title: Probing the DeltaNN component of 3He

abstract:
  The 3He(gamma,pi^+/- p) reactions were measured simultaneously over a tagged
photon energy range of 800<E_gamma<1120 MeV, well above the Delta resonance
region. An analysis was performed to kinematically isolate Delta knockout
events from conventional Delta photoproduction events, and a statistically
significant excess of pi+p events was identified, consistent with Delta++
knockout. Two methods were used to estimate the DeltaNN probability in the 3He
ground state, corresponding to the observed knockout cross section. The first
gave a lower probability limit of 1.5+/-0.6+/-0.5%; the second yielded an upper
limit of about 2.6%.


title:
Level density and gamma strength function in 162-Dy from inelastic 3-He
  scattering

abstract:
  Complementary measurements have been performed for the level density and
gamma strength function in 162-Dy using inelastic 3-He scattering. Comparing
these results to previous measurements using the 163-Dy(3-He,alpha) reaction,
reveals that the measured quantities above 1.5 MeV do not depend significantly
on the nuclear reaction chosen.


title:
Dileptons as Probes of High-Density Hadronic Matter: Results from the
  SPS Heavy-Ion Programme

abstract:
  The most recent results on dileptons obtained in the CERN heavy-ion programme
are reviewed.


title: A Study of the $\Delta^-$-component of the wave-function in light nuclei

abstract:
  We have measured cross sections for the $ (\pi^+,\pi^\pm p)$ reactions on
${\rm ^3H}$, ${\rm ^4He}$, ${\rm ^6Li}$ and ${\rm ^7Li}$ in quasi-free
kinematics at incident pion beam energy 500 MeV. An enhancement of the
$(\pi^+,\pi^- p)$ cross section in this kinematics is observed. If this is
interpreted as due to quasi-free scattering from pre-existing $\Delta$
components of the nuclear wave function, the extracted probabilities are in
agreement with theoretical expectations.


title: Meson Production Experiments with Electromagnetic Beams using CLAS

abstract:
  The CEBAF Large Acceptnace Spectrometer (CLAS) has been taking production
data since February, 1998. It takes data for many reactions simultaneously with
moderate resolution. Data has been taken for a variety of conditions with
polarized and unpolarized beam and target. Preliminary results of the initial
experiments run by the CLAS collaboration are shown. The connection with the
study of N* resonances is emphasized.


title: Measurement of p + d -> 3He + eta in S(11) Resonance

abstract:
  We have measured the reaction p + d -> 3He + eta at a proton beam energy of
980 MeV, which is 88.5 MeV above threshold using the new ``germanium wall''
detector system. A missing--mass resolution of the detector system of 2.6% was
achieved. The angular distribution of the meson is forward peaked. We found a
total cross section of (573 +- 83(stat.) +- 69(syst.))nb. The excitation
function for the present reaction is described by a Breit Wigner form with
parameters from photoproduction.


title:
Evidence of Xi hypernuclear production in the
  ^{12}C(K^-,K^+)^{12}_{Xi}Be reaction

abstract:
  The E885 collaboration utilized the 1.8 GeV/c K^- beam line at the AGS to
accumulate 3 x 10^5 (K^-,K^+) events. Xi hypernuclear states are expected to be
produced through the reaction K^- + ^{12}C -> K^+ + ^{12}_{Xi}Be. The measured
missing-mass spectrum indicates the existence of a signal below the threshold
for free Xi production. Although the resolution was not sufficient to resolve
discrete hypernuclear states, the excess of events in the region of missing
mass, kinematically inaccessible in free Xi production, is compared to
theoretical prediction for ^{12}_{Xi}Be production.


title: Measurement of Spin Correlation coefficients in \vec p \vec p --> d pi^+

abstract:
  The spin correlation coefficent combinations A_{xx}+A_{yy} and A_{xx}-A_{yy},
the spin correlation coefficients A_{xz} and A_{zz}, and the analyzing power
were measured for \vec p \vec p --> d pi^+ between center-of-mass angles 25 deg
\leq \theta \leq 65 deg at beam energies of 350.5, 375.0 and 400.0 MeV. The
experiment was carried out with a polarized internal target and a stored,
polarized beam. Non-vertical beam polarization needed for the measurement of
A_{zz} was obtained by the use of solenoidal spin rotators. Near threshold,
only a few partial waves contribute, and pion s- and p-waves dominate with a
possible small admixture of d-waves. Certain combinations of the observables
reported here are a direct measure of these d-waves. The d-wave contributions
are found to be negligible even at 400.0 MeV.


title: Probing Baryon Freeze-out Density at the AGS with Proton Correlations

abstract:
  First measurements of the beam energy dependence of the two proton
correlation function in central Au+Au collisions are performed by the E895
Collaboration at the BNL AGS. The imaging technique of Brown-Danielewicz is
used in order to extract information about the proton source at freeze-out.
Measured correlation functions and sources do not exhibit significant changes
with beam energy.


title:
Peculiarities of isotopic temperatures obtained from p+A collisions at 1
  GeV

abstract:
  Nuclear temperatures obtained from inclusive measurements of double isotopic
yield ratios of fragments produced in 1 GeV p + A collisions amount to about 4
MeV nearly independent from the target mass.


title: Near-Threshold eta Meson Production in Proton-Proton Collisions

abstract:
  The production of eta mesons has been measured in the proton-proton
interaction close to the reaction threshold using the COSY-11 internal facility
at the cooler synchrotron COSY. Total cross sections were determined for eight
different excess energies in the range from 0.5 MeV to 5.4 MeV. The energy
dependence of the total cross section is well described by the available
phase-space volume weighted by FSI factors for the proton-proton and proton-eta
pairs.


title: On the discovery of doubly-magic $^{48}$Ni

abstract:
  The paper reports on the first observation of doubly-magic Nickel-48 in an
experimental at the SISSI/LISE3 facility of GANIL. Four Nickel-48 isotopes were
identified. In addition, roughly 100 Nickel-49, 50 Iron-45, and 290 Chromium-42
isotopes were observed. This opens the possibility to search for two-proton
emission from these nuclei.


title:
Search for the $\Delta ^{++}$ component in $^{12}C$ ground state using
  $^{12}C(\gamma, \pi ^{+}p)$ reaction

abstract:
  The differential cross section for the reaction $^{12}$C$(\gamma ,\pi ^{+}p)$
has been measured in the $\Delta$ resonance region at high recoil momenta of
the residual nuclear system. The data are analysed under the assumption that
the formation of $\pi^+p$ pairs may be interpreted as
$\gamma\Delta^{++}\to\pi^+p$ process, proceeding on the $\Delta^{++}$
constituent in a target nucleus. As a result, the estimation $N_\Delta=0.028\pm
0.008$ deltas per nucleon in $^{12}$C was obtained.


title: Exploring vector meson masses in nuclear collisions

abstract:
  The formalism developed earlier by us for the propagation of a resonance in
the nuclear medium in proton-nucleus collisions has been modified to the case
of vector boson production in heavy-ion collisions. The first part of the talk
describes this formalism. The formalism includes coherently the contribution to
the observed di-lepton production from the decay of a vector boson inside as
well as outside the nuclear medium. The calculated invariant rho mass
distributions are presented for the $\rho $-meson production using optical
potentials estimated within the VDM and the resonance model.
  In the second part of the talk we write a formalism for coherent rho
production in proton nucleus collisions and explore the sensitivity of the
(p,p$^\prime \rho ^0$) reaction cross section to medium mass modification of
the rho meson.


title: Lambda-Neutron Scattering Lengths from Radiative K-minus Capture

abstract:
  Radiative capture of the K-minus by the deuteron as a reaction for
measurement of the Lambda-neutron scattering lengths. The use of spin
information to separate the singlet and triplet scattering lengths is treated.


title:
Angular momentum projected analysis of Quadrupole Collectivity in
  \protect(^{30,32,34}Mg\protect) and \protect(^{32,34,36,38}Si\protect) with
  the Gogny interaction

abstract:
  A microscopic angular momentum projection after variation is used to describe
quadrupole collectivity in (^{30,32,34}Mg) and (^{32,34,36,38}Si). The
Hartree-Fock-Bogoliubov states obtained in the quadrupole constrained mean
field approach are taken as intrinsic states for the projection. Excitation
energies of the first (2^{+}) states and the (B(E2,0^{+}\to 2^{+})) transition
probabilities are given. A reasonable agreement with available experimental
data is obtained. It is also shown that the mean field picture of those nuclei
is strongly modified by the projection.


title:
Projectile $\Delta$ and target-Roper excitation in the p (d, d')X
  reaction

abstract:
  In this paper we compare a model that contains the mechanisms of $\Delta$
excitation in the projectile and Roper excitation in the target with
experimental data from two (d, d') experiments on a proton target. The
agreement of the theory with the experiment is fair for the data taken at T_d =
2.3 GeV. The $\Delta$ excitation in the projectile is predicted close to the
observed energy with the correct width. The theory, however, underpredicts by
about 40% the cross sections measured at T_d = 1.6 GeV at angles where the
cross section has fallen by about two orders of magnitude. The analysis done
here allows to extract an approximate strength for the excitation of the Roper
[N^*(1440)] excitation and a qualitative agreement with the theoretical
predictions is also found.


title:
Realistic Ghost State : Pauli Forbidden State from Rigorous Solution of
  the Alpha Particle

abstract:
  The antisymmetrization of the composite particles in cluster model
calculations manifests itself in Pauli forbidden states (ghost states), if one
restricts oneself on undeformed cluster in the low energy region. The
resonating group method and the generating coordinate method rely on a property
of the norm kernel, which introduces some of the ghost states. The norm kernel
has been usually calculated under the assumption that the inner wavefunctions
have a simple Gaussian form. It is the first time that this assumption is
tested by the rigorous way. In the 4He+N system, we demonstrate a ghost state,
which is calculated from a rigorous solution of Yakubovsky equations for the
alpha particle. The ghost states calculated by rigorous and approximate methods
turn out to have a very similar form. It is analytically proved that the trace
of the norm kernel does not depend on the inner wavefunction we choose.


title: Triplet Pairing in Neutron Matter

abstract:
  The separation method developed earlier by us [Nucl. Phys. {\bf A598} 390
(1996)] to calculate and analyze solutions of the BCS gap equation for
$^1$S$_0$ pairing is extended and applied to $^3$P$_2$--$^3$F$_2$ pairing in
pure neutron matter. The pairing matrix elements are written as a separable
part plus a remainder that vanishes when either momentum variable is on the
Fermi surface. This decomposition effects a separation of the problem of
determining the dependence of the gap components in a spin-angle representation
on the magnitude of the momentum (described by a set of functions independent
of magnetic quantum number) from the problem of determining the dependence of
the gap on angle or magnetic projection. The former problem is solved through a
set of nonsingular, quasilinear integral equations, providing inputs for
solution of the latter problem through a coupled system of algebraic equations
for a set of numerical coefficients. An incisive criterion is given for finding
the upper critical density for closure of the triplet gap. The separation
method and its development for triplet pairing exploit the existence of a small
parameter, given by a gap-amplitude measure divided by the Fermi energy. The
revised BCS equations admit analysis revealing universal properties of the full
set of solutions for $^3$P$_2$ pairing in the absence of tensor coupling,
referring especially to the energy degeneracy and energetic order of these
solutions. The angle-average approximation introduced by Baldo et al. is
illuminated in terms of the separation-transformed BCS problem and the small
parameter expansion...


title: Two-Body Correlations in Nuclear Systems

abstract:
  Correlations in the nuclear wave-function beyond the mean-field or
Hartree-Fock approximation are very important to describe basic properties of
nuclear structure. Various approaches to account for such correlations are
described and compared to each other. This includes the hole-line expansion,
the coupled cluster or ``exponential S'' approach, the self-consistent
evaluation of Greens functions, variational approaches using correlated basis
functions and recent developments employing quantum Monte-Carlo techniques.
Details of these correlations are explored and their sensitivity to the
underlying nucleon-nucleon interaction. Special attention is paid to the
attempts to investigate these correlations in exclusive nucleon knock-out
experiments induced by electron scattering. Another important issue of nuclear
structure physics is the role of relativistic effects as contained in
phenomenological mean field models. The sensitivity of various nuclear
structure observables on these relativistic features are investigated. The
report includes the discussion of nuclear matter as well as finite nuclei.


title: Aspects of thermal and chemical equilibration of hadronic matter

abstract:
  We study thermal and chemical equilibration in 'infinite' hadron matter as
well as in finite size relativistic nucleus-nucleus collisions using a BUU
cascade transport model that contains resonance and string degrees-of-freedom.
The 'infinite' hadron matter is simulated within a cubic box with periodic
boundary conditions. The various equilibration times depend on baryon density
and energy density and are much shorter for particles consisting of light
quarks then for particles including strangeness. For kaons and antikaons the
chemical equilibration time is found to be larger than $\simeq$ 40 fm/c for all
baryon and energy densities considered. The inclusion of continuum excitations,
i.e. hadron 'strings', leads to a limiting temperature of $T_s\simeq$ 150 MeV.
We, furthermore, study the expansion of a hadronic fireball after
equilibration. The slope parameters of the particles after expansion increase
with their mass; the pions leave the fireball much faster then nucleons and
accelerate subsequently heavier hadrons by rescattering ('pion wind'). If the
system before expansion is close to the limiting temperature $T_s$, the slope
parameters for all particles after expansion practically do not depend on
(initial) energy and baryon density. Finally, the equilibration in relativistic
nucleus-nucleus collision is considered. Since the reaction time here is much
shorter than the equilibration time for strangeness, a chemical equilibrium of
strange particles in heavy-ion collisions is not supported by our transport
calculations. However, the various particle spectra can approximately be
described within the blast model.


title: Collisional Quenching of the 2S State of Muonic Hydrogen

abstract:
  We have calculated differential, total and transport cross sections for
muonic hydrogen in the n=2 state scattering from hydrogen. The metastable
fraction of the 2S state that slows down below the 2P threshold without
undergoing collisional quenching has been calculated as a function of the
initial kinetic energy using a Monte Carlo kinetics program. Contrary to
earlier estimates, the metastable fraction in the kinetic energy range of 2-5
eV cannot be neglected.


title:
Pion abundance and entropy in the hydrodynamical description of
  relativistic nuclear collisions

abstract:
  We show that a hydrodynamical model with continuous particle emission instead
of sudden freeze out can explain both the strange particle abundances and pion
abundance from NA35 without extra assumption (e.g., sequential freeze out,
modified equation of state, sudden plasma hadronization,...). In this scenario,
the observation of a larger pion abundance is natural and does not imply a
higher initial entropy and early plasma phase.


title: Equation of state of nucleonic matter

abstract:
  The nuclear equation of state (EoS) is investigated by flow phenomena in
relativistic heavy-ion collisions, both in transverse and radial direction, in
comparison to experimental data from 150 A MeV to 11 A GeV. To this aim the
collective dynamics of the nucleus-nucleus collision is described within a
transport model of the coupled channel RBUU type. There are two factors which
dominantly determine the baryon flow at these energies: the momentum dependence
of the scalar ($U_S$) and vector potentials ($U_\mu$) for baryons and the
resonance/string degrees of freedom for energetic hadron excitations. We fix
the explicit momentum dependence of the nucleon-meson couplings by the nucleon
optical potential up to 1 GeV and extrapolate to higher energy. When assuming
the optical potential to vanish identically for $E_{kin} \geq 3.5$ GeV we
simultaneously describe the sideward flow data of the PLASTIC BALL, FOPI, EoS
and E877 collaborations, the elliptic flow data of the E895 and E877
collaborations and approximately the rapidity and transverse mass distribution
of protons at AGS energies without employing any {\it explicit} assumption on a
phase transition in the EoS. However, the gradual change from hadronic to
string degrees of freedom with increasing bombarding energy can be viewed as a
transition from {\it hadronic} to {\it string} matter, i.e. a dissolution of
hadrons at high energy density.


title: The Delta I=1/2 rule in non-mesonic weak decay of Lambda-hypernuclei

abstract:
  By employing recent data on non-mesonic decay of s-shell Lambda-hypernuclei
we study, within the phenomenological model of Block and Dalitz, the validity
of the Delta I=1/2 rule in the Lambda N--> NN process. Due to the low
experimental precision, a possible violation of this rule can be neither proved
nor excluded at present with sufficient accuracy: a pure Delta I=1/2 transition
amplitude is excluded at 40% confidence level.


title:
A Calculation of Baryon Diffusion Constant in Hot and Dense Hadronic
  Matter Based on an Event Generator URASiMA

abstract:
  We evaluate thermodynamical quantities and transport coefficients of a dense
and hot hadronic matter based on an event generator URASiMA (Ultra-Relativistic
AA collision Simulator based on Multiple Scattering Algorithm). The statistical
ensembles in equilibrium with fixed temperature and chemical potential are
generated by imposing periodic boundary condition to the simulation of URASiMA,
where energy density and baryon number density is conserved. Achievement of the
thermal equilibrium and the chemical equilibrium are confirmed by the common
value of slope parameter in the energy distributions and the saturation of the
numbers of contained particles, respectively. By using the generated ensembles,
we investigate the temperature dependence and the chemical potential dependence
of the baryon diffusion constant of a dense and hot hadronic matter.


title: Vector Mesons in Medium and Dileptons in Heavy-Ion Collisions

abstract:
  Theoretical approaches to assess modifications of vector mesons in the
medium, as well as their experimental identification via electromagnetic
probes, are discussed. Implications for the nature of chiral symmetry
restoration in hot/dense matter are outlined and put into context with the
axialvector channel.


title:
Light-particle emission from the fissioning nuclei 126Ba, 188Pt and
  (266,272,278)/110: theoretical predictions and experimental results

abstract:
  We present a comparison of our model treating fission dynamics in conjunction
with light-particle (n, p, alpha) evaporation with the available experimental
data for the nuclei 126Ba, 188Pt and three isotopes of the element Z=110. The
dynamics of the symmetric fission process is described through the solution of
a classical Langevin equation for a single collective variable characterizing
the nuclear deformation along the fission path. A microscopic approach is used
to evaluate the emission rates for pre-fission light particles.
Entrance-channel effects are taken into account by generating an initial spin
distribution of the compound nucleus formed by the fusion of two deformed
nuclei with different relative orientations.


title: Strongly damped nuclear collisions: zero or first sound ?

abstract:
  The relaxation of the collective quadrupole motion in the initial stage of a
central heavy ion collision at beam energies $E_{lab}=5\div20$ AMeV is studied
within a microscopic kinetic transport model. The damping rate is shown to be a
non-monotonic function of E_{lab} for a given pair of colliding nuclei. This
fact is interpreted as a manifestation of the zero-to-first sound transition in
a finite nuclear system.


title: The neutron star in the Relativistic Mean-Field Theory

abstract:
  The nucleon effective mass, binding energy and neutron star configuration in
the Relativistic Mean-Field Theory (RMF) is considered. The calculation are
motivated by the construction of the equation of state for a neutron star in
the RMF. The equation of state for the parameters set TM1 is calculated using
the Feynman - Bogolubov variational method for temperature different from zero.
The structure of the neutron star is presented. The maximal stable
configuration are obtained for: M_max=1.91 M_Sun and R=12.84 km.


title:
Shell-model calculations of stellar weak interaction rates: II. Weak
  rates for nuclei in the mass range A=45-65 in supernovae environment

abstract:
  Based on large-scale shell model calculations we have determined the electron
capture, positron capture and beta-decay rates on more than 100 nuclei in the
mass range A=45-65. The rates are given for densities \rho Y_e =10^7-10^{10}
mol/cm^3 and temperatures T=10^9-10^{10} K and hence are relevant for both
types of supernovae (Type Ia and Type II). The shell model electron capture
rates are significantly smaller than currently assumed. For proton-to-baryon
ratios Y_e=0.42-0.46 mol/g, the beta-decay rates are faster than the electron
capture rates during the core collapse of a massive star.


title: Comment on Yuan et al

abstract:
  The work of Yuan et al. (Phys. Rev. C 60 (1999) 045203) is being represented
as definitive regarding the non-existence of a particular nonstrange,
isoscalar, spin three dibaryon which has been proposed. We comment on this
paper and its relation to our work and that of others.


title:
Description of quadrupole collectivity in N ~ 20 nuclei with techniques
  beyond the mean field

abstract:
  Properties of the ground and several collective excited states of the light
nuclei ^{30,32,34}Mg are described in the framework of the angular momentum
projected Generator Coordinate Method using the quadrupole moment as collective
coordinate and the Gogny force as the effective interaction. The calculated
excitation energies and B(E2) transition probabilities agree reasonably well
with experiment. The results clearly indicate that both the restoration of the
rotational symmetry and the quadrupole dynamics are key ingredients for the
description of the properties of the above mentioned nuclei.


title:
Further Comments On The Effects of Deformation on Isovector
  Electromagnetic and Weak Transition Strengths

abstract:
  We present a superior proof that the results for summed strength isovector
dipole, spin dipole, and orbital dipole excitations are independent of
deformations at the Delta N = 0 level.


title: Dressing the nucleon in a dispersion approach

abstract:
  We present a model for dressing the nucleon propagator and vertices. In the
model the use of a K-matrix approach (unitarity) and dispersion relations
(analyticity) are combined. The principal application of the model lies in
pion-nucleon scattering where we discuss effects of the dressing on the phase
shifts.


title:
Shell Corrections for Finite-Depth Deformed Potentials: Green's Function
  Oscillator Expansion Method

abstract:
  Shell corrections of the finite deformed Woods-Saxon potential are calculated
using the Green's function method and the generalized Strutinsky smoothing
procedure. They are compared with the results of the standard prescription
which are affected by the spurious contribution from the unphysical particle
gas. In the new method, the shell correction approaches the exact limit
provided that the dimension of the single-particle (harmonic oscillator) basis
is sufficiently large. For spherical potentials, the present method is faster
than the exact one in which the contribution from the particle continuum states
is explicitly calculated. For deformed potentials, the Green's function method
offers a practical and reliable way of calculating shell corrections for weakly
bound nuclei.


title: Excitation functions of hadronic observables from SIS to RHIC energies

abstract:
  We calculate excitation functions for various dynamical quantities as well as
experimental observables from SIS to RHIC energies within the HSD transport
approach which is based on string, quark, diquark ($q, \bar{q}, qq,
\bar{q}\bar{q}$) and hadronic degrees of freedom without including any explicit
phase transition to a quark-gluon plasma (QGP). It is argued that the failure
of this more 'conventional' approach in comparison to experimental data should
indicate the presence of a different phase which might be either attributed to
space-time regions of vanishing scalar quark condensate ($<q\bar{q}>$ = 0) or
to the presence of a QGP phase with strongly interacting partons. We study the
$K/\pi$ ratio, the low mass dilepton enhancement in the invariant mass regime
from 0.2 -- 1.2 GeV as well as charmonium suppression for central Au + Au
collisions as a function of the bombarding energy and present predictions for
these observables as well as hadron rapiditiy distributions at RHIC energies.
Whereas all observables studied within HSD show smooth increasing/decreasing
excitation functions, the experimental $K^+/\pi^+$ ratio indicates a maximum at
11 A$\cdot$GeV (or above) which is interpreted as a signature for a chirally
restored phase in the course of the reaction.


title: Solutions of the pion dispersion equation in the medium: new aspects

abstract:
  In symmetrical nuclear matter the solutions of pion dispersion equation are
investigated in the complex plane of the pion frequency \omega. There are three
well-known branches of solutions on the physical sheet : sound, pion and
isobar, at the matter density less than the critical one \rho <\rho_c. At \rho
>\rho_c the fourth branch appears on the physical sheet. For this branch the
condition \omega^2_c\leq0 (in general case Re\omega^2_c\leq0) takes place. This
points out the instability of the ground state which is possibly related to the
pion condensation.


title:
Solar Proton Burning Process Revisited within a Covariant Model Based on
  the Bethe-Salpeter Formalism

abstract:
  A covariant model based on the Bethe-Salpeter formalism is proposed for
investigating the solar proton burning process $pp\to De^+\nu_e$ and the
near-threshold deuteron disintegration via electromagnetic and weak
interactions. Results of numerical calculations of the energy dependence of
relevant cross sections and the astrophysical low-energy cross section factor
$S_{pp}$ of the proton burning process are presented. Our results confirm
previous canonical values, and the energy dependence of the $S_{pp}$ factor is
rather close to phenomenological extrapolations commonly adopted in
computations of solar nuclear reaction rates.


title: Production of \phi Mesons in Near-Threshold \pi N and N N Reactions

abstract:
  We analyze the production of $\phi$ mesons in $\pi N$ and NN reactions in the
near-threshold region, using throughout the conventional ``non-strange''
dynamics based on such processes which are allowed by the non-ideal
$\omega-\phi$ mixing. We show that the occurrence of the direct $\phi NN$
interaction may show up in different unpolarized and polarization observables
in $\pi N\to N\phi$ reactions. We find a strong non-trivial difference between
observables in the reactions $pp\to pp\phi$ and $pn\to pn\phi$ caused by the
different role of the spin singlet and triplet states in the entrance channel.
A series of predictions for the experimental study of this effect is presented.


title:
Inertial parameters and superfluid-to-normal phase transition in
  superdeformed bands

abstract:
  The quasiclassically exact solution for the second inertial parameter $\cal
B$ is found in self-consistent way. It is shown that superdeformation and
nonuniform pairing arising from the rotation induced pair density significantly
reduce this inertial parameter. The different limiting cases for $\cal B$,
which allow to study an interplay between rapid rotation, pairing correlations,
and mean field deformation, are considered. The new signature for the
transition from pairing to normal phase is suggested in terms of the variation
of ${\cal B}/{\cal A}$ versus spin. Experimental data indicate the existence of
such transition in the three superdeformed mass regions.


title:
Sensitivities of the Proton-Nucleus Elastical Scattering Observables of
  6He and 8He at Intermediate Energies

abstract:
  We investigate the use of proton-nucleus elastic scattering experiments using
secondary beams of 6He and 8He to determine the physical structure of these
nuclei. The sensitivity of these experiments to nuclear structure is examined
by using four different nuclear structure models with different spatial
features using a full-folding optical potential model. The results show that
elastic scattering at intermediate energies (<100 MeV per nucleon) is not a
good constraint to be used to determine features of structure. Therefore
researchers should look elsewhere to put constraints on the ground state wave
function of the 6He and 8He nuclei.


title: Effects of the secondary decays on the isotopic thermometers

abstract:
  The sharp microcanonical multifragmentation model from [Al. H. Raduta and Ad.
R. Raduta, Phys. Rev. C 55, 1344 (1997); Phys. Rev. C, in press] is employed
for evaluating the nuclear caloric curve predictions of nine isotopic
thermometers for three representative nuclei. Evaluations are performed for
both primary decay and asymptotic stages. Effects of the secondary decays on
the primary decay caloric curves are evidenced and discussed. In both cases a
dispersive character of the isotopic caloric curves with increasing the source
excitation energy is observed. A procedure of calibrating the isotopic
thermometers on the microcanonical predictions for both primary decay and
asymptotic stages is proposed. The resulting set of calibrating parameters for
each thermometer is independent on the source size, on its excitation energy
and, in the case of the primary decay, on the freeze-out radius assumption.


title: Spin-orbit interaction in Hartree-Fock calculations

abstract:
  The contribution of the spin-orbit interaction in Hartree-Fock calculations
for closed shell nuclei is studied. We obtain explicit expressions for the
finite range spin-orbit force. New terms with respect to the traditional
spin-orbit expressions are found. The importance of the finite-range is
analyzed. Results obtained with spin-orbit terms taken from realistic
interactions are presented. The effect of the spin-orbit isospin dependent
terms is evaluated.


title: Collective modes in asymmetric nuclei

abstract:
  The collective motion of a finite nuclear system is investigated by numerical
simulation and by linear response theory. Using a pseudo-particle simulation
technique we analyze the giant resonances with a multipole decomposition
scheme. We examine the energy and the damping of different giant collective
modes and obtain the dependence of these quantities on the proton-neutron
ratio. ...(abbreviated) Alternatively the giant collective modes in asymmetric
nuclear matter are investigated within linear response theory including the
collisional correlations via a dynamic relaxation time approximation. For a
multicomponent system we derive a coupled dispersion relation and show that two
sources of coupling appear: (i) a coupling of isoscalar and isovector modes due
to the action of different mean-fields and (ii) an explicit new coupling in
asymmetric matter due to collisional interaction. We show that the latter is
responsible for a new mode arising besides isovector and isoscalar
modes...(abbreviated) Collective motion beyond the linear regime is
demonstrated for the example of large-amplitude isoscalar giant octupole
excitations in finite nuclear systems. Depending on the initial conditions we
observe either clear octupole modes or over-damped octupole modes which decay
immediately into quadrupole ones. This dependence on initial correlations
represents a behaviour beyond linear response.


title:
Dynamics of Hot Bulk QCD Matter: from the Quark-Gluon Plasma to Hadronic
  Freeze-Out

abstract:
  We introduce a combined macroscopic/microscopic transport approach employing
relativistic hydrodynamics for the early, dense, deconfined stage of the
reaction and a microscopic non-equilibrium model for the later hadronic stage
where the equilibrium assumptions are not valid anymore. Within this approach
we study the dynamics of hot, bulk QCD matter, which is expected to be created
in ultra-relativistic heavy ion collisions at the SPS, the RHIC and the LHC.
Our approach is capable of self-consistently calculating the freeze-out of the
hadronic system, while accounting for the collective flow on the hadronization
hypersurface generated by the QGP expansion. In particular, we perform a
detailed analysis of the reaction dynamics, hadronic freeze-out, and transverse
flow.


title:
Correlation and Finite Interaction-Range Effects in High-Energy Electron
  Inclusive Scattering

abstract:
  We calculate cross sections of high energy electron inclusive scattering off
nuclear matter in a new and consistent formulation based on the Green's
function method with the Glauber approximation, which is an extension of our
previous work on the nuclear transparency in (e, e'p) reaction. The comparison
with other approaches is discussed. In this framework, we study the
finite-range effect of the nucleon-nucleon interaction in the final-state
interactions, and the effect of the nuclear short-range correlation. We propose
a zero-range approximation, which works well when correlation and finite
interaction-range effects are included. It greatly reduces the numerical work,
while maintaining a reasonable accuracy.


title:
Final state interactions in $^{4}$He(e,e$^\prime$p)$^{3}$H at large
  proton energy

abstract:
  At large proton energy, the final state interactions of the knocked out
nucleon in $\eep$ reactions off nuclear targets can be described within the
eikonal approximation, treating the spectator particles as a collection of
fixed scattering centers. We use a generalization of this approach, suitable to
take into account the possible occurrence of color transparency, to carry out
an accurate calculation of the missing momentum distribution of the process
$^{4}He(e,e^\prime p)^{3}H$. The pattern of final state interaction effect is
analyzed for different kinematical setups in the domain corresponding to $2 \le
Q^2 \le 20$ (GeV/c)$^2$.


title: F-spin as a Partial Symmetry

abstract:
  We use the empirical evidence that F-spin multiplets exist in nuclei for only
selected states as an indication that F-spin can be regarded as a partial
symmetry. We show that there is a class of non-F-scalar IBM-2 Hamiltonians with
partial F-spin symmetry, which reproduce the known systematics of collective
bands in nuclei. These Hamiltonians predict that the scissors states have good
F-spin and form F-spin multiplets, which is supported by the existing data.


title:
From bound states to resonances: analytic continuation of the wave
  function

abstract:
  Single-particle resonance parameters and wave functions in spherical and
deformed nuclei are determined through analytic continuation in the potential
strength. In this method, the analyticity of the eigenvalues and eigenfunctions
of the Schroedinger equation with respect to the coupling strength is exploited
to analytically continue the bound-state solutions into the positive-energy
region by means of Pade' approximants of the second kind. The method is here
applied to single-particle wave functions of the $^{154}Sm$ and $^{131}Eu$
nuclei. A comparison of the results with the direct solution of the
Schroedinger equation shows that the method can be confidently applied also in
coupled-channel situations requiring high numerical accuracy.


title: Chirality of nuclear rotation

abstract:
  It is shown that the rotating mean field of triaxial nuclei can break the
chiral symmetry. Two nearly degenerate $\Delta I =1 $ rotational bands
originate from the left-handed and right-handed solution.


title: Symmetry Breaking by Proton-Neutron Pairing

abstract:
  The symmetries of the $t=1$ and $t=0$ pair-fields are different. The
consequences for rotational spectra are discussed. For $t=1$, the concept of
spontaneous breaking and subsequent restoration of the isospin symmetry turns
out to be important. It permits us to describe the proton-neutron
pair-correlation within the conventional frame of pairing between like
particles. The experimental data are consistent with the presence of a $t=1$
field at low spin in $N\approx Z$ nuclei. For a substantial $t=0$ field, the
spectra of even-even and odd-odd $N\approx Z$ nuclei become similar. The
possibility of a rotationally induced $ J=1$ pair-field at high spin is
considered.


title: Debye screening and Meissner effect in a two-flavor color superconductor

abstract:
  I compute the gluon self-energy in a color superconductor with two flavors of
massless quarks, where condensation of Cooper pairs breaks SU(3)_c to SU(2)_c.
At zero temperature, there is neither Debye screening nor a Meissner effect for
the three gluons of the unbroken SU(2)_c subgroup. The remaining five gluons
attain an electric as well as a magnetic mass. For temperatures approaching the
critical temperature for the onset of color superconductivity, or for gluon
momenta much larger than the color-superconducting gap, the self-energy assumes
the form given by the standard hard-dense loop approximation. The gluon
self-energy determines the coefficient of the kinetic term in the effective
low-energy theory for the condensate fields.


title:
Dissipative dynamics of fission in the framework of asymptotic expansion
  of Fokker-Planck equation

abstract:
  The dynamics of fission has been formulated by generalising the asymptotic
expansion of the Fokker-Planck equation in terms of the strength of the
fluctuations where the diffusion coefficients depend on the stochastic
variables explicitly. The prescission neutron multiplicities and the mean
kinetic energies of the evaporated neutrons have been calculated and compared
with the respective experimental data over a wide range of excitation energy
and compound nuclear mass. The mean and variance of the total kinetic energies
of the fission fragments have been calculated and compared with the
experimental values.


title: Proton decay of high-lying states in odd nuclei

abstract:
  In the framework of the quasiparticle-phonon model, we study the
non-statistical proton decay of excited states in odd nuclei towards low-lying
collective states. Partial cross sections and branching ratios for the proton
decay of the high angular momentum states in $^{41}$Sc, $^{59}$Cu and $^{91}$Nb
%{\it excited by means of the ($^{7}$Li,$^{6}$He) reaction} are evaluated. The
calculated branching ratios predict strong direct proton decays to the
low-lying vibrational states in $^{41}$Sc and $^{91}$Nb. A general agreement
with existing experimental data is found.


title:
Shell model description of normal parity bands in odd-mass heavy
  deformed nuclei

abstract:
  The low-energy spectra and B(E2) electromagnetic transition strengths of
159Eu, 159Tb and 159Dy are described using the pseudo SU(3) model. Normal
parity bands are built as linear combinations of SU(3) states, which are the
direct product of SU(3) proton and neutron states with pseudo spin zero (for
even number of nucleons) and pseudo spin 1/2 (for odd number of nucleons). Each
of the many-particle states have a well-defined particle number and total
angular momentum. The Hamiltonian includes spherical Nilsson single-particle
energies, the quadrupole-quadrupole and pairing interactions, as well as three
rotor terms which are diagonal in the SU(3) basis. The pseudo SU(3) model is
shown to be a powerful tool to describe odd-mass heavy deformed nuclei.


title: Particle Multiplicities and Thermalization in High Energy Collisions

abstract:
  We investigate the conditions under which particle multiplicities in high
energy collisions are Boltzmann distributed, as is the case for hadron
production in e^+e^-, pp, p-pbar and heavy ion collisions. We show that the
apparent temperature governing this distribution does not necessarily imply
equilibrium (thermal or chemical) in the usual sense, as we explain. We discuss
an explicit example using tree level amplitudes for N photon production in
which a Boltzmann-like distribution is obtained without any equilibration. We
argue that the failure of statistical techniques based on free particle
ensembles may provide a signal for collective phenomena (such as large shifts
in masses and widths of resonances) related to the QCD phase transition.


title: Mechanisms for Direct Breakup Reactions

abstract:
  We review some simple mechanisms of breakup in nuclear reactions. We mention
the spectator breakup, which is described in the post-form DWBA. The relation
to other formulations is also indicated. An especially important mechanism is
Coulomb dissociation. It is a distinct advantage that the perturbation due to
the electric field of the nucleus is exactly known. Therefore firm conclusions
can be drawn from such measurements. Some new applications of Coulomb
dissociation for nuclear astrophysics are discussed.


title: Three-cluster nuclear molecules

abstract:
  A three-center phenomenological model able to explain, at least from a
qualitative point of view, the difference in the observed yield of a
particle-accompanied fission and that of binary fission was developed. It is
derived from the liquid drop model under the assumption that the aligned
configuration, with the emitted particle between the light and heavy fragment
is obtained by increasing continuously the separation distance, while the radii
of the light fragment and of the light particle are kept constant. During the
first stage of the deformation one has a two-center evolution until the neck
radius becomes equal to the radius of the emitted particle. Then the three
center starts developing by decreasing with the same amount the two tip
distances. In such a way a second minimum, typical for a cluster molecule,
appears in the deformation energy. Examples are presented for $^{240}$Pu parent
nucleus emitting $\alpha$-particles and $^{14}$C in a ternary process.


title: $\rho$ - nucleus bound states in Walecka model

abstract:
  Possible formation of $\rho$ nucleus bound state is studied in the framework
of Walecka model. The bound states are found in different nuclei ranging from
$^3He$ to $^{208}Pb$. These bound states may have a direct bearing on the
recent experiments on the photoproduction of $\rho$ meson in the nuclear
medium.


title: Dileptons and hadron spectral functions in heavy-ion collisions

abstract:
  We briefly review the dilepton experiments at BEVALAC/SIS and SPS energies
for p+p, p+A and A+A collisions as well as our present understanding of the
data within transport theoretical simulations. Since dileptons from p+A and A+A
collisions in particular probe the in-medium spectral functions of vector
mesons, a novel semiclassical off-shell transport approach is introduced on the
basis of the Kadanoff-Baym equations that describes the dynamical evolution of
broad hadron spectral functions. The implications of the off-shell dynamics --
relative to the conventional on-shell transport dynamics -- are discussed for
proton spectra, high energy $\gamma$, pion, kaon and antikaon production from
GANIL to AGS energies in comparison to experimental data.


title: Freeze-out in hydrodynamical models in relativistic heavy ion collisions

abstract:
  Freeze-out of particles across 3-dimensional space-time hypersurface with
space-like normal is discussed in a simple kinetic model. The final momentum
distribution of emitted particles shows a non-exponential transverse momentum
spectrum, which is in quantitative agreement with recently measured SPS pion
and $h^-$ spectra.


title: Microscopic theories of neutrino-^{12}C reactions

abstract:
  In view of the recent experiments on neutrino oscillations performed by the
LSND and KARMEN collaborations as well as of future experiments, we present new
theoretical results of the flux averaged $^{12}C(\nu_e,e^-)^{12}N$ and
$^{12}C(\nu_{\mu},{\mu}^-)^{12}N$ cross sections. The approaches used are
charge-exchange RPA, charge-exchange RPA among quasi-particles (QRPA) and the
Shell Model. With a large-scale shell model calculation the exclusive cross
sections are in nice agreement with the experimental values for both reactions.
The inclusive cross section for $\nu_{\mu}$ coming from the decay-in-flight of
$\pi^+$ is $15.2 \times 10^{-40} cm^2$ to be compared to the experimental value
of $12.4 \pm 0.3 \pm 1.8 \times 10^{-40} cm^2$, while the one due to $\nu_{e}$
coming from the decay-at-rest of $\mu^+$ is $16.4 \times 10^{-42} cm^2$ which
agrees within experimental error bars with the measured values. The shell model
prediction for the decay-in-flight neutrino cross section is reduced compared
to the RPA one. This is mainly due to the different kind of correlations taken
into account in the calculation of the spin modes and partially due to the
shell-model configuration basis which is not large enough, as we show using
arguments based on sum-rules.


title: Mass modification of D-meson at finite density in QCD sum rule

abstract:
  We evaluate the mass shift of isospin-averaged D-meson in the nuclear medium.
Borel-transformed QCD sum rules are used to describe an interaction between the
D-meson and a nucleon by taking into account all the lowest dimension-4
operators in the operator product expansion (OPE). We find at normal matter
density the D-meson mass shift is about 10 times (\sim 50 MeV) larger than that
of J/\psi. This originates from the fact that the dominant contribution in the
OPE for the D-meson is the nucleon matrix element of m_c\bar{q}q, where m_c is
the charm-quark mass and q denotes light quarks. We also discuss that the mass
shift of the D-meson in nuclear matter may cause the level crossings of the
charmonium states and the D\bar{D} threshold. This suggests an additional
mechanism of the J/\psi suppression in high energy heavy-ion collisions.


title:
Ordinary and radiative muon capture on the proton and the pseudoscalar
  form factor of the nucleon

abstract:
  We calculate ordinary and radiative muon capture on the proton in an
effective field theory of pions, nucleons and delta isobars, working to third
and second order in the small scale expansion respectively. Preceding
calculations in chiral effective field theories only employed pion and nucleon
degrees of freedom and were not able to reproduce the photon spectrum in the
pioneering experiment of radiative muon capture on the proton from TRIUMF. For
the past few years it has been speculated that the discrepancy between theory
and experiment might be due to Delta(1232) related effects, which are only
included via higher order contact interactions in the standard chiral approach.
In this report we demonstrate that this speculation does not hold true. We show
that contrary to expectations from naive dimensional analysis isobar effects on
the photon spectrum and the total rate in radiative muon capture are of the
order of a few percent, consistent with earlier findings in a more
phenomenological approach. We further demonstrate that both ordinary and
radiative muon capture constitute systems with a very well behaved chiral
expansion, both in standard chiral perturbation theory and in the small scale
expansion, and present some new ideas that might be at the bottom of the still
unresolved discrepancy between theory and experiment in radiative muon capture.
Finally we comment upon the procedure employed by the TRIUMF group to extract
new information from their radiative muon capture experiment on the
pseudoscalar form factor of the nucleon. We show that it is inconsistent with
the ordinary muon capture data.


title: Effects of Dense Matter on Hadron Production in Heavy-Ion Collisions

abstract:
  The intrinsic transverse momentum distribution of partons in the nucleon can
be used to explain a large amount of high-$p_T$ hadron and photon production
data in high-energy nucleon-nucleon collisions at energies $\sqrt{s} \approx
20$ to 1800 GeV. However, proton-nucleus experiments at energies $\approx 30$
GeV show an extra enhancement (Cronin effect) in the yield of photons and
mesons compared to a simple extrapolation of the proton-proton data. This
enhancement is due to the effect of the dense hadronic matter encountered by
the projectile proton in the nuclear environment. We discuss the origin and the
properties of the nuclear enhancement.


title:
Cranked Relativistic Hartree-Bogoliubov Theory: Formalism and
  Application to the Superdeformed Bands in the $A\sim 190$ region

abstract:
  Cranked Relativistic Hartree-Bogoliubov theory without and with approximate
particle number projection by means of the Lipkin-Nogami method is presented in
detail as an extension of Relativistic Mean Field theory with pairing
correlations to the rotating frame. Pairing correlations are taken into account
by a finite range two-body force of Gogny type. The applicability of this
theory to the description of rotating nuclei is studied in detail on the
example of superdeformed bands in even-even nuclei of the $A\sim 190$ mass
region. Different aspects such as the importance of pairing and particle number
projection, the dependence of the results on the parametrization of the RMF
Lagrangian and Gogny force etc. are investigated in detail. It is shown that
without any adjustment of new parameters the best description of experimental
data is obtained by using the well established parameter sets NL1 for the
Lagrangian and D1S for the pairing force. Contrary to previous studies at spin
zero it is found that the increase of the strength of the Gogny force is not
necessary in the framework of Relativistic Hartree-Bogoliubov theory provided
that particle number projection is performed.


title: Hadrons in Dense Resonance-Matter: A Chiral SU(3) Approach

abstract:
  A nonlinear chiral SU(3) approach including the spin 3/2 decuplet is
developed to describe dense matter. The coupling constants of the baryon
resonances to the scalar mesons are determined from the decuplet vacuum masses
and SU(3) symmetry relations. Different methods of mass generation show
significant differences in the properties of the spin-3/2 particles and in the
nuclear equation of state.


title:
Adiabatic Selfconsistent Collective Coordinate Method for Large
  Amplitude Collective Motion in Superconducting Nuclei

abstract:
  An adiabatic approximation to the selfconsistent collective coordinate method
is formulated in order to describe large amplitude collective motions in
superconducting nuclei on the basis of the time-dependent
Hartree-Fock-Bogoliubov equations of motion. The basic equations are presented
in a local harmonic form which can be solved in a similar way as the
quasiparticle RPA equations. The formalism guarantees the conservation of
nucleon number expectation values. An extension to the multi-dimensional case
is also discussed.


title: The reaction $^2H(\gamma,\pi^0)np$ in the threshold region

abstract:
  Neutral pion photoproduction on the deuteron in the inelastic channel is
studied in the threshold region from 142 to 160 MeV. The calculation is based
on the use of the diagrammatic approach. Contributions from the pole diagrams,
one-loop diagrams both with $n$-$p$ and $\pi$-$N$ rescattering as well as
two-loop diagrams with simultaneous inclusion of these rescattering mechanisms
are taken into account. We have found a reasonable agreement with a very simple
calculation by J.C. Bergstrom et al. [Phys. Rev. C 57 (1998) 3203]. It is shown
that the `effective' electric dipole deuteron amplitude $E_d$ is negative in
agreement with a prediction of ChPT. We conclude that a deviation of about 20%
from a ChPT prediction for $E_d$ discovered in an experiment on coherent
$\pi^0$ photoproduction off the deuteron cannot be attributed to inadequate
estimates of inelastic channel contributions. We suggest that $\pi$-$N$
rescattering is responsible for the deviation of the free-nucleon $p_1$
threshold amplitude from the value measured in that experiment


title: Electroproduction of the d* dibaryon

abstract:
  The unpolarized cross section for the electroproduction of the isoscalar
$J^\pi = 3^+$ di-delta dibaryon $d^*$ is calculated for deuteron target using a
simple picture of elastic electron-baryon scattering from the $\Delta \Delta
(^7D_1)$ and the $NN (^3S_1)$ components of the deuteron. The calculated
differential cross section at the electron lab energy of 1 GeV has the value of
about 0.24 (0.05) nb/sr at the lab angle of 10$^\circ$ (30$^\circ$) for the
Bonn B potential when the dibaryon mass is taken to be 2.1 GeV. The cross
section decreases rapidly with increasing dibaryon mass. A large calculated
width of 40 MeV for $d^*(\Delta\Delta ^7S_3)$ combined with a small
experimental upper bound of 0.08 MeV for the $d^*$ decay width appears to have
excluded any low-mass $d^*$ model containing a significant admixture of the
$\Delta\Delta (^7S_3)$ configuration.


title: alpha-nucleus potentials for the neutron-deficient p nuclei

abstract:
  alpha-nucleus potentials are one important ingredient for the understanding
of the nucleosynthesis of heavy neutron-deficient p nuclei in the astrophysical
gamma-process where these p nuclei are produced by a series of (gamma,n),
(gamma,p), and (gamma,alpha) reactions. I present an improved alpha-nucleus
potential at the astrophysically relevant sub-Coulomb energies which is derived
from the analysis of alpha decay data and from a previously established
systematic behavior of double-folding potentials.


title: Deeply bound levels in kaonic atoms

abstract:
  Using a microscopic antikaon-nucleus optical potential recently developed by
Ramos and Oset (nucl-th/9906016, in print in Nuclear Physics A) from a chiral
model, we calculate strong interaction shifts and widths for $K^-$ atoms. This
purely theoretical potential gives an acceptable description of the measured
data ($\chi^2/{\rm num.data}= 3.8$), though it turns out to be less attractive
than what can be inferred from the existing kaon atomic data. We also use a
modified potential, obtained by adding to the latter theoretical one a s-wave
term which is fitted to known experimental kaonic data ($\chi^2/{\rm degree of
freedom}= 1.6$), to predict deeply bound $K^-$ atomic levels, not detected yet.
This improved potential predicts, in general, states even narrower than those
recently reported by Friedman and Gal. (Phys.Let.B459, 1999, 43). This
reinforces the idea that these deeply atomic states can be detected and
resolved by using suitable nuclear reactions. Besides, we also study $K^-$ and
$\bar K^0$ nuclear bound states and compute binding energies and widths, for
both species of antikaons, in $^{12}$C, $^{40}$Ca and $^{208}$Pb. Despite of
restricting our study only to potentials obtained from best fits to the known
kaonic atom data, the dynamics of these nuclear bound states depend
dramatically on the particular optical potential used.


title:
Generator Coordinate Method Calculations for Ground and First Excited
  Collective States in $^{4}$He, $^{16}$O and $^{40}$Ca Nuclei

abstract:
  The main characteristics of the ground and, in particular, the first excited
monopole state in the $^{4}$He, $^{16}$O and $^{40}$Ca nuclei are studied
within the generator coordinate method using Skyrme-type effective forces and
three construction potentials, namely the harmonic-oscillator, the square-well
and Woods-Saxon potentials. Calculations of density distributions, radii,
nucleon momentum distributions, natural orbitals, occupation numbers and
depletions of the Fermi sea, as well as of pair density and momentum
distributions are carried out. A comparison of these quantities for both ground
and first excited monopole states with the available empirical data and with
the results of other theoretical methods are given and discussed in detail.


title: Meson Particle-Hole Dynamics

abstract:
  Particle-hole modes with quantum numbers of pions and negative kaons can
propagate in nuclear matter. We discuss possible manifestations of these modes
in experiments on heavy-ion collisions and on neutrino-nucleus scattering.
Calculations of reaction rates in medium can be harmed by double counting,
which arises because the very same quantum numbers can be carried in medium as
by single particle excitations as by multi-particle ones. We argue that the
optical theorem written in terms of the non-equilibrium Green's functions
provides a convenient formalism (closed diagram technique) void of double
counting.


title: Soft Modes, Quantum Transport and Kinetic Entropy

abstract:
  The effects of the propagation of particles which have a finite life-time and
an according width in their mass spectrum are discussed in the context of
transport descriptions. In the first part the coupling of soft photon modes to
a source of charged particles is studied in a classical model which can be
solved completely in analytical terms. The solution corresponds to a
re-summation of certain field theory diagrams. The general properties of broad
resonances in dense finite temperature systems are discussed at the example of
the $\rho$-meson in hadronic matter. The second part addresses the problem of
transport descriptions which also account for the damping width of the
particles. The Kadanoff--Baym equation after gradient approximation together
with the $\Phi$-derivable method of Baym provides a self-consistent and
conserving scheme. Memory effects appearing in collision term diagrams of
higher order are discussed. We derive a generalized expression for the
nonequilibrium kinetic entropy flow, which includes corrections from
fluctuations and mass-width effects. In special cases an $H$-theorem is proved.
Memory effects in collision terms provide contributions to the kinetic entropy
flow that in the Fermi-liquid case recover the famous bosonic type $T^3 \ln T$
correction to the specific heat of liquid Helium-3.


title: T-dependence of pseudoscalar and scalar correlations

abstract:
  Inhomogeneous pseudoscalar and scalar Bethe-Salpeter equations solved using a
renormalisation-group-improved rainbow-ladder truncation exhibit bound state
poles below and above T_c, the critical temperature for chiral symmetry
restoration. Above T_c the bound state amplitudes are identical, as are the
positions and residues of the pseudoscalar and scalar poles in the vertices. In
the chiral limit the pi^0 -> gamma gamma coupling vanishes at T_c, as do f_pi,
m_sigma, g_{sigma pi pi}. For light current-quark masses the 2-pi decay channel
of the isoscalar-scalar meson remains open until very near T_c, and the widths
of the dominant pion decay modes remain significant in the vicinity of the
crossover.


title: Nuclear Saturation with QCD sum rules

abstract:
  The scalar and vectorial self energies obtained through QCD sum rules are
introduced in the Quantum Hadrodynamics (QHD) equations. This QHD and QCD
mixing show us that the effect of the density on the coupling constants is very
small.


title:
Pion Interferometry From A Relativistic Fluid With A First Order Phase
  Transition In CERN-SPS 158 GeV/A Pb+Pb Collisions

abstract:
  We investigate pion source sizes through the Yano-Koonin-Podgoretski\u{\i}
(YKP) parametrization for the Hanbury-Brown Twiss (HBT) effect in the CERN-SPS
158 GeV/A central collisions. We calculate two-particle correlation functions
numerically based on a (3+1)-dimensional relativistic hydrodynamics with a
first order phase transition and analyze the pair momentum dependence of the
HBT radii extracted from the YKP parametrization in detail. We find that even
in the case of a first order phase transition, expansion and the surface
dominant freeze-out make the source in the hydrodynamical model opaque
significantly. Consequently, the interpretation of the temporal radius
parameter as the time duration becomes unavailable for the hydrodynamical
model.


title:
QCD sum rules for J/psi in the nuclear medium: calculation of the Wilson
  coefficients of gluon operators up to dimension 6

abstract:
  We calculate the Wilson coefficients of all dimension 6 gluon operators with
non zero spin in the correlation function between two heavy vector currents.
For the twist-4 part, we first identify the three independent gluon operators,
and then proceed with the calculation of the Wilson coefficients using the
fixed point gauge. Together with the previous calculation of the Wilson
coefficients for the dimension 6 scalar gluon operators by Nikolaev and
Radyushkin, our result completes the list of all the Wilson coefficients of
dimension 6 gluon operators in the correlation function between heavy vector
currents. We apply our results to investigate the mass of $J/\psi$ in nuclear
matter using QCD sum rules. Using an upper bound estimate on the matrix
elements of the dimension 6 gluon operators to linear order in density, we find
that the density dependent contribution from dimension 6 operators is less than
40% of the dimension 4 operators with opposite sign. The final result gives
about -4 MeV mass shift for the charmonium at rest in nuclear matter.


title: A Model for the 3He(\vec d, p)4He Reaction at Intermediate Energies

abstract:
  Polarization correlation coefficients have been measured atRIKEN for the \vec
3He(\vec d,p)4He reaction at intermediate energies. We propose a model for the
(\vec d, p) reaction mechanism using the pd elastic scattering amplitude which
is rigorously determined by a Faddeev calculation and using modern NN forces.
Our theoretical predictions for deuteron polarization observables A_y, A_{yy},
A_{xx} and A_{xz} at E_d=140, 200 and 270 MeV agree qualitatively in shape with
the experimental data for the reaction 3He(\vec d,p)4He.


title: Temperature, chemical potential and the rho meson

abstract:
  We describe some applications of the Dyson-Schwinger equations at
nonzero-(T,mu). Employing a simple model dressed-gluon propagator we determine
the boundary of the deconfinement phase transition and the medium dependence of
rho-meson properties. We introduce an extension to describe the time-evolution
of scalar and vector self energies.


title: Quark Coulomb Interactions and the Mass Difference of Mirror Nuclei

abstract:
  We study the Okamoto-Nolen-Schiffer (ONS) anomaly in the binding energy of
mirror nuclei at high density by adding a single neutron or proton to a quark
gluon plasma. In this high-density limit we find an anomaly equal to two-thirds
of the Coulomb exchange energy of a proton. This effect is dominated by quark
electromagnetic interactions---rather than by the up-down quark mass
difference. At normal density we calculate the Coulomb energy of neutron matter
using a string-flip quark model. We find a nonzero Coulomb energy because of
the neutron's charged constituents. This effect could make a significant
contribution to the ONS anomaly.


title: Faddeev approach to confined three-quark problems

abstract:
  We propose a method that allows for the efficient solution of the three-body
Faddeev equations in the presence of infinitely rising confinement
interactions. Such a method is useful in calculations of nonrelativistic and
especially semirelativistic constituent quark models. The convergence of the
partial wave series is accelerated and possible spurious contributions in the
Faddeev components are avoided. We demonstrate how the method works with the
example of the Goldstone-boson-exchange chiral quark model for baryons.


title:
Interrelation between the isoscalar octupole phonon and the
  proton-neutron mixed-symmetry quadrupole phonon in near spherical nuclei

abstract:
  The interrelation between the octupole phonon and the low-lying
proton-neutron mixed-symmetry quadrupole phonon in near-spherical nuclei is
investigated. The one-phonon states decay by collective E3 and E2 transitions
to the ground state and by relatively strong E1 and M1 transitions to the
isoscalar 2+ state. We apply the proton-neutron version of the Interacting
Boson Model including quadrupole and octupole bosons (sdf-IBM-2). Two F-spin
symmetric dynamical symmetry limits of the model, namely the vibrational and
the \gamma-unstable ones, are considered. We derive analytical formulae for
excitation energies as well as B(E1), B(M1), B(E2) and B(E3) values for a
number of transitions between low-lying states.


title: The Quasi-Molecular Stage of Ternary Fission

abstract:
  We developed a three-center phenomenological model,able to explain
qualitatively the recently obtained experimental results concerning the
quasimolecular stage of a light-particle accompanied fission process. It was
derived from the liquid drop model under the assumption that the aligned
configuration, with the emitted particle between the light and heavy fragment,
is reached by increasing continuously the separation distance, while the radii
of the heavy fragment and of the light particle are kept constant. In such a
way,a new minimum of a short-lived molecular state appears in the deformation
energy at a separation distance very close to the touching point. This minimum
allows the existence of a short-lived quasi-molecular state, decaying into the
three final fragments.The influence of the shell effects is discussed. The
half-lives of some quasimolecular states which could be formed in the $^{10}$Be
and $^{12}$C accompanied fission of $^{252}$Cf are roughly estimated to be the
order of 1 ns, and 1 ms, respectively.


title: S=I=0 Pion Pairs in the A(pi,pi pi)X Reaction

abstract:
  Recent experimental results show a large enhancement of the 2 pion emission
on the scalar isoscalar channel, which had been predicted by some theoretical
estimates. We present here a detailed calculation of the A(pi, 2pi)X process
incorporating a microscopic model for the elementary reaction in vacuum,
pion-pion final state interaction in the nuclear medium, and other nuclear
medium effects.


title: The $F/D$ ratio and meson-baryon couplings from QCD sum rules-II

abstract:
  Using QCD sum rules, we compute the diagonal meson-baryon couplings, $\pi
NN$, $\eta NN$, $\pi \Xi\Xi$, $\eta \Xi\Xi$, $\pi \Sigma \Sigma$ and $\eta
\Sigma \Sigma$, from the baryon-baryon correlation function with a meson,
$i\int d^4x e^{iq\cdot x} < 0| T J_B(x) {\bar J}_B(0)|M(p)>$. The calculations
are performed to leading order in $p_\mu$ by considering the two separate Dirac
structures, $i \gamma_5 \gamma_\mu p^\mu$ and $\gamma_5 \sigma_{\mu \nu} {q^\mu
p^\nu}$ separately. We first improve the previous sum rule calculations on
these Dirac structures for the $\pi NN$ coupling by including three-particle
pion wave functions of twist 4 and then extend the formalism to calculate the
other couplings, $\eta NN$, $\pi \Xi\Xi$, $\eta \Xi\Xi$, $\pi \Sigma \Sigma$
and $\eta \Sigma \Sigma$. In the SU(3) symmetric limit, we identify the terms
responsible for the $F/D$ ratio in the OPE by matching the obtained couplings
with their SU(3) relations. Depending on the Dirac structure considered, we
find different identifications for the $F/D$ ratio. The couplings including the
SU(3) breaking effects are also discussed within our approach.


title: Proton recoil polarization in exclusive (e,e'pp) reactions

abstract:
  The general formalism of nucleon recoil polarization in the (${\vec
e},e'{\vec N}N$) reaction is given. Numerical predictions are presented for the
components of the outgoing proton polarization and of the polarization transfer
coefficient in the specific case of the exclusive $^{16}$O(${\vec e},e'{\vec
p}p$)$^{14}$C knockout reaction leading to discrete states in the residual
nucleus. Reaction calculations are performed in a direct knockout framework
where final-state interactions and one-body and two-body currents are included.
The two-nucleon overlap integrals are obtained from a calculation of the
two-proton spectral function of $^{16}$O where long-range and short-range
correlations are consistently included. The comparison of results obtained in
different kinematics confirms that resolution of different final states in the
$^{16}$O(${\vec e},e'{\vec p}p$)$^{14}$C reaction may act as a filter to
disentangle and separately investigate the reaction processes due to
short-range correlations and two-body currents and indicates that measurements
of the components of the outgoing proton polarization may offer good
opportunities to study short-range correlations.


title:
Transport Theoretical Approach to the Nucleon Spectral Function in
  Nuclear Matter

abstract:
  The nucleon spectral function in infinite nuclear matter is calculated in a
quantum transport theoretical approach. Exploiting the known relation between
collision rates and correlation functions the spectral function is derived
self-consistently. By re-inserting the spectral functions into the collision
integrals the description of hard processes from the high-momentum components
of wave functions and interactions is improved iteratively until convergence is
achieved. The momentum and energy distributions and the nuclear matter
occupation probabilities are in very good agreement with the results obtained
from many-body theory.


title: Magnetic instability of quark matter

abstract:
  Spontaneous magnetization of quark liquid is examined. It is pointed out that
quark liquid has potential to be ferromagnetic at rather low densities.


title: A phenomenological analysis of antiproton interactions at low energies

abstract:
  We present an optical potential analysis of the antiproton-proton
interactions at low energies. Our optical potential is purely phenomenological,
and has been parametrized on data recently obtained by the Obelix Collaboration
at momenta below 180 MeV/c. It reasonably fits annihilation and elastic data
below 600 MeV/c, and allows us for an evaluation of the elastic cross section
and rho-parameter down to zero kinetic energy. Moreover we show that the
mechanism that depresses antiproton-nucleus annihilation cross sections at low
energies is present in antiproton-proton interactions too.


title: Ground states of the Wick-Cutkosky model using light-front dynamics

abstract:
  We consider the ground state in a model with scalar nucleons and a meson
using the formalism of light-front dynamics. Light-front potentials for
two-nucleon bound states are calculated using two approaches. First,
light-front time-ordered perturbation theory is used to calculate one- and
two-meson-exchange potentials. These potentials give results that agree well
with the ladder and ladder plus crossed box Bethe-Salpeter spectra. Secondly,
approximations that incorporate non-perturbative physics are used to calculate
alternative one-meson-exchange potentials. These non-perturbative potentials
give better agreement with the spectra of the full non-perturbative
ground-state calculation than the perturbative potentials. For lightly-bound
states, all of the approaches appear to agree with each other.


title:
Shell Effects in Nuclei with Vector Self-Coupling of Omega Meson in
  Relativistic Hartree-Bogoliubov Theory

abstract:
  Shell effects in nuclei about the stability line are investigated within the
framework of the Relativistic Hartree-Bogoliubov (RHB) theory with
self-consistent finite-range pairing. Using 2-neutron separation energies of Ni
and Sn isotopes, the role of $\sigma$- and $\omega$-meson couplings on the
shell effects in nuclei is examined. It is observed that the existing
successful nuclear forces (Lagrangian parameter sets) based upon the nonlinear
scalar coupling of $\sigma$-meson exhibit shell effects which are stronger than
suggested by the experimental data. We have introduced nonlinear vector
self-coupling of $\omega$-meson in the RHB theory. It is shown that the
inclusion of the vector self-coupling of $\omega$-meson in addition to the
nonlinear scalar coupling of $\sigma$-meson provides a good agreement with the
experimental data on shell effects in nuclei about the stability line. A
comparison of the shell effects in the RHB theory is made with the Hartree-Fock
Bogoliubov approach using the Skyrme force SkP. It is shown that the
oft-discussed shell quenching with SkP is not consistent with the available
experimental data.


title: The $\eta NN$ coupling constant

abstract:
  We derive the light cone QCD sum rule for the $\eta NN$ coupling constant
$g_{\eta NN} $. The contribution from the excited states and the continuum is
subtracted cleanly through the double Borel transform with respect to the two
external momenta, $p_1^2$, $p_2^2=(p-q)^2$. Our result is $\alpha_{\eta
NN}=(0.3\pm 0.15)$, which favors small values used in literatures.


title: Toward Chiral Theory of NN interactions in nuclear matter

abstract:
  The effective chiral theory of the in-medium NN interactions is considered.
  The shallow bound states, which complicate the effective field theory
analysis in vacuum do not exist in matter. We show that the next-to-leading
order terms in the chiral expansion of the effective Lagrangian can be
interpreted as corrections so that the expansion is systematic. The Low Energy
Effective Constants of this Lagrangian are found to satisfy the concept of
naturalness. The potential energy per particle is calculated. The problems and
challenges in constructing the chiral theory of nuclear matter are outlined.


title: Hadronic in-Medium Effects with Elementary Probes

abstract:
  The sensitivity of dilepton production in elementary reactions of photons and
pions with nuclei on in-medium changes of hadronic properties is studied. It is
shown that this sensitivity is comparable to that encountered in
ultrarelativistic heavy-ion collisions. It is also shown how a significant
broadening of the mesons affects other photonuclear processes.


title: Realistic Shell-Model Calculations for Proton-Rich N=50 Isotones

abstract:
  The structure of the N=50 isotones 98Cd, 97Ag, and 96Pd is studied in terms
of shell model employing a realistic effective interaction derived from the
Bonn-A nucleon-nucleon potential. The single-hole energies are fixed by
resorting to an analysis of the low-energy spectra of the isotones with A>= 91.
Comparison shows that our results are in very satisfactory agreement with the
available experimental data. This supports confidence in the predictions of our
calculations


title: Quantum Monte Carlo calculations of A=8 nuclei

abstract:
  We report quantum Monte Carlo calculations of ground and low-lying excited
states for A=8 nuclei using a realistic Hamiltonian containing the Argonne v18
two-nucleon and Urbana IX three-nucleon potentials. The calculations begin with
correlated eight-body wave functions that have a filled alpha-like core and
four p-shell nucleons LS-coupled to the appropriate (J+/-;T) quantum numbers
for the state of interest. After optimization, these variational wave functions
are used as input to a Green's function Monte Carlo calculation made with a new
constrained path algorithm. We find that the Hamiltonian produces an 8Be ground
state that is within 2 MeV of the experimental resonance, but the other
eight-body energies are progressively worse as the neutron-proton asymmetry
increases. The 8Li ground state is stable against breakup into subclusters, but
the 8He ground state is not. The excited state spectra are in fair agreement
with experiment, with both the single-particle behavior of 8He and 8Li and the
collective rotational behavior of 8Be being reproduced. We also examine energy
differences in the T=1 and 2 isomultiplets and isospin-mixing matrix elements
in the excited states of 8Be. Finally, we present densities, momentum
distributions, and studies of the intrinsic shapes of these nuclei, with 8Be
exhibiting a definite 2-alpha cluster structure.


title: Matter induced $\rho$-$\delta$ mixing : a source of dileptons

abstract:
  We study the possibility of $\rho-\delta$ mixing via N-N excitations in dense
nuclear matter. This mixing induces a peak in the dilepton spectra at an
invariant mass equal to that of the $\delta$. We calculate the cross section
for dilepton production through the mixing process and we compare its size with
that of $\pi-\pi$ annihilation. In-medium masses and mixing angles are also
calculated.


title: Finite T meson correlations and quark deconfinement

abstract:
  Finite temperature spatial $\bar q q$ correlation modes in the $\pi$ and
$\rho$ channels are studied with the rainbow-ladder truncated quark
Dyson-Schwinger equation and Bethe-Salpeter equation in the Matsubara
formalism. To retain the finite range of the effective interaction while
facilitating summation over fermion Matsubara modes necessary to ensure
continuity at {T=0}, a separable kernel is used. The model is fixed by {T=0}
properties and it implements dynamical chiral symmetry breaking and quark
confinement. Above and below the deconfinement and chiral restoration
transitions, we study $M_\pi(T)$, $f_\pi(T)$ and the 3-space transverse and
longitudinal masses $M_\rho^T(T)$ and $M_\rho^L(T)$. For the $\rho$ mode we
also study the strong and electromagnetic partial widths to determine the
$T$-dependence that is generated by the quark content. The $\rho \to \pi \pi$
width decreases sharply just above the chiral restoration transition leaving
the $\rho$ with only its narrow {$e^+ e^-$} width. We discuss improvements
needed by this model, especially in regard to the high $T$ behavior of the
masses where we compare to lattice QCD simulations.


title: Polarization phenomena in the reaction NN to NNpi near threshold

abstract:
  First calculations for spin-dependent observables of the reactions $pp \to
pp\pi^0$, $pp \to pn\pi^+$ and $pp \to d\pi^+$ near threshold are presented,
employing the J\"ulich model for pion production. The influence of resonant
(via the excitation of the $\Delta (1232)$) and non-resonant p-wave pion
production mechanisms on these observables is examined. For the reactions $pp
\to pn\pi^+$ and $pp \to d\pi^+$ nice agreement of our predictions with the
presently available data on spin correlation coefficents is observed whereas
for $pp \to pp\pi^0$ the description of the data is less satisfying.


title: Quark Substructure and Isobar Effects on Deuteron Form-Factors

abstract:
  Elastic ed scattering, with deuteron polarization, up to high momentum
transfer provides detailed information on the deuteron wave function. This
determines the range dependence of the orbital and spin components of the one-
and two-body currents, restricting contributions of isobar and meson-exchange
currents and of quark/gluon degrees of freedom, as well as the nucleon
component. The R-matrix boundary condition model combines all these effects,
predicting nucleon-nucleon reactions and the deuteron form-factors
simultaneously. A brief description of the model is followed by a comparison of
its results with data, emphasizing the restrictions placed on the model by ed
elastic form-factors.


title: Complete one-loop analysis of the nucleon's spin polarizabilities

abstract:
  We present a complete one-loop analysis of the four nucleon spin
polarizabilities in the framework of heavy baryon chiral perturbation theory.
The first non-vanishing contributions to the isovector and first corrections to
the isoscalar spin polarizabilities are calculated. No unknown parameters enter
these predictions. We compare our results to various dispersive analyses. We
also discuss the convergence of the chiral expansion and the role of the delta
isobar.


title:
Inclusive meson production in peripheral collisions of ultrarelativistic
  heavy ions

abstract:
  There exist several proposals to use Weizs\"{a}cker-Williams photons
generated by ultrarelativistic heavy ions to produce exotic particles in
$\gamma\gamma$ fusion reactions. To estimate the background conditions for such
reactions we analyze various mechanisms of meson production in very peripheral
collisions of ultrarelativistic heavy ions at RHIC and LHC energies. Besides
$\gamma\gamma$ fusion they include also electromagnetic $\gamma A$ interactions
and strong nucleon-nucleon interactions in grazing $AA$ collisions. All these
processes are characterised by low multiplicities of produced particles.
$\gamma A$ and $AA$ events are simulated by corresponding Monte Carlo codes,
RELDIS and FRITIOF. In each of these processes a certain fraction of pions is
produced close to the mid-rapidity region that gives a background for the
$\gamma\gamma$ events. The possibility of selecting mesons produced in
$\gamma\gamma$ fusion events via different $p_t$ cut procedures is
demonstrated.


title: Modeling J/psi Properties at Finite Temperature

abstract:
  We model J/psi using an effective lagrangian approach and calculate its
spectral function in a gas of light mesons at finite temperature. We explore
the hadronic landscape estimating cross sections for elastic and inelastic
channels. Effects of form factors are tested in a general, but consistently
gauge invariant manner. Relevance to heavy ion experiments is discussed.


title: Parton picture of inclusive quasi-elastic electron scattering off nuclei

abstract:
  A parton picture of inclusive quasi-elastic electron-nucleus scattering,
where individual nucleons are treated as (non point-like) partons of the
nucleus, is presented. All the necessary target-mass corrections to asymptotic
scaling are evaluated and a new scaling variable is obtained. Recent inclusive
data from Jefferson Lab are analyzed and shown to scale in terms of the new
variable. The new approach allows to extract in a model-independent way the
nucleon light-cone momentum distribution in the nucleus.


title: Dropping Sigma-Meson Mass and In-Medium Pion-Pion Correlations

abstract:
  The influence of a dropping sigma-meson mass on previously calculated
in-medium pion-pion correlations in the J=I=0 (sigma-meson) channel is
investigated. It is found that the invariant-mass distribution around the
vacuum threshold experiences a further strong enhancement over and above the
standard many-body effects. The relevance of this result for the theoretical
interpretation of this result for the theoretical interpretation of recent
A(pi-2 pi)X data is pointed out.


title: In-medium Pion-Pion Interaction and Chiral Symmetry Restoration

abstract:
  We discuss medium modifications of the unitarized pion-pion interaction in
the nuclear medium. We incorporate both the effects of chiral symmetry
restoration and the influence of collective nuclear pionic modes, originating
from the p-wave coupling of the pion to delta-hole configurations. We show how
the resulting strong enhancement of the sigma-meson spectral function is
related to large fluctuations of the condensate associated with the partial
restoration of chiral symmetry.


title:
Phenomenological local potentials for \pi^- + ^{12}C scattering from 120
  to 766 MeV

abstract:
  Pion-nucleus scattering cross sections are calculated by solving a
Schr\"{o}dinger equation reduced from the Klein-Gordon equation. Local
potentials are assumed, and phenomenological potential parameters are searched
energy-dependently for $\pi^{-} + ^{12}$C system so as to reproduce not only
elastic differential cross sections but also total elastic, reaction and total
cross sections at 13 pion incident energies from 120 to 766 MeV. The real and
imaginary parts of the local potentials thus obtained are shown to satisfy the
dispersion relation. The imaginary part of the potentials as a function of the
pion energy is found to peak near the $\Delta$(1232)-resonance energy. The
strong absorption radius of the pion projectile with incident energies near the
$\Delta$-resonance region is found to be about $1.6 A^{1/3}$ fm, which is
consistent with previous studies of the region where the decay of the
$\Delta$'s takes place in nuclei. The phenomenological local potentials are
then compared with the local potentials exactly phase-shift equivalent to
Kisslinger potentials for pion energies near the $\Delta$-resonance.


title:
Cross Sections for the Dissociation of J/psi and psi' by pi and rho at
  low energies

abstract:
  Using the quark-interchange model of Barnes and Swanson, we evaluate the
dissociation cross sections for $J/\psi$ and $\psi'$ by $\pi$ and $\rho$ at low
collision energies. In collisions with $\pi$ mesons near threshold the $\pi +
J/\psi$ dissociation cross section is predicted to be small, but the $\pi
+\psi'$ cross section is found to be quite large, in qualitative agreement with
experimental data on $J/\psi$ and $\psi'$ production in high-energy heavy-ion
collisions. The $\rho + J/\psi$ and $\rho + \psi'$ dissociation cross sections
are both predicted to be large numerically and are divergent near threshold.
These $\rho + J/\psi$ and $\rho + \psi'$ cross sections show considerable
sensitivity to the mass of the $\rho$ meson if it is off energy shell.


title:
Coupled $\Lambda N-\Sigma N$ and $\Lambda NN-\Sigma NN$ systems and
  hyperon-nucleon interactions

abstract:
  This paper summarizes our studies of the hypertriton and describes our
findings on the hyperon-nucleon interaction, especially on the role of the
$\Lambda N-\Sigma N$ coupling and the strengths of the $S$-wave $YN$
interactions. We briefly comment on our ongoing analyses with electromagnetic
probes.


title: Phenomenological aspects of kaon photoproduction on the nucleon

abstract:
  Using an isobar model which can reproduce the existing experimental data of
kaon photoproduction on the nucleon we investigate some related
phenomenological aspects, i.e. the hadronic form factors, contributions of
kaon-hyperon final states to the anomalous magnetic moment of the nucleon, and
missing nucleon resonances. By reggeizing the appropriate propagators we extend
the model to the higher photon energy regime.


title: Hyperon polarization in kaon photoproduction from the deuteron

abstract:
  We analyze the reaction gamma + d --> K^+ + Lambda (Sigma) + N using the
Nijmegen soft core hyperon-nucleon interactions NSC97f and NSC89 and a recently
updated production operator for the gamma + N --> K^+ + Lambda(Sigma)
processes. Significant effects of the YN final state interaction are found near
both the K^+ Lambda N and K^+ Sigma N thresholds.


title: Partial dynamical symmetry in a fermion system

abstract:
  The relevance of the partial dynamical symmetry concept for an interacting
fermion system is demonstrated. Hamiltonians with partial SU(3) symmetry are
presented in the framework of the symplectic shell-model of nuclei and shown to
be closely related to the quadrupole-quadrupole interaction. Implications are
discussed for the deformed light nucleus $^{20}$Ne.


title:
Extracting particle freeze-out phase-space densities and entropies from
  sources imaged in heavy-ion reactions

abstract:
  The space-averaged phase-space density and entropy per particle are both
fundamental observables which can be extracted from the two-particle
correlation functions measured in heavy-ion collisions. Two techniques have
been proposed to extract the densities from correlation data: either by using
the radius parameters from Gaussian fits to meson correlations or by using
source imaging, which may be applied to any like pair correlation. We show that
the imaging and Gaussian fits give the same result in the case of meson
interferometry. We discuss the concept of an equivalent instantaneous source on
which both techniques rely. We also discuss the phase-space occupancy and
entropy per particle. Finally, we propose an improved formula for the
phase-space occupancy that has a more controlled dependence on the uncertainty
of the experimentally measured source functions.


title: Dileptons from transport and hydrodynamical models

abstract:
  Transport and hydrodynamical models used to describe the expansion stage of a
heavy-ion collision at the CERN SPS give different dilepton spectrum even if
they are tuned to reproduce the observed hadron spectra. To understand the
origin of this difference we compare the dilepton emission from transport and
hydrodynamical models using similar initial states in both models. We find that
the requirement of pion number conservation in a hydrodynamical model does not
change the dilepton emission. Also the mass distribution from the transport
model indicates faster cooling and longer lifetime of the fireball.


title: Quantum Monte Carlo calculations of six-quark states

abstract:
  The variational Monte Carlo method is used to find the ground state of six
quarks confined to a cavity of diameter R_c, interacting via an assumed
non-relativistic constituent quark model (CQM) Hamiltonian. We use a flux-tube
model augmented with one-gluon and one-pion exchange interactions, which has
been successful in describing single hadron spectra. The variational wave
function is written as a product of three-quark nucleon states with
correlations between quarks in different nucleons. We study the role of quark
exchange effects by allowing flux-tube configuration mixing. An accurate
six-body variational wave function is obtained. It has only ~13% rms
fluctuation in the total energy and yields a standard deviation of ~<.1%; small
enough to be useful in discerning nuclear interaction effects from the large
rest mass of the two nucleons. Results are presented for three values of the
cavity diameter, R_c=2, 4, and 6 fm. They indicate that the flux-tube model
Hamiltonian with gluon and pion exchange requires revisions in order to obtain
agreement with the energies estimated from realistic two-nucleon interactions.
We calculate the two-quark probability distribution functions and show how they
may be used to study and adjust the model Hamiltonian.


title:
Evidence for a New State of Matter: An Assessment of the Results from
  the CERN Lead Beam Programme

abstract:
  This "position paper" collects the scientific arguments behind the CERN Press
Release of February 10, 2000, which announced evidence for the creation of a
new state of matter in Pb-Pb collisions at the CERN SPS. The data on which this
paper is based were presented in a special seminar at CERN on the same day, a
recording of which can be accessed at
http://www.cern.ch/CERN/Announcements/2000/NewStateMatter/ .


title:
A hybrid version of the tilted axis cranking model and its application
  to ^{128}Ba

abstract:
  A hybrid version the deformed nuclear potential is suggested, which combines
a spherical Woods Saxon potential with a deformed Nilsson potential. It removes
the problems of the conventional Nilsson potential in the mass 130 region.
Based on the hybrid potential, tilted axis cranking calculations are carried
out for the magnetic dipole band in ^{128}Ba.


title: Dilepton Production and Chiral Symmetry

abstract:
  We discuss how dilepton production is related to chiral symmetry and its
restoration. We then analyse presently available data by the CERES
collaboration in this context. We find that the present data do not support any
conclusions concerning the restoration of chiral symmetry. We finally provide a
prediction for the dilepton spectrum for the just completed low energy (40 GeV)
run at the SPS.


title:
Microscopic study of energy and centrality dependence of transverse
  collective flow in heavy-ion collisions

abstract:
  The centrality dependence of directed and elliptic flow in light and heavy
systems of colliding nuclei is studied within two microscopic transport models
at energies from 1 AGeV to 160 A GeV. The pion directed flow has negative slope
in the midrapidity range irrespective of bombarding energy and mass number of
the colliding ions. In contrast, the directed flow of nucleons vanishes and
even develops antiflow in the midrapidity range in (semi)peripheral collisions
at energies around 11.6 A GeV and higher. The origin of the disappearance of
flow is linked to nuclear shadowing. Since the effect is stronger for a light
system, it can be distinguished from the similar phenomenon caused by the
quark-gluon plasma formation. In the latter case the disappearance of the flow
due to the softening of the equation of state should be most pronounced in
collisions of heavy ions. The centrality dependence of the elliptic flow shows
that the maximum in the <v_2(b)> distribution is shifted to very peripheral
events with rising incident energy, in accord with experimental data. This is
an indication of the transition from baryonic to mesonic degrees of freedom in
hot hadronic matter.


title: Superheavy Nuclei in a Chiral Hadronic Model

abstract:
  Superheavy nuclei are investigated in a nonlinear chiral SU(3)-model. The
proton number Z=120 and neutron numbers of N=172, 184 and 198 are predicted to
be magic. The charge distributions and alpha-decay chains hint towards a hollow
structure.


title:
Roles of quark-pair correlations in baryon structure and non-leptonic
  weak transitions of hyperon

abstract:
  Roles of quark-pair correlations in the baryon structure and the hyperon
non-leptonic weak decay are studied within the non-relativistic constituent
quark model. We construct the SU(3) ground state baryons by solving the three
body problem rigorously with the confinement force and the short range
spin-dependent attraction. We emphasize the importance of the $s=0$ quark-quark
correlation to reproduce the $\Delta I=1/2$ enhancement of the hyperon decay,
and demonstrate that resulting static properties as well as the decay
amplitudes agree with the experiments, if we deal with the $s=0$ correlation
properly. Special attention is also put on the consequences of the SU(6)
spin-flavor symmetry breaking due to the $s=0$ correlation. Calculated magnetic
moments are the almost same as the naive SU(6) predictions in spite of the
existence of the strong correlations.


title:
Giant monopole resonance and nuclear compression modulus for 40Ca and
  16O

abstract:
  Using a collective potential derived on the basis of the Generator Coordinate
Method with Skyrme interactions we obtain values for the compression modulus of
40Ca which are in good agreement with a recently obtained experimental value.
Calculated values for the compression modulus for 16O are also given. The
procedure involved in the derivation of the collective potential is briefly
reviewed and discussed.


title: The BCS theory of q-deformed nucleon pairs - qBCS

abstract:
  We construct a coherent state of q-deformed zero coupled nucleon pairs
distributed in several single-particle orbits. Using a variational approach,
the set of equations of qBCS theory, to be solved self consistently for
occupation probabilities, gap parameter Delta, and the chemical potential
lambda, is obtained. Results for valence nucleons in nuclear degenerate sdg
major shell show that the strongly coupled zero angular momentum nucleon pairs
can be substituted by weakly coupled q-deformed zero angular momentum nucleon
pairs. A study of Sn isotopes reveals a well defined universe of (G, q) values,
for which qBCS converges. While the qBCS and BCS show similar results for Gap
parameter Delta in Sn isotopes, the ground state energies are lower in qBCS.
The pairing correlations in N nucleon system, increase with increasing q (for q
real).


title:
Violation of pseudospin symmetry in nucleon-nucleus scattering: exact
  relations

abstract:
  An exact determination of the size of the pseudospin symmetry violating part
of the nucleon-nucleus scattering amplitude from scattering observables is
presented. The approximation recently used by Ginocchio turns out to
underestimate the violation of pseudospin symmetry. Nevertheless the conclusion
of a modestly broken pseudospin symmetry in proton-208Pb scattering at
EL=800MeV remains valid.


title:
Transition from hadronic to partonic interactions for a composite
  spin-1/2 model of a nucleon

abstract:
  A simple model of a composite nucleon is developed in which a fermion and a
boson, representing quark and diquark constituents of the nucleon, form a bound
state owing to a contact interaction. Photon and pion couplings to the quark
provide vertex functions for the photon and pion interactions with the
composite nucleon. By a suitable choice of cutoff parameters of the model,
realistic electromagnetic form factors are obtained. When a pseudoscalar
pion-quark coupling is used, the pion-nucleon coupling is predominantly
pseudovector. A virtual photopion amplitude is considered in which there are
two types of contributions: hadronic contributions where the photon and pion
interactions have an intervening propagator of the nucleon or its excited
states, and contact-like contributions where the photon and pion interactions
occur within a single vertex. At large Q, the contact-like contributions are
dominant. The model nucleon exhibits scaling behavior in deep-inelastic
scattering and the normalization of the parton distribution provides a rough
normalization of the contact-like contributions. Calculations for the virtual
photopion amplitude are performed using kinematics appropriate to its
occurrence as a meson-exchange current in electron-deuteron scattering. The
results show that the contact-like terms can dominate the meson-exchange
current for Q > 1 GeV/c. There is a direct connection of the contact-like terms
to the off-forward parton distributions of the model nucleon.


title: Nucleon-nucleon interaction: Central potential and pion production

abstract:
  We show that the tail of the chiral two-pion exchange nucleon-nucleon
potential is proportional to the $\pi N$ scalar form factor and discuss how it
can be translated into effective scalar meson interactions. We then construct a
kernel for the process $NN\to\pi NN$, due to the exchange of two pions, which
may be used in either three body forces or pion production in NN scattering.
Our final expression involves a partial cancellation among three terms, due to
chiral symmetry, but the net result is still important. We also find that, at
large internucleon distances, the kernel has the same spatial dependence as the
central NN potential and we produce expressions relating these processes
directly.