
Faddeev techniques for both the Bonn and Paris potentials. The spin variables
exhibit a greater sensitivity to the number of included three-nucleon partial
waves than the cross-sections, while the role played by the initial-- or
final-state interactions appears to be small. The results for the tensor
analyzing power at backward angles show a non-negligible dependence on the
potentials employed, consistently with what has been previously found for the
cross-sections. The calculation of spin observables gives a clear indication
that other reaction mechanisms (presumably s-wave two-body absorption) have to
be included in the model, in order to reproduce the experimental data below the
Delta-resonance, in analogy with the simpler pp <-> pi+ d process.


title:
pp <-> pi+ d process at low energy: Interplay between s-- and p-wave
  mechanisms

abstract:
  The large variety of experimental data around the pion-production threshold
are compared with a meson-exchange isobar model which includes the pion-nucleon
interaction in s-- and p-waves. Theoretical results obtained with two different
NN potentials (Bonn and Paris) indicate that the behavior of the excitation
function at threshold is sensitive to the details of the NN correlations. The
complete model presented, while developed originally to reproduce the reaction
around the Delta resonance, is shown to describe well the integral
(Coulomb-corrected) cross-section at threshold along with its angular
distribution. At low energies the angular dependence of the analyzing power Ay0
is well reproduced also. Finally, the energy dependence of the analyzing power
for theta=90 from threshold up to the Delta resonance is considered and
discussed.


title:
Low Freeze-out Temperature and High Collective Velocities in
  Relativistic Heavy-Ion Collisions

abstract:
  On the basis of a nine-parameter expanding source model that includes special
relativity, quantum statistics, resonance decays, and freeze-out on a realistic
hypersurface in spacetime, we analyze in detail invariant pi+, pi-, K+, and K-
one-particle multiplicity distributions and pi+ and K+ two-particle
correlations in nearly central collisions of Si + Au at a laboratory bombarding
energy per nucleon of 14.6 GeV/c. By considering separately the one-particle
data and the correlation data, we find that the central baryon density, nuclear
temperature, transverse collective velocity, longitudinal collective velocity,
and source velocity are determined primarily by one-particle multiplicity
distributions and that the transverse radius, longitudinal proper time, width
in proper time, and pion incoherence fraction are determined primarily by
two-particle correlations. By considering separately the pion data and the kaon
data, we find that although the pion freeze-out occurs somewhat later than the
kaon freeze-out, the 99% confidence-level error bars associated with the two
freeze-outs overlap. These and other detailed studies confirm our earlier
conclusion based on the simultaneous consideration of the pion and kaon
one-particle and correlation data that the freeze-out temperature is less than
100 MeV and that both the longitudinal and transverse collective
velocities--which are anti-correlated with the temperature--are substantial. We
also discuss the flaws in several previous analyses that yielded a much higher
freeze-out temperature of approximately 140 MeV for both this reaction and
other reactions involving heavier projectiles and/or higher bombarding
energies.


title: Strange Isosinglet Versus Octet Scalar Axial Current

abstract:
  The flavor SU(3)_f group symmetry of QCD is systematically considered as the
heavy c quark limit of SU(4)_f. Within that scheme we argue that the U(1)_A
anomaly prevents Gell-Mann's choice for the realization of the su(4)_f (and
thereby the su(3)_f) algebra for the particular case of the neutral axial
currents. Rather, Weyl's choice for the SU(4)_f generators has to be used which
leads to a neutral strong axial current having same structure (up to a constant
factor) as the weak one.


title: Exchange Currents in Photoproduction of Baryon Resonances

abstract:
  We calculate photoexcitation amplitudes for several nucleon and delta
resonances. We use a chiral quark model including two-body exchange currents.
The two-body currents give important contributions. For the delta (1232) and
the D13 (1520) we observe that the individual exchange current contributions
considerably cancel each other while in the case of the Roper resonance and the
S11 (1535) we get a reinforcement of the two-body amplitudes. In comparison
with present experimental data, we obtain both for the S11 (1535) and for the
Roper resonance an improvement with respect to the impulse approximation.


title: Observation of the Mott Effect in Heavy Ion Collisions

abstract:
  Possibility of observing the Mott momentum in the distribution of the
deuterons produced in the process $p + n \to d + \gamma$, in the first stage of
a nuclear reaction is presented. The correlation of a hard photon with a
deuteron allows to select those deuterons produced at the beginning of a
reaction.


title: Comment on "New modes of halo excitations in the 6He nucleus"

abstract:
  We try to explain the differences in the 6He dipole strength function in
refs. [1] and [2]. We perform the full basis calculation of the strength
function with the same renormalized interaction as in [1] and show that the
size of the basis, needed for converged calculations of the 6He continuum
spectrum, is much larger than that for the discrete spectrum. The renormalized
interaction of [1] therefore cannot be used for the continuum spectrum
calculations with the same basis as for the ground state.


title: A New Expansion for Nucleon-Nucleon Interactions

abstract:
  We introduce a new and well defined power counting for the effective field
theory describing nucleon-nucleon interactions. Because of the large NN
scattering lengths it differs from other applications of chiral perturbation
theory and is facilitated by introducing an unusual subtraction scheme and
renormalization group analysis. Calculation to subleading order in the
expansion can be done analytically, and we present the results for both the 1S0
and 3S1-3D1 channels.


title: The Triaxial Rotation Vibration Model in the Xe-Ba Region

abstract:
  The axial Rotation Vibration Model is here extended to describe also triaxial
equilibrium shapes with beta and gamma vibrations allowing for the interaction
between vibrations and rotations. This Triaxial Rotation Vibration Model (TRVM)
is applied to Xe and Ba isotopes with mass numbers between 120 and 130. This
area has recently been pointed out to be the O(6) limit of the Interacting
Boson Approximation (IBA). The present work shows that the TRVM can equally
well describe these nuclei concerning their excitation energies and E2
branching ratios.


title: Testing the Resolving Power of 2-D K^+ K^+ Interferometry

abstract:
  Adopting a procedure previously proposed to quantitatively study
two-dimensional pion interferometry, an equivalent 2-D chi^2 analysis was
performed to test the resolving power of that method when applied to less
favorable conditions, i.e., if no significant contribution from long lived
resonances is expected, as in kaon interferometry. For that purpose, use is
made of the preliminary E859 K^+ K^+ interferometry data from Si+Au collisions
at 14.6 AGeV/c. As expected, less sensitivity is achieved in the present case,
although it still is possible to distinguish two distinct decoupling
geometries. The present analysis seems to favor scenarios with no resonance
formation at the AGS energy range, if the preliminary K^+ K^+ data are
confirmed. The possible compatibility of data with zero decoupling proper time
interval, conjectured by the 3-D experimental analysis, is also investigated
and is ruled out when considering more realistic dynamical models with
expanding sources. These results, however, clearly evidence the important
influence of the time emission interval on the source effective transverse
dimensions. Furthermore, they strongly emphasize that the static Gaussian
parameterization, commonly used to fit data, cannot be trusted under more
realistic conditions, leading to distorted or even wrong interpretation of the
source parameters!


title: Equation of state and collision rate tests of parton cascade models

abstract:
  We develop two further numerical tests of parton cascade models: the ideal
gas equation of state and the collision frequency tests. The equation of state
test checks the initial momentum distribution generator and free expansion
dynamics in periodic inhomogeneous geometries. The collision rate test is
sensitive to spatial inhomogeneities and the collision algorithm. These tests
are applied to the recently developed ZPC parton cascade model. The tests
helped uncover unphysical correlations induced by one of the commonly used
random number generators and showed the necessity of particle subdivisions for
convergence to the exact analytic limit.


title:
Relativistic Mean Field Theory in Rotating Frame: Single-particle
  Properties at Superdeformation

abstract:
  Single-particle properties at superdeformation are investigated within the
Cranked Relativistic Mean Field (CRMF) theory on the example of superdeformed
rotational bands observed in the A~140-150 mass region. Applying the effective
alignment approach it is shown that CRMF theory provides a reasonable
description of the alignment properties of the single-particle orbitals. The
agreement with experiment is good in most of the cases. This suggests that many
features of the observed superdeformed bands can be well understood in terms of
an almost undisturbed single-particle motion. The stability of the results with
respect to the parameterizations used in Relativistic Mean Field (RMF) theory
is also investigated, employing some frequently used non-linear effective
forces. It turns out, with the exception of the single-particle ordering in
superdeformed minimum, that the dependence of the calculated observables on the
parameterization is rather small.


title:
Nuclear Effects In The F_3 Structure Function For Finite And Asymptotic
  Q^2

abstract:
  We study nuclear effects in the structure function F_3 which describes the
parity violating part of the charged-current neuitrino nucleon deep inelastic
scattering. Starting from a covariant approach we derive a factorized
expression for the nuclear structure function in terms of nuclear spectral
function and off-shell nucleon structure functions valid for arbitrary momentum
transfer Q and in the limit of weak nuclear binding, i.e. when a nucleus can be
treated as a non-relativistic system. We develop a systematic expansion of
nuclear structure functions in terms of Q^{-2} series caused by nuclear effects
("nuclear twist" series). Basing on this expansion we calculate nuclear
corrections to the Gross-Llewellyn-Smith sum rule as well as to higher moments
of F_3. We show that corrections to the GLS sum rule due to nuclear effects
cancel out in the Bjorken limit and calculate the corresponding Q^{-2}
correction. Special attention is payed to the discussion of the off-shell
effects in the structure functions. A sizable impact of these effects both on
Q^2- and x-dependence of nuclear structure functions is found.


title: Nonlinear collective nuclear motion

abstract:
  For each real number $\Lambda$ a Lie algebra of nonlinear vector fields on
three dimensional Euclidean space is reported. Although each algebra is
mathematically isomorphic to $gl(3,{\bf R})$, only the $\Lambda=0$ vector
fields correspond to the usual generators of the general linear group. The
$\Lambda < 0$ vector fields integrate to a nonstandard action of the general
linear group; the $\Lambda >0$ case integrates to a local Lie semigroup. For
each $\Lambda$, a family of surfaces is identified that is invariant with
respect to the group or semigroup action. For positive $\Lambda$ the surfaces
describe fissioning nuclei with a neck, while negative $\Lambda$ surfaces
correspond to exotic bubble nuclei. Collective models for neck and bubble
nuclei are given by irreducible unitary representations of a fifteen
dimensional semidirect sum spectrum generating algebra $gcm(3)$ spanned by its
nonlinear $gl(3,{\bf R})$ subalgebra plus an abelian nonlinear inertia tensor
subalgebra.


title: Coherent Vector Meson Production from Deuterons

abstract:
  In this paper we discuss coherent photo- and leptoproduction of vector mesons
from deuterons at intermediate (virtual) photon energies, 3 < nu < 30 GeV. We
consider the scattering from unpolarized and polarized targets as well as
processes where the polarization of the recoil deuteron is measured. Our main
motivation results from the need for a quantitative analysis of the space-time
structure of photon-induced processes. In this respect we suggest several
possibilities to explore the characteristic longitudinal interaction length in
coherent vector meson production. Furthermore, we outline methods for an
investigation of color coherence effects. In addition to the presentation of
benchmark values for the maximal possible color coherence effect in various
kinematic regions, we illustrate the anticipated phenomena within the color
diffusion model. Finally we recall that the determination of vector
meson-nucleon cross sections is not a closed issue. Besides being not known to
a satisfying accuracy, they can be used to determine the strength of the
D-state in low mass vector mesons.


title:
Total and Parity-Projected Level Densities of Iron-Region Nuclei by the
  Shell Model Monte Carlo Method

abstract:
  Total and parity-projected level densities of iron-region nuclei are
calculated microscopically by using Monte Carlo methods for the nuclear shell
model in the complete $(pf+0g_{9/2})$-shell. The calculated total level density
is found to be in good agreement with the experimental level density. The Monte
Carlo calculations offer a significant improvement over the thermal
Hartree-Fock approximation. Contrary to the Fermi gas model, it is found that
the level density has a significant parity-dependence in the neutron resonance
region. The systematics of the level density parameters (including shell
effects) in the iron region is presented.


title: Baryon flow at SIS energies

abstract:
  We calculate the baryon flow $< P_x/A(y) >$ in the energy range from .25 to
$\le 2.5 AGeV$ in a relativistic transport model for $Ni+Ni$ and $Au+Au$
collisions employing various models for the baryon self energies. We find that
to describe the flow data of the FOPI Collaboration the strength of the vector
potential has to be reduced at high relative momentum or at high density such
that the Schr\"odinger- equivalent potential at normal nuclear density
decreases above 1 GeV relative kinetic energy and approaches zero above 2 GeV.


title: Bremsstrahlung in Alpha-Decay

abstract:
  We present the first fully quantum mechanical calculation of photon radiation
accompanying charged particle decay from a barrier resonance. The soft-photon
limit agrees with the classical results, but differences appear at
next-to-leading-order. Under the conditions of alpha-decay of heavy nuclei, the
main contribution to the photon emission stems from Coulomb acceleration and
may be computed analytically. We find only a small contribution from the
tunneling wave function under the barrier.


title:
What Invariant One-Particle Multiplicity Distributions and Two-Particle
  Correlations Are Telling Us about Relativistic Heavy-Ion Collisions

abstract:
  We use a nine-parameter expanding source model that includes special
relativity, quantum statistics, resonance decays, and freeze-out on a realistic
hypersurface in spacetime to analyze invariant pi+, K+, and K- one-particle
multiplicity distributions and pi+ and pi- two-particle correlations in nearly
central collisions of Pb + Pb at a laboratory bombarding momentum per nucleon
of 158 GeV/c. The adjustable parameters of the model are determined by
minimizing chi-square with a total of 2137 data points for the five types of
data considered, which leads to an acceptable value of 1.017 for chi-square per
degree of freedom. Compared to earlier results obtained with this model for
nearly central collisions of Si + Au at a laboratory bombarding momentum per
nucleon of 14.6 GeV/c, the present results indicate that in Pb + Pb collisions
the freeze-out density is somewhat lower, the freeze-out temperature is
slightly higher, the source at freeze-out is somewhat larger, and the
longitudinal collective velocity is very poorly determined (because of the
limited experimental coverage in rapidity). For both reactions, the freeze-out
temperature is less than 100 MeV and the longitudinal and transverse collective
velocities-which are anti-correlated with the temperature-are substantial. We
reconcile these results with those in several previous analyses that yielded a
much higher freeze-out temperature of approximately 140 MeV, and finally
perform two additional studies with our expanding source model.


title:
The proton and neutron distribution in Na isotopes: the development of
  halo and shell structure

abstract:
  The interaction cross sections for $^A Na + ^{12}C$ reaction are calculated
using Glauber model. The continuum Hartree-Bogoliubov theory has been
generalized to treat the odd particle system and take the continuum into
account. The theory reproduces the experimental result quite well. The matter
distributions from the proton drip line to the neutron drip line in Na isotopes
have been systematically studied and presented. The relation between the shell
effects and the halos has been examined. The tail of the matter distribution
shows a strong dependence on the shell structure. The neutron N=28 closure
shell fails to appear due to the coming down of the $2p_{3/2}$ and $2p_{1/2}$.
The development of the halo was understood as changes in the occupation in the
next shell or the sub-shell close to the continuum limit. The central proton
density is found to be decreasing near the neutron drip line, which is due to
the proton-neutron interaction. However the diffuseness of the proton density
does not change for the whole Na isotopes.


title:
Antisymmetrized random phase approximation for quasielastic scattering
  in nuclear matter: Non-relativistic potentials

abstract:
  Many-body techniques for the calculation of quasielastic nuclear matter
response functions in the fully antisymmetrized random phase approximation on a
Hartree-Fock basis are discussed in detail. The methods presented here allow
for an accurate evaluation of the response functions with little numerical
effort. Formulae are given for a generic non-relativistic potential
parameterized in terms of meson exchanges; on the other hand, relativistic
kinematical effects have been accounted for.


title: Consequences of covariant kaon dynamics in heavy ion collisions

abstract:
  The influence of the chiral mean field on the kaon dynamics in heavy ion
reactions is investigated. Inside the nuclear medium the kaons are described as
dressed quasi-particles carrying effective masses and momenta. A momentum
dependent part of the interaction which resembles a Lorentz force originates
from spatial components of the vector field and provides an important
contribution to the in-medium kaon dynamics. This contribution is found to
counterbalance the influence of the vector potential on the $K^+$ in-plane flow
to a strong extent. Thus it appears to be difficult to restrict the in-medium
potential from the analysis of the corresponding transverse flow.


title: Isospin relaxation time in heavy-ion collisions at intermediate energies

abstract:
  Using an isospin-dependent transport model, we have studied the isospin and
momentum relaxation times in the heavy residues formed in heavy-ion collisions
at intermediate energies. It is found that only at incident energies below the
Fermi energy, chemical or thermal equilibrium can be reached before dynamical
instability is developed in the heavy residues. Also, the isospin relaxation
time is shorter (longer) than that for momentum at beam energies lower (higher)
than the Fermi energy.


title: Hadronic Observables: Theoretical Highlights

abstract:
  I present highlights from the parallel sessions on the theory of hadronic
observables in e^+ e^-, hadronic and nuclear reactions.


title: Algebraic treatment of the hyper-Coulomb problem

abstract:
  A completely algebraic treatment of the six-dimensional hypercoulomb problem
is discussed in terms of an oscillator realization of the dynamical algebra of
SO(7,2). Closed expressions are derived for the energy spectrum and form
factors.


title:
Spin Observables in Coincidence Electron Scattering from Nuclei I:
  Reduced Response Functions

abstract:
  A theoretical description of nucleon knockout reactions initiated by
polarized electron scattering from polarized nuclei is presented. Explicit
expressions for the complete set of reduced response functions (independent of
the polarization angle) that can be experimentally obtained assuming plane
waves for the electron are given in a general multipole expansion. The
formalism is applied to the particular case of closed-shell-minus-one nuclei
using two models for the ejected nucleon, including the final-state interaction
phenomenologically with a complex optical potential and in the factorized
plane-wave impulse approximation. Relativistic effects in the kinematics and in
the electromagnetic current are incorporated throughout --- specifically a new
expansion of the electromagnetic current in powers only of the struck nucleon
momentum is employed. Results are presented for the nucleus 39K.


title: Vector meson propagation in dense matter

abstract:
  The properties of vector mesons in nuclear matter are discussed. Results for
the momentum dependence of the $\rho$-meson self energy in matter due to $\rho
N$ interactions are presented, and consequences for the production rate of
$e^+e^-$ pairs in hot and dense matter are discussed. I also examine the
constraints imposed by elementary processes on the widths of $\rho$ and
$\omega$ mesons in nuclear matter, and conclude that in recent models the
in-medium widths of these mesons are overestimated.


title: Interacting boson models of nuclear and nucleon structure

abstract:
  Interacting boson models provide an elegant and powerful method to describe
collective excitations of complex systems by introducing a set of effective
degrees of freedom. We review the interacting boson model of nuclear structure
and discuss a recent extension to the nucleon and its excited states.


title: $\rho$-meson properties at finite nuclear density

abstract:
  We calculate the momentum dependence of the $\rho$-meson selfenergy based on
the dispersion relation for the $\rho N$ scattering amplitude $f(\omega$) at
low nuclear density. The imaginary part of $f(\omega)$ is determined from the
optical theorem, while the total $\rho N$ cross section is obtained within the
VDM at high energy and within the resonance model at low energy. Our numerical
results indicate a sizeable broadening of the $\rho$-meson width in the medium
especially for low relative momenta $p$ while the real part of the $\rho$
selfenergy is found to change its sign and becomes repulsive already at momenta
above 100 MeV/c. Extrapolating to nuclear saturation density $\rho_0$ we find a
dropping of the $\rho$-mass for $p \approx$ 0 in line with the QCD sumrule
analysis of Hatsuda while at high energy an increase of the $\rho$-mass in line
with the prediction by Eletsky and Joffe is obtained. However, when including a
broadening of the baryonic resonances in the medium, the $\rho$-meson mass
shift at $p \approx$ 0 becomes slightly repulsive whereas the width increases
substantially.


title: Self-consistent methods in nuclear structure physics

abstract:
  We present a very brief description of the Hartree-Fock method in nuclear
structure physics, discuss the numerical methods used to solve the
self-consistent equations, and analyze the precision and convergence properties
of solutions. As an application we present results pertaining to quadrupole
moments and single-particle quadrupole polarizations in superdeformed nuclei
with A~60.


title:
Comment on ``Evidence for Narrow Baryon Resonances in Inelastic pp
  Scattering''

abstract:
  Compton scattering data are sensitive to the existence of low-mass resonances
reported by Tatischeff et al. We show that such states, with their reported
properties, are excluded by previous Compton scattering experiments.


title: Anisotropy as a Consequence of Pre-equilibrium Rescattering

abstract:
  It is shown that azimuthal asymmetry in transverse momentum distribution of
particles observed in non-central heavy ion collisions can originate from
pre-equilibrium rescattering. The phenomenon is studied using computer
simulation of expanding pion gas created in Pb+Pb 160 GeV/n collisions. Results
obtained are discussed in comparison with experimental results of NA49
collaboration. Theoretical understanding of mechanism generating the asymmetry
is presented. Conclusion about non-equilibrium properties of the phenomenon
studied is drawn.


title: Chemical potential dependence of pi and rho properties

abstract:
  Using a confining, Dyson-Schwinger equation model of QCD at finite
temperature (T) and chemical potential (mu) we study the behaviour of <q-bar
q>, m_pi, f_pi and the masses of the rho- and phi-mesons. For each of these
quantities there is a necessary anticorrelation between its response to T and
its response to mu. (-<q-bar q>) and f_pi decrease with T and increase with mu;
m_pi is almost insensitive to T and mu until very near the border of the
confinement domain; and the mass of the longitudinal component of the vector
mesons increases with T and decreases with mu. At T=0, the rho-meson mass is
reduced by approximately 15% at nuclear matter density. These results are a
consequence of the necessary momentum-dependence of the dressed-quark
self-energy.


title: A dynamical, confining model and hot quark stars

abstract:
  We explore the consequences of an equation of state (EOS) obtained in a
confining Dyson-Schwinger equation model of QCD for the structure and stability
of nonstrange quark stars at finite-T, and compare the results with those
obtained using a bag-model EOS. Both models support a temperature profile that
varies over the star's volume and the consequences of this are model
independent. However, in our model the analogue of the bag pressure is
(T,mu)-dependent, which is not the case in the bag model. This is a significant
qualitative difference and comparing the results effects a primary goal of
elucidating the sensitivity of quark star properties to the form of the EOS.


title: The Spectral Density of the Dirac Operator above T_c

abstract:
  The importance of the spectral density of the Dirac operator in studying
spontaneous chiral symmetry breaking and anomalous U(1) axial symmetry breaking
are reviewed. It is shown that both types of symmetry breaking can be traced to
effects of modes near zero virtuality. Above T_c, where chiral symmetry is
restored, it is shown on general grounds that (in the massless quark limit),
the density of states vanishes at zero virtuality faster than $\lambda$, where
$\lambda$ is the virtuality-- $\rho(\lambda) \sim |\lambda|^\alpha$ is not
possible for $\alpha \le 1$. Isospin invariance is used to show that
$\rho(\lambda) \sim m_q^{1-\alpha} |\lambda|^\alpha$ is also not possible for
$\alpha \le 1$. State-of-the-art lattice calculations are reviewed in light of
these constraints. In particular, it is argued that violations of these
constraints by lattice calculations indicate possible large systematic errors;
this raises questions about $U(1)_A$ violating effects seen on the lattice.It
is also shown that above $T_c$, the Dirac spectrum has a gap near zero (in the
$m_q \to 0$ limit) unless contributions from quark-line-connected and
disconnected contributions conspire to cancel.


title: Physics of Strange Matter

abstract:
  The properties of strange quark matter and strange hadronic matter and their
finite counterparts (strangelets and MEMOs) are reviewed. The production of
strange matter in heavy-ion collision and the appearance of strange matter in
neutron stars are discussed.


title:
Resonance model study of kaon production in baryon baryon reactions for
  heavy ion collisions

abstract:
  The energy dependence of the total kaon production cross sections in baryon
baryon ($N$ and $\Delta$) collisions are studied in the resonance model, which
is a relativistic, tree-level treatment. This study is the first attempt to
complete a systematic, consistent investigation of the elementary kaon
production reactions for both the pion baryon and baryon baryon reactions. Our
model suggests that the magnitudes of the isospin-averaged total cross sections
for the $N N \to N Y K$ and $\Delta N \to N Y K$ ($Y = \Lambda$ or $\Sigma$)
reactions are almost equal at energies up to about 200 MeV above threshold.
However, the magnitudes for the $\Delta N$ reactions become about 6 times
larger than those for the $N N$ reactions at energies about 1 GeV above
threshold. Furthermore, the magnitudes of the isospin-averaged total cross
sections for the $N N \to \Delta Y K$ reactions turn out to be comparable to
those for the $N N \to N Y K$ reactions at $N N$ invariant collision energies
about 3.1 GeV, and about 5 to 10 times larger at $N N$ invariant collision
energies about 3.5 GeV. The microscopic cross sections are parametrized in all
isospin channels necessary for the transport model studies of kaon production
in heavy ion collisions. These cross sections are then applied in the
relativistic transport model to study the sensitivity to the underlying
elementary kaon production cross sections.


title:
Nuclear forces from chiral Lagrangians using the method of unitary
  transformation I: Formalism

abstract:
  We construct the two- and three-nucleon potential based on the most general
chiral effective pion-nucleon Lagrangian using the method of unitary
transformations. For that, we develop a power counting scheme consistent with
this projection formalism. In contrast to previous results obtained in
old-fashioned time-ordered perturbation theory, the method employed leads to
energy-independent potentials. We discuss in detail the similarities and
differences to the existing chiral nucleon-nucleon potentials. We also show
that to leading order in the power counting, the three-nucleon forces vanish
lending credit to the result obtained by Weinberg using old-fashioned
time-ordered perturbation theory.


title:
Double $\Lambda$ Hypernuclei and the Nuclear Medium Effective
  $\Lambda\Lambda$ Interaction

abstract:
  We fit the $^1 S_0 \Lambda\Lambda$ interaction in the nuclear medium to the
masses of the experimentally known double-$\Lambda$ hypernuclei:
$^{\phantom{6}6}_{\Lambda\Lambda}$He, $^{10}_{\Lambda\Lambda}$Be and
$^{13}_{\Lambda\Lambda}$B. We derive this effective interaction from OBE
J\"ulich $\Lambda\Lambda$-type potentials and using both Hartree-Fock and
variational approaches. We find that the inclusion of $\Lambda\Lambda$
correlations in the variational scheme leads to significant differences and a
better understanding of the dynamical features of the system. We investigate
the sensitivity of the binding energies and the mesonic decay widths of the
above double-$\Lambda$ hypernuclei to the $\omega \Lambda\Lambda $ coupling and
the form factor at the $\sigma \Lambda\Lambda$ vertex.
  We also use this effective interaction to predict binding energies and pionic
decay widths of heavier double-$\Lambda$ hypernuclei, not discovered yet.
Finally, we discard the existence of $^1 S_0$ $\Lambda\Lambda$ bound states
provided the $\Lambda\Lambda-\Xi N$ coupling can be neglected.


title: Semi-relativistic charge-current density operator

abstract:
  The charge-current density and two-photon operators consistent with a
single-particle semi-relativistic Hamiltonian are derived within a suitable
functional derivative formalism which preserves gauge invariance. An
application to electron scattering is presented and results are compared with a
fully relativistic case and the non-relativistic cases corrected through fourth
order in M^{-1}.


title: Nonperturbative Flow Equations at Finite Temperature

abstract:
  Nonperturbative Flow Equations within an effective constituent quark model
for two quark flavors with Heat-Kernel methods are studied.


title:
Excitation function of entropy and pion production from AGS to SPS
  energies

abstract:
  Entropy production in the initial compression stage of relativistic heavy-ion
collisions from AGS to SPS energies is calculated within a three-fluid
hydrodynamical model. The entropy per participating net baryon is found to
increase smoothly and does not exhibit a jump or a plateau as in the
1-dimensional one-fluid shock model. Therefore, the excess of pions per
participating net baryon in nucleus-nucleus collisions as compared to
proton-proton reactions also increases smoothly with beam energy.


title: Theoretical Interpretation of Low-Mass Dileptons

abstract:
  An overview is given of chiral symmetry restoration at finite temperature and
baryochemical potential. Within hadronic models of the vector correlator its
implications for low-mass dilepton spectra in ultrarelativistic heavy-ion
collisions are discussed.


title: Freeze-out from HBT and Coulomb Effects

abstract:
  The freeze-out of hot and dense hadronic matter formed in relativistic
nuclear collisions is probed by HBT interferometry of identical pions, kaons,
etc. Coulomb repulsion/attraction of positive/negative particles show up at
small particle momenta and is also very sensitive to the freeze-out conditions.
The source sizes and times freeze-out are extracted from $\pi^-/\pi^+$ spectra
and HBT radii and compared.


title: Effects of B-8 size on the low-energy Be7(p,gamma)B8 cross section

abstract:
  We calculate several "size-like" B-8 observables within the microscopic
three-cluster model and study their potential constraints on the zero-energy
astrophysical S_{17}(0) factor of the Be7(p,gamma)B8 reaction. We find within
our three-cluster model that a simultaneous reproduction of the experimental
data for the B-8 radius and quadrupole moment and of the B8-Li8 Coulomb
displacement energy implies S_{17}(0)=(23-25) eVb.


title:
Large-space cluster model calculations for the He3(He3,2p)He4 and
  H3(H3,2n)He4 reactions

abstract:
  The He3(He3,2p)He4 and H3(H3,2n)He4 reactions are studied in a microscopic
cluster model. We search for resonances in the He3+He3 and He4+p+p channels
using methods that treat the two- and three-body resonance asymptotics
correctly. Our results show that the existence of a low-energy resonance or
virtual state, which could influence the Be-7 and B-8 solar neutrino fluxes, is
rather unlikely. Our calculated He3(He3,2p)He4 and H3(H3,2n)He4 cross sections
are in a good general agreement with the experimental data.


title:
Effective two-body interactions in the s-d shell nuclei from sum rules
  equations in tranfer reactions

abstract:
  Average effective two-body interaction matrix elements in the s-d shell have
been extracted, from data on experimentally measured isospin centroids, by
combining the recently derived new sum rules equations for pick-up reactions
with similar known equations for stripping reactions performed on general
multishell target states. Using this combination of stripping and pick-up
equations, the average effective matrix elements for the shells, 1d^2_5/2,
2s^2_1/2 and 1d^2_3/2 respectively have been obtained. A new feature of the
present work is that the restriction imposed in earlier works on target states,
that it be populated only by active neutrons has now been abandoned.


title: Non-Central Heavy-Ion Collisions are the Place to Look for DCC

abstract:
  We give two reasons why we believe that non-central ultrarelativistic heavy
ion collisions are the place to look for the disoriented chiral condensates
(DCC). First, we argue that the most probable quench scenario for the formation
of DCC requires non-central collisions. Second, we show by numerical
simulations that strong electromagnetic fields of heavy ions can exert a
surprisingly large effect on the DCC domain formation through the chiral
anomaly. The effect again requires non-central collisions. Interestingly, the
result of simulations is consistent with the formation of correlated two
domains of the chiral condensate, which are aligned in space, perpendicular to
the scattering plane, but misaligned in isospin space.


title:
Pauli coupling of vector meson and softening of the nuclear equation of
  state

abstract:
  We investigate the equation of state (EOS) for nuclear matter, within the
framework of the Relativistic Hartree Fock (RHF) theory, with special emphasis
on the role of the Pauli coupling of the vector meson $\rho$ to the nucleon
vis-a-vis the eventual softening of the EOS as revealed through a substantial
reduction of the incompressibility parameter ($K_0$) for symmetric nuclear
matter.


title: Nuclear breakup of $^8$B in a direct fragmentation model

abstract:
  We calculate the cross sections of the elastic and inelastic breakup modes
for the inclusive breakup reaction $^{28}$Si($^8$B,$^7$Be) at beam energies
between 10 - 40 MeV/nucleon within a direct fragmentation model formulated in
the framework of the post form distorted-wave Born-approximation. In contrast
to the case of the stable isotopes, the inelastic breakup mode is found to
contribute only upto 30% to the total breakup cross section, which is in
agreement with the recently measured experimental data. However, the high
energy tail of the energy spectra of $^7$Be fragment is dominated by the
inelastic breakup mode. The breakup amplitude is found to be dominated by the
contributions from distrances well beyond the nuclear surface.


title:
Compactness of the set of Faddeev and Lippmann--Schwinger equations for
  the three-body Coulomb problem

abstract:
  The set of Faddeev and Lippmann--Schwinger integral equations for three-body
systems involving Coulomb interactions deduced from a ``three-potential''
picture are shown to be compact for all energies and a method of solution is
given.


title:
Pion Electroproduction and Pion-induced Dileptonproduction on the
  Nucleon

abstract:
  By introducing electromagnetic formfactors in the spacelike region we extend
an effective, gauge invariant Lagrangian model considering Born terms, baryon
resonances up to 1.7 GeV and vector meson contributions (Rho, Omega) to
calculate electroproduction of Pi-mesons. This model forms the basis for
predictions of pion induced dilepton production on the nucleon. Therefore, the
implemented formfactors are constructed in such a way that their analytic
continuation into the timelike region is possible. It is shown that the seagull
term and the N*(1520) resonance play a dominant role in the dilepton
production.


title: Electric polarizability of nuclei from a longitudinal sum rule

abstract:
  The nuclear electric polarizability is theoretically analyzed using a sum
rule derived from the longitudinal part of the forward Compton amplitude.
Beyond the leading dipole contribution, this approach leads to the presence of
potential-dependent terms that do not show up in previous analyses. The
significance of these new contributions is illustrated by performing an
explicit calculation for a proton-neutron system interacting via a separable
potential.


title:
Computation of Two-Body Matrix Elements From the Argonne $v_{18}$
  Potential

abstract:
  We discuss the computation of two-body matrix elements from the Argonne
$v_{18}$ interaction. The matrix elements calculation is presented both in
particle-particle and in particle-hole angular momentum coupling. The
procedures developed here can be applied to the case of other NN potentials,
provided that they have a similar operator format.


title: Production of $\omega$-mesons in proton-proton collisions

abstract:
  The production of $\omega$-mesons in proton-proton collisions for proton
incident energies up to 2.2 GeV is investigated within a meson-exchange model
of hadronic interactions.
  We find a large cancellation between the dominant $\pi\rho\omega$
meson-exchange current and nucleonic current contributions. A comparison with
preliminary data from SATURNE calls for the inclusion of off-shell form factors
at the $NN\omega$ and $\pi\rho\omega$ production vertices. Due to the present
lack of knowledge of these form factors, together with the destructive
interference mentioned above, the relative magnitude of the nucleonic and
meson-exchange current contributions cannot be determined from existing total
cross section data. However, it is shown that the angular distribution of the
produced $\omega$-mesons provides an unique and clear signature of the
magnitude of these currents, thus allowing one to disentangle these two basic
reaction mechanisms.


title:
Shell corrections for finite depth potentials: Particle continuum
  effects

abstract:
  Shell corrections of finite, spherical, one-body potentials are analyzed
using a smoothing procedure which properly accounts for the contribution from
the particle continuum, i.e., unbound states. Since the plateau condition for
the smoothed single-particle energy seldom holds, a new recipe is suggested for
the definition of the shell correction. The generalized Strutinsky smoothing
procedure is compared with the results of the semi-classical Wigner-Kirkwood
expansion. A good agreement has been found for weakly bound nuclei in the
vicinity of the proton drip line. However, some deviations remain for extremely
neutron-rich systems due to the pathological behavior of the semi-classical
level density around the particle threshold.


title: Partons in Phase Space

abstract:
  Within QED, we examine several issues related to constructing a
parton-model-based QCD transport theory. We rewrite the QED analog of the
parton model, the Weizsaecker-Williams Approximation, entirely in terms of
phase-space quantities and we study the phase-space photon and electron
densities created by a classical point charge. We find that the densities take
a distinctive ``source-propagator'' form. This form does not arise in a
conventional derivation of the semiclassical transport equations because of the
overuse of the gradient approximation. We do not apply the gradient
approximation and so derive the phase-space analog of the Generalized
Fluctuation-Dissipation Theorem. Together, this theorem and the expression for
the phase-space particle self-energies give a set of coupled phase-space
evolution equations. We illustrate how these evolution equations can be used
perturbatively or to derive semiclassical transport equations. Our work relies
on phase-space propagators and sources, so we describe them in detail when
calculating the photon and electron phase-space densities. We use these tools
to discuss the shape of a nucleon's parton cloud.


title: A Parton-Hadron Cascade Approach in High-energy Nuclear Collisions

abstract:
  A parton-hadron cascade model which is the extension of hadronic cascade
model incorporating hard partonic scattering based on HIJING is presented to
describe the space-time evolution of parton/hadron system produced by
ultra-relativistic nuclear collisions. Hadron yield, baryon stopping and
transverse momentum distribution are calculated and compared with HIJING and
VNI.


title: Unified model of the relativistic piNN and gamma-piNN systems

abstract:
  We present a unified description of the relativistic piNN and gamma-piNN
systems where the strong interactions are described non-perturbatively by
four-dimensional integral equations. Our formulation obeys two and three-body
unitarity and is strictly gauge invariant with photons coupled to all possible
places in the strong interaction model. At the same time our formulation is
free from the overcounting problems plaguing four-dimensional descriptions of
piNN and gamma-piNN systems. The accurate nature of our description is achieved
through the use of the recently introduced gauging of equations method.


title: A Mixed Phase Model and the 'Softest Point' Effect

abstract:
  Particularities of the statistical mixed phase model for describing the
deconfinement phase transition and physics constraints on the model parameters,
are discussed. The modifications proposed concern an improved treatment of
hadron-hadron interactions within the nonlinear mean-field model of nuclear
matter and an inclusion of the one-gluon exchange correction into the
quark-gluon sector of the mixed phase thermodynamic potential. It is shown that
the mixed phase model successfully reproduces both the available lattice data
on the QCD deconfinement transition and thermodynamic characteristics of hadron
systems evaluated within the modern models. The 'softest point' of the equation
of state resulting in a possible formation of a long-lived fireball in nuclear
collisions (the 'softest point' effect) is analyzed. The obtained results are
confronted with the data on the two-phase model. Some manifestation of the
mixed phase formation and deconfinement transition is estimated in fireball
expansion dynamics. We discuss experimental possibilities of observing the
softest point effect as a signal of the deconfinement phase transition.


title: Strangeness production in proton-proton collisions

abstract:
  The cross sections of the reaction $pp \to N K Y$ for $K^+$ or $K^0$ mesons
and $\Lambda$ or $\Sigma$ hyperons are calculated within the boson exchange
model including pion and kaon exchange diagrams. We analyze the dependence of
the results on the accuracy of the input $\pi N$ amplitude. By fixing the $\pi
NN $ coupling constant and the cut-off parameter ${\Lambda}_{\pi}$ at the $\pi
NN$ vertex we calculate the contribution from the kaon exchange diagram and
obtain the ratio of the $KN \Lambda $ and $KN \Sigma $ coupling constants by a
fit to the experimental data. This ratio is in a good agreement with the SU(6)
prediction. Our calculated total cross sections for the different reaction
channels are fitted by simple expressions and compared with other
parameterizations used in the literature. Furthermore, the gross features of
the production cross section close to threshold are discussed.


title:
Deep inelastic scattering and final state interaction in an exactly
  solvable relativistic model

abstract:
  In the theory of deep inelastic scattering (DIS) the final state interaction
(FSI) between the struck quark and the remnants of the target is usually
assumed to be negligible in the Bjorken limit. This assumption, still awaiting
a full validation within nonperturbative QCD, is investigated in a model
composed by two relativistic particles, interacting via a relativistic harmonic
oscillator potential, within light-cone hamiltonian dynamics. An
electromagnetic current operator whose matrix elements behave properly under
Poincar\'e transformations is adopted. It is shown that: i) the parton model is
recovered, once the standard parton model assumptions are adopted; and ii) when
relativistic, interacting eigenfunctions are exactly taken into account for
both the initial and final states, the values of the structure functions,
averaged over small, but finite intervals of the Bjorken variable $x$, coincide
with the results of the parton model in the Bjorken limit.


title:
Transport theory with self-consistent confinement related to the lattice
  data

abstract:
  The space-time development of a quark-gluon plasma is calculated from a
Vlasov equation for the distribution function of quasiparticles with medium
dependent masses. At each space-time point the masses are calculated
selfconsistently from a gap equation, whose form is determined by the
requirement that in thermal equilibrium and for a range of temperatures the
energy density of the quasi-particle system is identical to the one from
lattice calculations . The numerical solutions of the Vlasov equation display
confinement. Relations to effective theories like that by Friedberg Lee and
Nambu Jona-Lasinio are established.


title: Solution of Integral Equations by a Chebyshev Expansion Method

abstract:
  A new spectral type method for solving the one dimensional quantum-mechanical
Lippmann-Schwinger integral equation in configuration space is described. The
radial interval is divided into partitions, not necessarily of equal length.
Two independent local solutions of the integral equation are obtained in each
interval via Clenshaw-Curtis quadrature in terms of Chebyshev Polynomials. The
local solutions are then combined into a global solution by solving a matrix
equation for the coefficients. This matrix is sparse and the equation is easily
soluble. The method shows excellent numerical stability, as is demonstrated by
several numerical examples.


title:
Inclusion of virtual nuclear excitations in the formulation of the
  (e,e'N)

abstract:
  A wave-function framework for the theory of the (e,e'N) reaction is presented
in order to justify the use of coupled channel equations in the usual Feynman
matrix element. The overall wave function containing the electron and nucleon
coordinates is expanded in a basis set of eigenstates of the nuclear
Hamiltonian, which contain both bound states as well as continuum states.. The
latter have an ingoing nucleon with a variable momentum Q incident on the
daughter nucleus as a target, with as many outgoing channels as desirable. The
Dirac Eqs. for the electron part of the wave function acquire inhomogeneous
terms, and require the use of distorted electron Green's functions for their
solutions. The condition that the asymptotic wave function contain only the
appropriate momentum Q_k for the outgoing nucleon, which corresponds to the
electron momentum k through energy conservation, is achieved through the use of
the steepest descent saddle point method, commonly used in three-body
calculations.


title:
Low-energy photodisintegration of 9Be and alpha + alpha + n <-> 9Be +
  gamma reactions at astrophysical conditions

abstract:
  A semi-microscopic model for the low-energy photodisintegration of the 9Be
nucleus is constructed, and the experimental data are analyzed with its help.
The older radioactive isotope data are supported by this analysis. The
theoretical photodisintegration cross section is derived. The astrophysical
rates for the reaction alpha + alpha + n -> 9Be + gamma and the reverse
photodisintegration of 9Be are calculated. The new reaction rate for alpha +
alpha + n -> 9Be + gamma is compared with previous estimations.


title:
Final State Interactions in the Near-Threshold Production of Kaons from
  Proton-Proton Collisions

abstract:
  We analyse the $pp \to p \Lambda K$ cross section recently measured at COSY
arguing that the enhancement of the production cross section at energies close
to the reaction threshold should be due to the $\Lambda p$ final state
interaction. We find that the experimental $\Lambda p$ elastic scattering data
as well as the predictions from the J\"ulich-Bonn model are in reasonable
agreement with the new results on $K^+$-meson production. We propose to study
directly the final state interaction by measurements of the cross section as a
function of the hyperon momentum in the $\Lambda p$ cm system.


title:
Global Transmission Coefficients in Hauser-Feshbach Calculations for
  Astrophysics

abstract:
  The current status of optical potentials employed in the prediction of
thermonuclear reaction rates for astrophysics in the Hauser-Feshbach formalism
is discussed. Special emphasis is put on $\alpha$+nucleus potentials. A novel
approach for the prediction of $\alpha$+nucleus potentials is proposed. Further
experimental efforts are motivated.


title:
Cascade-Exciton Model Analysis of Nucleon-Induced Fission Cross Sections
  of Lead and Bismuth at Energies from 45 to 500 MeV

abstract:
  An extended version of the Cascade-Exciton Model (CEM) of nuclear reactions
is applied to analyze nucleon-induced fission cross sections for Bi-209 and
Pb-208 nuclei in the 45-500 MeV energy range. The available data on linear
momentum transfer are analyzed as well. The results are compared with
analytical approximations resulting from a comparative critical analysis of all
available experimental data. Systematic discrepancies between calculations and
experimental data are revealed. A modification of the CEM is proposed, which
significantly improves the model predictions for projectile energies above 100
MeV.


title: Direct capture astrophysical S factors at low energy

abstract:
  We investigate the energy dependence of the astrophysical S factors for the
reactions 7Be(p,gamma)8B, the primary source of high-energy solar neutrinos in
the solar pp chain, and 16O(p,gamma)17F, an important reaction in the CNO
cycle. Both of these reactions have predicted S factors which rise at low
energies; we find the source of this behavior to be a pole in the S factor at a
center-of-mass energy E = -E_B, the point where the energy of the emitted
photon vanishes. The pole arises from a divergence of the radial integrals.


title: Ground state correlations and mean-field in $^{16}$O

abstract:
  We use the coupled cluster expansion ($\exp(S)$ method) to generate the
complete ground state correlations due to the NN interaction. Part of this
procedure is the calculation of the two-body G matrix inside the nucleus in
which it is being used. This formalism is being applied to $^{16}O$ in a
configuration space of 50 $\hbar\omega$. The resulting ground state wave
function is used to calculate the binding energy and one- and two-body
densities for the ground state of $^{16}O$.


title: Strange Phases in Neutron Stars

abstract:
  The equation of state and the properties of neutron stars are studied for a
phase transition to a charged kaon condensate. We study the mixed phase by
using Gibbs condition with comparison to the hitherto applied Maxwell
construction. Implications for kaon condensation and for the mass-radius
relation of condensed neutron stars are examined.


title: Ground state correlations and mean field using the exp(S) method

abstract:
  This document gives a detailed account of the terms used in the computation
of the ground state mean field and the ground state correlations. While the
general approach to this description is given in a separate paper
(nucl-th/9802029) we give here the explicite expressions used.


title: Center-of-mass corrections revisited: a many-body expansion approach

abstract:
  A many-body expansion for the computation of the charge form factor in the
center-of-mass system is proposed. For convergence testing purposes, we apply
our formalism to the case of the harmonic oscillator shell model, where an
exact solution exists. We also work out the details of the calculation
involving realistic nuclear wave functions. Results obtained for the Argonne
$v$18 two-nucleon and Urbana-IX three-nucleon interactions are reported. No
corrections due to the meson-exchange charge density are taken into account.


title: Dynamics of kaons in nuclear matter

abstract:
  We consider $K^-$ nucleon elastic and inelastic scattering in isospin
symmetric nuclear matter. It is found that the proper description of the
$\Lambda(1405)$ resonance structure in nuclear matter requires a
self-consistent approach. Then the $\Lambda (1405) $ resonance mass remains
basically unchanged, however, the resonance acquires an increased decay width
as nuclear matter is compressed. The elastic and inelastic scattering
amplitudes show important medium modifications close to the kaon nucleon
threshold. We also construct the $K^-$-nuclear optical potential appropriate
for $K^-$ atoms. Our microscopic approach predicts a strong attractive
non-local interaction strength.


title: Flash of photons from the early stage of heavy-ion collisions

abstract:
  The dynamics of partonic cascades may be an important aspect for particle
production in relativistic collisions of nuclei at CERN SPS and BNL RHIC
energies. Within the Parton-Cascade Model, we estimate the production of single
photons from such cascades due to scattering of quarks and gluons q g -> q
gamma, quark-antiquark annihilation q qbar -> g gamma, or gamma gamma, and from
electromagnetic brems-strahlung of quarks q -> q gamma. We find that the latter
QED branching process plays the dominant role for photon production, similarly
as the QCD branchings q -> q g and g -> g g play a crucial role for parton
multiplication. We conclude therefore that photons accompanying the parton
cascade evolution during the early stage of heavy-ion collisions shed light on
the formation of a partonic plasma.


title: Exactly solvable models of baryon structure

abstract:
  We present a qualitative analysis of the gross features of baryon
spectroscopy (masses and form factors) in terms of various exactly solvable
models. It is shown that a collective model, in which baryon resonances are
interpreted as rotations and vibrations of an oblate symmetric top, provides a
good starting point for a more detailed quantitative study.


title: Baryon Junction Stopping at the SPS and RHIC via HIJING/B

abstract:
  Baryon stopping at the SPS and RHIC energies is calculated by introducing a
new baryon junction mechanism into HIJING. The exchange of a baryon junction,
according to Regge phenomenology, leads to a cosh(y/2) rapidity dependence and
an s^(-1/4) energy dependence of the inclusive baryon cross section. This
baryon junction dynamics also leads naturally to enhanced p_T broadening in pA
and AA together with enhanced mid-rapidity hyperon production.


title: Theoretical Interpretations of J/Psi Suppression: A Summary

abstract:
  The strong "anomalous" J/Psi suppression observed recently by the NA50
Collaboration at CERN SPS has attracted considerable attention. Is it the first
signature of a long-awaited quark-gluon plasma, or just a peculiar combination
of "conventional" effects acting together to produce the puzzling pattern
observed experimentally? This talk is an attempt to summarize the theoretical
explanations proposed during the last two years.


title: Chiral Perturbation Theory Approach to NN Scattering Problem

abstract:
  It is shown that chiral perturbation theory (in its original form by
Weinberg) can describe NN scattering with positive as well as negative
effective range. Some issues connected with unnaturally large NN ^1S_0
scattering length are discussed.


title:
Consistent description of NN and pi-N interactions using the solitary
  boson exchange potential

abstract:
  A unified description of NN and pi-N elastic scattering is presented in the
framework of the one solitary boson exchange potential (OSBEP). This model
already successfully applied to analyze NN scattering is now extended to
describe pi-N scattering while also improving its accuracy in the NN domain. We
demonstrate the importance of regularization of pi-N scattering amplitudes
involving Delta isobars and derivative meson-nucleon couplings, as this model
always yields finite amplitudes without recourse to phenomenological form
factors. We find an empirical scaling relation of the meson self interaction
coupling constants consistent with that previously found in the study of NN
scattering. Finally, we demonstrate that the OSBEP model does not contradict
the soft-pion theorems of pi-N scattering.


title: Global statistical model calculations and the role of isospin

abstract:
  An improved code for the calculation of astrophysical reaction rates in the
statistical model is presented. It includes the possibility to study isospin
effects. Such effects heavily affect capture rates involving self-conjugate
nuclei and may also be found in reactions on other intermediate and heavy
targets.


title: State-dependent Jastrow correlation functions for 4He nuclei

abstract:
  We calculate the ground-state energy for the nucleus 4He with V4 nucleon
interactions, making use of a Jastrow description of the corresponding
wavefunction with state-dependent correlation factors. The effect related to
the state dependence of the correlation is quite important, lowering the upper
bound for the ground-state energy by some 2 MeV.


title: An improvement on RPA based on a Boson mapping

abstract:
  We use a solvable model to perform modified dyson mapping and reveal the
unphysical-state effects in the original Random Phase Approximation (RPA). We
then propose a method to introduce the RPA and improve it based on a Boson
mapping.


title: Electromagnetic decays of vector mesons as derived from QCD sum rules

abstract:
  We apply the method of QCD sum rules in the presence of external
electromagnetic fields $F_{\mu\nu}$ to the problem of the electromagnetic
decays of various vector mesons, such as $\rho\to\pi\gamma$, $K^\ast\to
K\gamma$ and $\eta'\to\rho\gamma$. The induced condensates obtained previously
from the study of baryon magnetic moments are adopted, thereby ensuring the
parameter-free nature of the present calculation. Further consistency is
reinforced by invoking various QCD sum rules for the meson masses. The
numerical results on the various radiative decays agree very well with the
experimental data.


title: The APEX/EPOS Quandary: the Way Out via Low Energy Studies

abstract:
  A scorecard summary of the various data of the ``Sharp Lepton Problem'' is
presented. The present situation, in which APEX reports ``...no evidence for
sharp pairs...'' even as their data exhibits a sharp pair excess near 800 keV,
is discussed. Two kinds of low energy experiments utilizing non-heavy ion
processes are suggested as means to break the impasse arising from the
ambiguity of the present heavy ion data.


title:
Onset of T=0 Pairing and Deformations in High Spin States of the N=Z
  Nucleus 48Cr

abstract:
  The yrast line of the N=Z nucleus 48Cr is studied up to high spins by means
of the cranked Hartree-Fock-Bogoliubov method including the T=0 and T=1 isospin
pairing channels. A Skyrme force is used in the mean-field channel together
with a zero-range density-dependent interaction in the pairing channels. The
extensions of the method needed to incorporate the neutron-proton pairing are
summarized. The T=0 pairing correlations are found to play a decisive role for
deformation properties and excitation energies above 16hbar which is the
maximum spin that can be obtained in the f7/2 subshell.


title: Canonical Strangeness Enhancement

abstract:
  According to recent experimental data and theoretical developments we discuss
three distinct topics related to strangeness enhancement in nuclear reactions.
We investigate the compatibility of multi-strange particle ratios measured in a
restricted phase space with thermal model parameters extracted recently in 4pi.
We study the canonical suppression as a possible reason for the observed
strangeness enhancement and argue that a connection between QGP formation and
the undersaturation of strangeness is not excluded.


title: Pairing and the structure of the pf-shell N ~ Z nuclei

abstract:
  The influence of the isoscalar and isovector L=0 pairing components of the
effective nucleon-nucleon interaction is evaluated for several isobaric chains,
in the framework of full pf shell model calculations. We show that the combined
effect of both isospin channels of the pairing force is responsible for the
appearance of T=1 ground states in N=Z odd-odd nuclei. However, no evidence is
found relating them to the Wigner energy. We study the dependence of their
contributions to the total energy on the rotational frecuency in the deformed
nucleus 48Cr. Both decrease with increasing angular momentum and go to zero at
the band termination. Below the backbending their net effect is a reduction of
the moment of inertia, more than half of which comes from the proton-neutron
channel.


title: Many-body theory of nuclear and neutron star matter

abstract:
  We present results obtained for nuclei, nuclear and neutron star matter, and
neutron star structure obtained with the recent Argonne v18 two- nucleon and
Urbana IX three-nucleon interactions including relativistic boost corrections.
These interactions predict that matter will undergo a transition to a spin
layered phase with neutral pion condensation. We also consider the possibility
of a transition to quark matter.


title:
Mesons in Nuclei in the Light-Front Mean Field Approximation and
  Deep-Inelastic Scattering

abstract:
  A light-front treatment for the scalar and vector meson momentum distribution
functions is developed using a model in which the nucleus is treated a static
source of radius $R$. The limit $R\to \infty$ corresponds to infinite nuclear
matter. In this limit, the scalar mesons are shown to carry a vanishing
momentum fraction of the nuclear plus momentum $k^+$, but the vector mesons
carry a significant fraction, all occuring at the experimentally inaccessible
value of $k^+=0$. This confirms earlier work. A study of the $R$ dependence for
sizes of real nuclei shows that a fraction of the scalar and vector mesons
could be observable.


title: Solar Neutrinos: Where We Are, What We Need

abstract:
  This talk compares standard model predictions with the results of solar
neutrino experiments. Here `standard model' means the combined standard model
of minimal electroweak theory plus a standard solar model. I emphasize the
importance of recent analyses in which the neutrino fluxes are treated as free
parameters, independent of any constraints from solar models, and the stunning
agreement between the predictions of standard solar models and
helioseismological measurements. In order to interpret solar neutrino
experiments more accurately in terms of fundamental physics and astronomy, we
need improved improved nuclear physics data. I describe the five most important
nuclear physics problems whose solution is required for understanding the
precise implications of solar neutrino experiments.


title: Non-resonant direct p- and d-wave neutron capture by 12C

abstract:
  Discrete gamma-rays from the neutron capture state of 13C to its low-lying
bound states have been measured using pulsed neutrons at En = 550 keV. The
partial capture cross sections have been determined to be 1.7+/-0.5,
24.2+/-1.0, 2.0+/-0.4 and 1.0+/-0.4 microb for the ground (1/2-), first (1/2+),
second (3/2-) and third (5/2+) excited states, respectively. From a comparison
with theoretical predictions based on the non-resonant direct radiative capture
mechanism, we could determine the spectroscopic factor for the 1/2+ state to be
0.80 +/- 0.04, free from neutron-nucleus interaction ambiguities in the
continuum. In addition we have detected the contribution of the non-resonant
d-wave capture component in the partial cross sections for transitions leading
to the 1/2- and 3/2- states. While the s-wave capture dominates at En < 100
keV, the d-wave component turns out to be very important at higher energies.
  From the present investigation the 12C(n,gamma)13C reaction rate is obtained
for temperatures in the range 10E+7 - 10E+10 K.