title: Nuclear Fusion via Triple Collisions in Solar Plasma

abstract:
  We consider several nuclear fusion reactions that take place at the center of
the sun, which are omitted in the standard pp-chain model. More specifically
the reaction rates of the nonradiative production of ^3He, ^7Be, and ^8B nuclei
in triple collisions involving electrons are estimated within the framework of
the adiabatic approximation. These rates are compared with those of the
corresponding binary fusion reactions.


title: The dispersion relation of pion in nuclear matter

abstract:
  We put forward a formalism to calculate the relativistic particle - hole and
delta - hole excitation polarization insertion for pion propagator by using the
particle - hole - antiparticle representation of nucleon and delta propagators
in nuclear matter. The real and the imaginary part of the polarization
insertion and the dispersion relation for pion propagator are calculated
numerically. We find that the short range correlation enhances the delta - hole
excitation but suppresses the particle - hole excitation, it also suppresses
the pion condensation. We find that the effect of the short range correlation
on the pion dispersion relation depends very much on the form of the short
range correlation and the parameters involved.


title: Reduction of the spin-orbit potential in light drip-line nuclei

abstract:
  The isospin dependence of the spin-orbit interaction in light neutron rich
nuclei is investigated in the framework of relativistic mean field theory. The
magnitude of the spin-orbit potential is considerably reduced in drip line
nuclei, resulting in smaller energy splittings between spin-orbit partners. The
effect does not depend on the parametrization of the effective Lagrangian. The
results are compared with corresponding calculations in the non-relativistic
Skyrme model.


title: Selectivity of the 16O(e,e'pp) reaction to discrete final states

abstract:
  Resolution of discrete final states in the $^{16}$O(e,e$'$pp)$^{14}$C
reaction may provide an interesting tool to discriminate between contributions
from one- and two-body currents in this reaction. This is based on the
observation that the $0^+$ ground state and first $2^+$ state of $^{14}$C are
reached predominantly by the removal of a $^1S_0$ pair from $^{16}$O in this
reaction, whereas other states mostly arise by the removal of a $^3P$ pair.
This theoretical prediction has been supported recently by an analysis of the
pair momentum distribution of the experimental data. In this paper we present
results of reaction calculations performed in a direct knock-out framework
where final-state interaction and one- 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 and include both long-range and short-range
correlations. The kinematics chosen in the calculations is relevant for recent
experiments at NIKHEF and Mainz.


title:
Precision Low-Energy Measurements at DA$\Phi$NE and Their Impact on
  $\bar{K}N$ Physics

abstract:
  We delineate a ``theoretical'' $\chi^2$--functional technique to implement
fixed--$t$ analyticity on the invariant amplitudes for the $\bar{K}N$,
$\pi\Lambda$, $\pi\Sigma$ coupled channels in a fast and straightforward way.


title: $\pi Y$ Phenomenology from $\bar KN$ Scattering

abstract:
  The dispersive determination of $\pi{Y}\Sigma$ coupling constants ($Y =
\Lambda, \Sigma$) and the implications for low-energy $\bar{K}N$ analysis are
discussed. (Presented by G. Violini at the "7th Int. Symp. on Meson-Nucleon
Physics and the Structure of the Nucleon, MENU '97", Vancouver, B.C., July 28th
- August 1st, 1977).


title:
Kaon Production in Heavy-Ion Collisions and Kaon Condensation in Neutron
  Stars

abstract:
  The recent past witnesses the growing interdependence between the physics of
hadrons, the physics of relativistic heavy-ion collisions, and the physics of
compact objects in astrophysics. A notable example is the kaon which plays
special roles in all the three fields. In this talk, we first review the
various theoretical investigations of kaon properties in nuclear medium. We
then present a detailed transport model study of kaon production and flow in
heavy-ion collisions at SIS energies. Finally, We discuss the effects of the
kaon in-medium properties extracted from heavy-ion data on neutron star
properties, especially on the lowering of maximum mass of neutron stars with
the onset of kaon condensation around $3\rho_0$.


title: Transverse Energy Evolution as a Test of Parton Cascade Models

abstract:
  We propose a test of Monte Carlo Parton Cascade models based on analytic
solutions of covariant kinetic theory for longitudinally boost and transverse
translation invariant boundary conditions. We compute the evolution of the
transverse energy per unit rapidity for typical mini-jet initial conditions
expected in ultra-relativistic nuclear collisions. The kinetic theory solutions
under these conditions test the models severely because they deviate strongly
from free-streaming and also from ideal Euler and dissipative Navier-Stokes
hydrodynamical approximations. We show that the newly formulated ZPC model
passes this test. In addition, we show that the initial mini-jet density would
need to be approximately four times higher than estimated with the HIJING
generator in central Au+Au collisions at c.m. energies 200 AGeV in order that
parton cascade dynamics can be approximated by Navier-Stokes hydrodynamics.


title:
Deuteron Disintegration by Protons in Kinematics of Quasi-Elastic
  Backward pd-Scattering

abstract:
  The deuteron break-up exclusive reaction $p+d \to N(180^{\circ}) +
(NN)(0^{\circ})$ is considered in the framework of the one-nucleon-exchange
mechanism at the incident proton kinetic energy 0.2--2 GeV and the relative
energy of nucleons in the forward going final NN-pair $E_{NN}=0$--20 MeV, that
is close to the kinematical conditions of the planned experiment at COSY. The
off-energy-shell effects resulting, in particular, in the node of the
half-off-shell $^1S_0$-state partial NN-scattering amplitude and the role of
higher partial waves in the subprocess $pN\to pN$ are analysed and found to be
very important, especially for the reaction $p+d \to n(180^{\circ}) +
(pp)(0^{\circ})$.
  The accuracy of some approximate relations between the cross sections of
elastic $pd$-scattering and deuteron break-up is examined in the framework of
the mechanism in question.


title:
Relativistic Hartree-Bogoliubov theory with finite range pairing forces
  in coordinate space: Neutron halo in light nuclei

abstract:
  The Relativistic Hartree Bogoliubov (RHB) model is applied in the
self-consistent mean-field approximation to the description of the neutron halo
in the mass region above the s-d shell. Pairing correlations and the coupling
to particle continuum states are described by finite range two-body forces.
Finite element methods are used in the coordinate space discretization of the
coupled system of Dirac-Hartree-Bogoliubov integro-differential eigenvalue
equations, and Klein-Gordon equations for the meson fields. Calculations are
performed for the isotopic chains of Ne and C nuclei. We find evidence for the
occurrence of neutron halo in heavier Ne isotopes. The properties of the 1f-2p
orbitals near the Fermi level and the neutron pairing interaction play a
crucial role in the formation of the halo. Our calculations display no evidence
for the neutron halo phenomenon in C isotopes.


title:
Nuclear matter with a Bose condensate of dibaryons in relativistic
  Hartree approximation

abstract:
  The Green's functions are constructed and a one-loop calculation is given for
the scalar and vector densities and for the equation of state of nuclear matter
with a Bose condensate of dibaryons. This is the lowest approximation in the
loop expansion of quantum hadrodynamics, sufficient to account for the presence
of dibaryons not in the condensate in the heterophase nucleon-dibaryon matter.
It leads to a finite effective nucleon mass and remains consistent with
increasing the density.


title: Polarization Response Functions in Kaon Electroproduction

abstract:
  The electroproduction of kaons on the nucleon is shown to be an ideal tool to
extract electromagnetic form factors of strange mesons and hyperons.
Longitudinal n(e,e'K0)Lambda cross sections are found to be sensitive to the K0
form factor, while sensitivity to the Lambda magnetic form factor can be seen
in recoil-beam double polarization observables. The KK*\gamma transition form
factor could be extracted by measuring transverse response functions in the
K-Sigma channels.


title: Dibaryons in nuclear matter

abstract:
  The possibility for occurrence of a Bose condensate of dibaryons in nuclear
matter is investigated within the framework of the Walecka model in the
mean-field approximation. Constraints for the omega - and sigma - meson
coupling constants with dibaryons following from the requirement of stability
of dibaryon matter against compression are derived and the effect of sigma -
and pi - meson exchange current contributions to the sigma - dibaryon coupling
constant is discussed. The mean-field solutions of the model are constructed.
The effective nucleon mass vanishes when the density of dibaryons approaches a
critical value about 0.15/fm^3. The Green's functions of the equilibrium binary
mixture of nucleons and dibaryons are constructed by solving the Gorkov-Dyson
system of equations in the no-loop approximation. We find that when the square
of the sound velocity is positive, the dispersion laws for all elementary
excitations of the system are real functions. This indicates stability of the
ground state of the heterophase nucleon-dibaryon mixture. In the model
considered, production of dibaryons becomes energetically favorable at higher
densities as compared to estimates based on a model of non-interacting nucleons
and dibaryons.


title: The MIT bag model in nuclear medium from EQMC and QHD descriptions

abstract:
  Recent developments in the density dependence of the MIT bag radius and
parameters in nuclear matter are discussed. Starting from the MIT bag
lagrangian density, the calculations are specialized for symmetric homogeneous
isotropic nuclear matter. A simultaneous description of the density dependence
of MIT bag model is derived from the Quantum Hadrodynamics and an extended
Quark Meson Coupling model. Results are in agreement with those derived from
Scaling Model.


title:
Hypernucleus formation and strangeness production in proton-nucleus
  reactions

abstract:
  We study the production of $\Lambda$ hyperons in $p + A$ reactions on the
basis of a BUU transport approach from 1.1 to 1.9 GeV and evaluate the
properties of the hypernuclei produced in particular with respect to their
momentum distribution in the laboratory frame. Due to elastic $\Lambda N$
scattering large cross sections for the production of heavy hypernuclei in the
order of 100 - 400 $\mu b$ are predicted for p + U at 1.5 - 1.9 GeV laboratory
energy. Whereas the $K^+ Y$ production channels are expected to be only
slightly modified in the nuclear medium, the antikaon production should be
enhanced substantially due to large attractive $K^-$ selfenergies in dense
matter. We predict an enhancement of the inclusive $K^-$ yield in p +
$^{208}$Pb collisions of a factor of $\approx$ 10 at 2 GeV laboratory energy.


title:
Pion Excess, Nuclear Correlations, and the Interpretation of ($\vec p,
  \vec n$) Spin Transfer Experiments

abstract:
  Conventional theories of nuclear interactions predict a net increase in the
distribution of virtual pions in nuclei relative to free nucleons. Analysis of
data from several nuclear experiments has led to claims of evidence against
such a pion excess. These conclusions are usually based on a collective theory
(RPA) of the pions, which may be inadequate. The issue is the energy dependence
of the nuclear response, which differs for theories with strong NN correlations
from the RPA predictions. In the present paper, information about the energy
dependence is extracted from sum rules, which are calculated for such a
correlated, noncollective nuclear theory. The results lead to much reduced
sensitivity of nuclear reactions to the correlations that are responsible for
the pion excess. The primary example is $(\vec p,\vec n)$ spin transfer, for
which the expected effects are found to be smaller than the experimental
uncertainties. The analysis has consequences for Deep Inelastic Scattering
(DIS) experiments as well.


title:
An application of the 3-dimensional q-deformed harmonic oscillator to
  the nuclear shell model

abstract:
  An analysis of the construction of a q-deformed version of the 3-dimensional
harmonic oscillator, which is based on the application of q-deformed algebras,
is presented. The results together with their applicability to the shell model
are compared with the predictions of the modified harmonic oscillator.


title: Pi-mesonic decay of the hypertriton

abstract:
  The pi-mesonic decay of the hypertriton is calculated based on a hypertriton
wavefunction and 3N scattering states, which are rigorous solutions of 3-body
Faddeev equations using realistic NN and hyperon-nucleon interactions. The
total pi-mesonic decay rate is found to be 92% of the free Lambda decay rate,
which is close to the experimental data. Together with the nonmesonic decay the
total life time of 3Lambda H is predicted to be 2.78 x 10^-10 sec which is 6 %
larger than for the free Lambda particle. The differential decay rate is
evaluated as a function of the pion momentum. The decay into the N+d+pi channel
is stronger than in the 3N+pi channel in contrast to the situation for the
nonmesonic decay. The ratio for the decay rate into 3He + pi^- to the decay
rate into all channels including pi^- is found to be 0.40, which is close to
the experimental value. We visualise the decay into the dominant channel
p+d+pi^- in a Dalitz plot. Finally we compare the polarisation of the outgoing
proton in free unpolarised Lambda-decay to the polarisation of 3He in
unpolarised 3_Lambda H-decay and we compare the closely related asymmetry of
pi^- emitted parallel and antiparallel with respect to the spin-direction for a
polarised Lambda to the corresponding asymmetry for a polarised 3_Lambda H.


title: A particle-number-conserving solution to the generalized pairing problem

abstract:
  An exact, number-conserving solution to the generalized, orbit-dependent
pairing problem is derived by introducing an infinite-dimensional algebra. A
method for obtaining eigenvalues and eigenvectors of the corresponding
Hamiltonian is also given. The relevance of the orbit-dependent pairing
solution is demonstrated by comparing predictions of the model with shell-model
calculations.


title: Dynamic Approach to Fusion of Massive Nuclei

abstract:
  The role of the entrance channel in the fusion-fission reactions leading to
nearly the same superheavy compound nucleus is studied in the framework of
dynamic model. The calculations are done for $^{48}$Ca + $^{244}$Pu and
$^{74,76}$Ge + $^{208}$Pb reactions which could lead to formation of superheavy
element Z=114. It is shown that for these reactions there is an energy window
for the values of the bombarding energy at which a capture probability is
sufficiently large. Together with the restriction coming from the intrinsic
barrier for fusion, it helps to find an optimal value of the bombarding energy
for a given projectile-target combination.


title: A unitary correlation operator method

abstract:
  The short range repulsion between nucleons is treated by a unitary
correlation operator which shifts the nucleons away from each other whenever
their uncorrelated positions are within the replusive core. By formulating the
correlation as a transformation of the relative distance between particle
pairs, general analytic expressions for the correlated wave functions and
correlated operators are given. The decomposition of correlated operators into
irreducible n-body operators is discussed. The one- and two-body-irreducible
parts are worked out explicitly and the contribution of three-body correlations
is estimated to check convergence. Ground state energies of nuclei up to mass
number A=48 are calculated with a spin-isospin-dependent potential and single
Slater determinants as uncorrelated states. They show that the deduced energy-
and mass-number-independent correlated two-body Hamiltonian reproduces all
"exact" many-body calculations surprisingly well.


title:
Minimal Relativity and $^3S_1$-$^3D_1$ Pairing in Symmetric Nuclear
  Matter

abstract:
  We present solutions of the coupled, non-relativistic $^3S_1$-$^3D_1$ gap
equations for neutron-proton pairing in symmetric nuclear matter, and estimate
relativistic effects by solving the same gap equations modified according to
minimal relativity and using single-particle energies from a
Dirac-Brueckner-Hartree-Fock calculation. As a main result we find that
relativistic effects decrease the value of the gap at the saturation density
$k_F=1.36 fm^{-1}$ considerably, in conformity with the lack of evidence for
strong neutron-proton pairing in finite nuclei.


title: Quark and gluon condensates in the quark-meson coupling model

abstract:
  Using the quark-meson coupling (QMC) model, we study the density dependence
of the quark and gluon condensates in nuclear matter. We show that the change
of the quark condensate is mainly driven by the scalar field in the medium and
that the reduction of the quark condensate is suppressed at high density, even
in the mean-field approximation. The gluon condensate decreases by 4 - 6 % at
nuclear saturation density. We also give a simple relationship between the
change of the quark condensate and that of a hadron mass in the medium.


title: Pion-Nucleon Physics and the Polarizabilities of the Nucleon

abstract:
  I discuss recent results regarding the influence of pion-nucleon and and
nucleon-resonance physics on the (spin-) polarizabilities of the nucleon as
measured in (polarized) Compton scattering.


title: Renormalization of the one-body off-diagonal Coulomb field in nuclei

abstract:
  Isospin violation effects in nuclei are investigated within a microscopic
approach which takes into account the influence of the residual strong
interaction on the Coulomb interaction. The renormalization of the off-diagonal
Coulomb field acting within a nucleus, by the residual strong interaction is
calculated analytically in a simplified RPA. From the expression for the
suppression coefficient of the isospin violating part of the Coulomb field, the
isospin violating spreading widths of isobaric analog states are derived. The
resulting reduction of the width is in agreement with the data on the isospin
symmetry restoration and with some earlier evaluations of the isospin violating
spreading widths.


title:
Warm nuclei: The transition from independent particle motion to
  collisional dominance

abstract:
  We study large scale collective dynamics of isoscalar type and examine the
influence of interactions residual to independent particle motion. It is argued
that for excitations which commonly are present in experimental situations such
interactions must not be neglected. They even help to justify better the
assumption of locality, both in time as well as in phase space, which is
necessary not only for such classic approaches to collective motion as the
"cranking model" but also for the more general picture of a transport process.
With respect to dissipation, our results are contrasted with those of wall
friction.


title:
An explanation of the ABC enhancement in the dd -> alpha X reaction at
  intermediate energies

abstract:
  The dd -> alpha X reaction is studied in a model where each pair of nucleons
in the projectile and target deuterons undergoes pion production through the NN
-> d pi reaction. The condition that the two deuterons fuse to form an
alpha-particle then leads to peaks at small missing masses, the well-known ABC
enhancement, but also a broad structure around the maximum missing mass. With a
simplified input amplitude the model gives a quantitative description of both
the alpha-particle momentum and angular distributions for a deuteron beam
energy of 1250 MeV.


title: Strangeness Enhancement and System Size in the Hadronic Gas Model

abstract:
  Strange particle enhancement in relativistic ion collisions is discussed with
particular attention to the dependence on the size of the volume and/or the
baryon number of the system.


title:
Relativistic mean-field description of light $\Lambda$ hypernuclei with
  large neutron excess

abstract:
  The Relativistic Hartree Bogoliubov model in coordinate space, with finite
range pairing interaction, is applied to the description of
$\Lambda$-hypernuclei with a large neutron excess. The addition of the
$\Lambda$ hyperon to Ne isotopes with neutron halo can shift the neutron drip
by stabilizing an otherwise unbound core nucleus. The additional binding of the
halo neutrons to the core originates from the increase in magnitude of the
spin-orbit term. Although the $\Lambda$ produces only a fractional change in
the central mean-field potential, through a purely relativistic effect it
increases the spin-orbit term which binds the outermost neutrons.


title:
Relativistic transport theory of N, \Delta and N^{*}(1440) interacting
  through $\sigma$, $\omega$ and $\pi$ mesons

abstract:
  A self-consistent relativistic integral-differential equation of the
Boltzmann-Uehling-Uhlenbeck-type for the $N^{*}$(1440) resonance is developed
based on an effective Lagrangian of baryons interacting through mesons. The
closed time-path Green's function technique and semi-classical, quasi-particle
and Born approximations are employed in the derivation. The non-equilibrium
RBUU-type equation for the $N^{*}$(1440) is consistent with that of nucleon's
and delta's which we derived before. Thus, we obtain a set of coupled equations
for the $N$, $\Delta$ and $N^{*}$(1440) distribution functions.
  All the $N^{*}$(1440)-relevant in-medium two-body scattering cross sections
within the $N$, $\Delta$ and $N^{*}$(1440) system are derived from the same
effective Lagrangian in addition to the mean field and presented analytically,
which can be directly used in the study of relativistic heavy-ion collisions.
The theoretical prediction of the free $pp \to pp^{*}(1440)$ cross section is
in good agreement with the experimental data. We calculate the in-medium $N + N
\to N + N^{*}$, $N^{*} + N \to N + N$ and $N^{*} + N \to N^{*} + N$ cross
sections in cold nuclear matter up to twice the nuclear matter density. The
influence of different choices of the $N^{*}N^{*}$ coupling strengths, which
can not be obtained through fitting certain experimental data, are discussed.
The results show that the density dependence of predicted in-medium cross
sections are sensitive to the $N^{*}N^{*}$ coupling strengths used. An evident
density dependence will appear when a large scalar coupling strength of
$g_{N^{*}N^{*}}^{\sigma}$ is assumed.


title: Meson retardation in deuteron photodisintegration above pi-threshold

abstract:
  Photodisintegration of the deuteron above pi-threshold is studied in a
coupled channel approach including N Delta- and pi d-channels with pion
retardation in potentials and exchange currents. A much improved description of
total and differential cross sections in the energy region between pi-threshold
and 400-450 MeV is achieved.


title: Optimized delta expansion for relativistic nuclear models

abstract:
  The optimized $\delta$-expansion is a nonperturbative approach for field
theoretic models which combines the techniques of perturbation theory and the
variational principle. This technique is discussed in the $\lambda \phi^4$
model and then implemented in the Walecka model for the equation of state of
nuclear matter. The results obtained with the $\delta$ expansion are compared
with those obtained with the traditional mean field, relativistic Hartree and
Hartree-Fock approximations.


title: Gauge-invariant theory of pion photoproduction with dressed hadrons

abstract:
  Based on an effective field theory of hadrons in which quantum chromodynamics
is assumed to provide the necessary bare cutoff functions, a gauge-invariant
theory of pion photoproduction with fully dressed nucleons is described. The
formalism provides consistent dynamical descriptions of pi-N --> pi-N
scattering and Gamma-N --> pi-N production mechanisms in terms of nonlinear
integral equations for fully dressed hadrons. The dressed hadron currents and
the pion photoproduction current satisfy gauge invariance in a self-consistent
manner. Approximations are discussed that make the nonlinear formalism
manageable in practice and yet preserve gauge invariance.


title: Landau Ginzburg Theory and Nuclear Matter at Finite Temperature

abstract:
  Based on recent studies of the temperature dependence of the energy and
specific heat of liquid nuclear matter, a phase transition is suggested at a
temperature $\sim .8$ MeV. We apply Landau Ginzburg theory to this transition
and determine the behaviour of the energy and specific heat close to the
critical temperature in the condensed phase.


title: Variational treatment of quenched QED using the worldline technique

abstract:
  There has been growing interest in studying the behaviour of QED in its
strong coupling limit. The reason for this is not only that it serves as a
simple prototype gauge theory for testing nonperturbative calculational
techniques which one then goes on to apply to QCD, but also because the theory
exhibits interesting behaviour in its own right. In particular, it now appears
to be quite well established that QED breaks chiral symmetry dynamically as
long as the coupling is sufficiently large. In this contribution we describe
the progress made in applying the polaron variational approach to quenched QED
within the context of the worldline formulation of field theory. Although it is
too early for quantitative results, qualitatively the approach seems promising:
The method is formulated covariantly in Minkowski space-time, the
Ward-Takahashi identities are satisfied, the connection between the bare- and
pole-masses of the electron is gauge independent, the known exact result for
the infrared dependence of the on-shell renormalized propagator is reproduced
and corrections to the variational approximation can be calculated
systematically.


title:
Strange Mesonic Transition Form Factor in the Chiral Constituent Quark
  Model

abstract:
  The form factor $g_{\rho \pi}^{(S)}(Q^{2})$ of the strange vector current
transition matrix element $<\rho| \bar{s}\gamma_\mus|\pi>$ is calculated within
the chiral quark model. A strange vector current of the constituent $U$- and
D-quarks is induced by kaon radiative corrections and this mechanism yields the
nonvanishing values of $g_{\rho\pi}^{(S)}(0)$. The numerical result at the
photon point is consistent with the one given by the $\phi $-meson dominance
model, but the fall-off in the $Q^{2}$-dependence is faster than the monopole
form factor. Mesonic radiative corrections are also examined for the
electromagnetic $\rho $-to-$\pi $ and $K^{*}$-to-$K$ transition amplitudes.


title: The interaction between H-dibaryons

abstract:
  We investigate the interaction between H-dibaryons employing a quark cluster
model with a one-gluon-exchange potential and an effective meson exchange
potential (EMEP). A deeply-bound state of two H-dibaryons due to the medium
range attraction of the EMEP is obtained. The bound H--H system has a size of
about 0.8 $\sim$ 0.9 fm because of the short-range repulsion generated by the
color-magnetic interaction and the Pauli principle.


title:
Construction of gauge invariant effective nucleonic theories: functional
  approach

abstract:
  Starting from relativistic quantum field theories, describing interacting
nucleons and pions coupled to the dynamical electromagnetic field, the pion
degrees of freedom are eliminated by means of functional integration. Apart
from taking into account some operators perturbatively in $e$, e.g. the vacuum
polarization, this procedure is exact, giving effective theories for nucleons
and photons. The subsequent nonrelativistic reduction yields the corresponding
nonrelativistic quantum field theory. The latter is unique, irrespective of the
precize form of the original nucleon-pion interaction. Nucleonic potentials and
electromagnetic interactions are mutually consistent. Local gauge invariance is
satisfied at any stage of the formal developments.


title:
Experimental and Computer Simulation Study of the Radionuclides Produced
  in Thin Bi-209 Targets by 130 MeV and 1.5 GeV Protons

abstract:
  The results of experimental and computer simulation studies of the yields of
residual product nuclei in Bi-209 thin targets irradiated by 130 MeV and 1.5
GeV protons are presented. The yields were measured by direct high-precision
gamma-spectrometry. The gamma-spectrometer resolution was 1.8 keV in the 1332
keV line. The gamma-spectra were processed by the ASPRO code. The gamma-lines
were identified, and the cross sections defined, by the SIGMA code using the
GDISP radioactive database. The process was monitored by the Al-27(p,x)Na-24
reaction. Results are presented for comparisons between the 209-Bi(p,x)
reaction yields obtained experimentally and simulated by the HETC, GNASH,
LAHET, INUCL, CEM95, CASCADE, and ALICE codes.


title:
Relativistic quantum kinetic equation of the Vlasov type for systems
  with internal degrees of freedom

abstract:
  We present an approach to derive a relativistic kinetic equation of the
Vlasov type. Our approach is especially reliable for the description of quantum
field systems with many internal degrees of freedom. The method is based on the
Heisenberg picture and leads to a kinetic equation which fulfills the
conservation laws. We apply the approach to the standard Walecka Lagrangian and
an effective chiral Lagrangian.


title: Scalar correlations in a quark plasma and low mass dilepton production

abstract:
  We investigate possible consequences of resonant scalar interactions for
dilepton production from a quark plasma at the chiral phase transition. It is
found that this production mechanism is strongly suppressed compared to the
Born process and has no significance for present experiments.


title: Sign convention of residues in QCD sum rules

abstract:
  We show that signs of pole residues $\lambda_N, \lambda_\Lambda,
\lambda_\Sigma, \lambda_\Xi$ for ${1\over2}^+$ octet baryons are identical in
the QCD sum rule approach. To do this we compare signs of meson-baryon coupling
constants $ g_{KN \Lambda}, g_{KN \Sigma}$, $g_{\pi \Lambda \Sigma}$ and
$g_{K\Lambda \Xi}$ each other.


title: Thermodynamic Properties of the SU(2)$_f$ Chiral Quark-Loop Soliton

abstract:
  We consider a chiral one-loop hedgehog soliton of the bosonized SU(2)$_f$
Nambu & Jona-Lasinio model which is embedded in a hot medium of constituent
quarks. Energy and radius of the soliton are determined in self-consistent
mean-field approximation. Quasi-classical corrections to the soliton energy are
derived by means of the pushing and cranking approaches. The corresponding
inertial parameters are evaluated. It is shown that the inertial mass is
equivalent to the total internal energy of the soliton. Corrected nucleon and
$\Delta$ isobar masses are calculated in dependence on temperature and density
of the medium. As a result of the self-consistently determined internal
structure of the soliton the scaling between constituent quark mass, soliton
mass and radius is noticeably disturbed.


title: Time-dependent relativistic mean-field theory

abstract:
  The relativistic mean-field theory provides a framework in which the nuclear
many-body problem is described as a self-consistent system of nucleons and
mesons. In the mean-field approximation, the self-consistent time evolution of
the nuclear system describes the dynamics of collective motion: double giant
resonances, nuclear compressibility from monopole resonances, regular and
chaotic dynamics of isoscalar and isovector collective vibrations.


title: The potential of effective field theory in NN scattering

abstract:
  We study an effective field theory of interacting nucleons at distances much
greater than the pion's Compton wavelength. In this regime the NN potential is
conjectured to be the sum of a delta function and its derivatives. The question
we address is whether this sum can be consistently truncated at a given order
in the derivative expansion, and systematically improved by going to higher
orders. Regularizing the Lippmann-Schwinger equation using a cutoff we find
that the cutoff can be taken to infinity only if the effective range is
negative. A positive effective range---which occurs in nature---requires that
the cutoff be kept finite and below the scale of the physics which has been
integrated out, i.e. O(m_\pi). Comparison of cutoff schemes and dimensional
regularization reveals that the physical scattering amplitude is sensitive to
the choice of regulator. Moreover, we show that the presence of some regulator
scale, a feature absent in dimensional regularization, is essential if the
effective field theory of NN scattering is to be useful. We also show that one
can define a procedure where finite cutoff dependence in the scattering
amplitude is removed order by order in the effective potential. However, the
characteristic momentum in the problem is given by the cutoff, and not by the
external momentum. It follows that in the presence of a finite cutoff there is
no small parameter in the effective potential, and consequently no systematic
truncation of the derivative expansion can be made. We conclude that there is
no effective field theory of NN scattering with nucleons alone.


title: Compton Scattering and the Spin Structure of the Nucleon at Low Energies

abstract:
  We analyze polarized Compton scattering which provides information on the
spin-structure of the nucleon. For scattering processes with photon energies up
to 100 MeV the spin-structure dependence can be encoded into four independent
parameters-the so-called spin-polarizabilities $\gamma_i, i=1...4$ of the
nucleon, which we calculate within the framework of the "small scale expansion"
in SU(2) baryon chiral perturbation theory. Specific application is made to
"forward" and "backward" spin- polarizabilities.


title: The Nuclear Spin-Orbit Force in Chiral Effective Field Theories

abstract:
  A compelling feature of relativistic mean-field phenomenology has been the
reproduction of spin-orbit splittings in finite nuclei after fitting only to
equilibrium properties of infinite nuclear matter. This successful result
occurs when the velocity dependence of the equivalent central potential that
leads to saturation arises primarily because of a reduced nucleon effective
mass. The spin-orbit interaction is then also specified when one works in a
four-component Dirac framework. Here the nature of the spin-orbit force in more
general chiral effective field theories of nuclei is examined, with an emphasis
on the role of the tensor coupling of the isoscalar vector meson (omega) to the
nucleon.


title: Periodic-Orbit Bifurcation and Shell Structure at Exotic Deformation

abstract:
  By means of periodic orbit theory and deformed cavity model, we have
investigated semiclassical origin of superdeformed shell structure and also of
reflection-asymmetric deformed shapes. Systematic analysis of quantum-classical
correspondence reveals that bifurcation of equatorial orbits into
three-dimensional ones play predominant role in the formation of these shell
structures.


title:
Regularization and renormalization in effective field theories of the
  nucleon-nucleon interaction

abstract:
  Some form of nonperturbative regularization is necessary if effective field
theory treatments of the NN interaction are to yield finite answers. We discuss
various regularization schemes used in the literature. Two of these methods
involve formally iterating the divergent interaction and then regularizing and
renormalizing the resultant amplitude. Either a (sharp or smooth) cutoff can be
introduced, or dimensional regularization can be applied. We show that these
two methods yield different results after renormalization. Furthermore, if a
cutoff is used, the NN phase shift data cannot be reproduced if the cutoff is
taken to infinity. We also argue that the assumptions which allow the use of
dimensional regularization in perturbative EFT calculations are violated in
this problem. Another possibility is to introduce a regulator into the
potential before iteration and then keep the cutoff parameter finite. We argue
that this does not lead to a systematically-improvable NN interaction.


title:
Multipole analysis of pion photoproduction based on fixed t dispersion
  relations and unitarity

abstract:
  We have analysed pion photoproduction imposing constraints from fixed t
dispersion relations and unitarity. Coupled integral equations for the S and P
wave multipoles were derived from the dispersion relations and solved by the
method of Omnes and Muskhelishvili. The free parameters were determined by a
fit to the most recent data for \pi^{+} and \pi^{0} production on the proton as
well as \pi^{-} production on the neutron, in the energy We have analysed pion
photoproduction imposing constraints from fixed t dispersion relations and
unitarity. Coupled integral equations for the S and P wave multipoles were
derived from the dispersion relations and solved by the method of Omnes and
Muskhelishvili. The free parameters were determined by a fit to the most recent
data for \pi^{+} and \pi^{0} production on the proton as well as \pi^{-}
production on the neutron, in the energy range 160 MeV \leq E_{\gamma} \leq 420
MeV. The lack of high precision data on the neutron and of polarization
observables leads to some limitations of our results. Especially the multipole
M_{1-} connected with the Roper resonance P_{11}(1440) cannot be determined to
the required precision. Our predictions for the threshold amplitudes are in
good agreement with both the data and chiral perturbation theory. In the region
of the \Delta(1232) we have determined the ratio of electric quadrupole and
magnetic dipole excitation. The position of the resonance pole is obtained in
excellent agreement with pion-nucleon scattering, and the complex residues of
the multipoles are determined with the speed-plot technique.


title: Anharmonic phonon excitations in subbarrier fusion reactions

abstract:
  Recently measured high precision data of fusion excitation function have
enabled a detailed study on the effects of nuclear collective excitations on
fusion reactions. Using such highly accurate data of the $^{16}$O +
$^{144,148}$Sm reactions, we discuss the anharmonic properties of collective
phonon excitations in $^{144,148}$Sm nuclei. It is shown that subbarrier fusion
reactions are strongly affected by the anharmonic effects and thus offer an
alternative method to extract the static quadrupole moments of phonon states in
a spherical nucleus.


title:
Isospin Breaking Effects in the Extraction of Isoscalar and Isovector
  Spectral Functions From $e^+e^-\to hadrons$

abstract:
  We investigate the problem of the extraction of the isovector and isoscalar
spectral functions from data on $e^+e^-\to hadrons$, in the presence of
non-zero isospin breaking. It is shown that the conventional approach to
extracting the isovector spectral function in the $\rho$ resonance region, in
which only the isoscalar contribution associated with $\omega\to \pi\pi$ is
subtracted, fails to fully remove the effects of the isoscalar component of the
electromagnetic current. The additional subtractions required to extract the
pure isovector and isoscalar spectral functions are estimated using results
from QCD sum rules. It is shown that the corrections are small ($\sim 2%$) in
the isovector case (though relevant to precision tests of CVC), but very large
($\sim 20%$) in the case of the $\omega$ contribution to the isoscalar spectral
function. The reason such a large effect is natural in the isoscalar channel is
explained, and implications for other applications, such as the extraction of
the sixth order chiral low-energy constant, $Q$, are discussed.


title:
Effects of core degrees of freedom in the low energy
  $^7$Be$(p,\gamma)^8$B reaction

abstract:
  Quadrupole and octupole couplings to all bound states of $^7$Be are included
in describing the capture reaction $^7$Be$(p,\gamma)^8$B. We verify, contrary
to what we had initially stated, that the energy behaviour of the Astrophysical
S-factor in the energy range of interest is not significantly sensitive to the
core couplings in the g.s. (g.s.) of $^8$B although its overall magnitude is
shifted. We find there is some sensitivity to the various deformation models
when introducing the nuclear interaction for calculating the scattering states.
The various deformation models predict quite different contributions to the
quadrupole and magnetic moments but in order to compare with the data the
quadrupole and magnetic moment of $^7$Be need to be measured.


title:
Elastic Proton-Deuteron Backward Scattering: Relativistic Effects and
  Polarization Observables

abstract:
  The elastic proton-deuteron backward reaction is analyzed within a covariant
approach based on the Bethe-Salpeter equation with realistic meson-exchange
interaction. Lorentz boost and other relativistic effects in the cross section
and spin correlation observables, like tensor analyzing power and polarization
transfer etc., are investigated in explicit form. Results of numerical
calculations for a complete set of polarization observables are presented.


title:
Scalar and vector decomposition of the nucleon self-energy in the
  relativistic Brueckner approach

abstract:
  We investigate the momentum dependence of the nucleon self-energy in nuclear
matter. We apply the relativistic Brueckner-Hartree-Fock approach and adopt the
Bonn A potential. A strong momentum dependence of the scalar and vector
self-energy components can be observed when a commonly used pseudo-vector
choice for the covariant representation of the T-matrix is applied. This
momentum dependence is dominated by the pion exchange. We discuss the problems
of this choice and its relations to on-shell ambiguities of the T-matrix
representation. Starting from a complete pseudo-vector representation of the
T-matrix, which reproduces correctly the pseudo-vector pion-exchange
contributions at the Hartree-Fock level, we observe a much weaker momentum
dependence of the self-energy. This fixes the range of the inherent uncertainty
in the determination of the scalar and vector self-energy components. Comparing
to other work, we find that extracting the self-energy components by a fit to
the single particle potential leads to even more ambiguous results.


title: Nuclear kaon dynamics

abstract:
  An effective low energy Lagrangian density is applied to nuclear
$K^-$-dynamics. The free parameters, local s-wave couplings and SU(3)-symmetry
constrained range terms are adjusted to describe elastic and inelastic
$K^-$-nucleon scattering data. The propagation and decay of the
$\Lambda(1405)$-resonance and the $\Lambda(1405)$-nucleon hole state is studied
self consistently with respect to the $K^-$-propagation in isospin symmetric
nuclear matter.


title:
Nucleon Sigma Term and In-medium Quark Condensate in the Modified
  Quark-Meson Coupling Model

abstract:
  We evaluate the nucleon sigma term and in-medium quark condensate in the
modified quark-meson coupling model which features a density-dependent bag
constant. We obtain a nucleon sigma term consistent with its empirical value,
which requires a significant reduction of the bag constant in the nuclear
medium similar to those found in the previous works. The resulting in-medium
quark condensate at low densities agrees well with the model independent linear
order result. At higher densities, the magnitude of the in-medium quark
condensate tends to increase, indicating no tendency toward chiral symmetry
restoration.


title: Asymmetrical and Non-equilibrium Expansion of Pion Gas Created in HIC

abstract:
  Results of the computer simulation of dilepton production from the expanding
pion gas created in ultrarelativistic Pb+Pb 160 GeV/n collisions are presented.
Finite size of the expanding pion gas influences invariant mass spectrum of
dileptons. Sensitivity of the shape of dilepton mass spectrum to the initial
stage of the pion gas is discussed. Second order asymmetry in azimuthal
distribution of dileptons is predicted for non-central collisions.
Non-equilibrium nature of the pion gas expansion is found to exhibit itself in
rapidity distribution of produced dilepton pairs.


title: Jost Function for Coupled Partial Waves

abstract:
  An exact method for direct calculation of the Jost functions and Jost
solutions for non-central potentials which couple partial waves of different
angular momenta is presented. A combination of the variable-constant method
with the complex coordinate rotation is used to replace the matrix
Schr\"odinger equation by an equivalent system of linear first--order
differential equations. Solving these equations numerically, the Jost functions
can be obtained to any desired accuracy for all complex momenta of physical
interest, including the spectral points corresponding to bound and resonant
states. The effectiveness of the method is demonstrated using the Reid
soft-core and Moscow nucleon-nucleon potentials which involve tensor forces.


title: Nuclear Many-Body Problem at Finite Temperature: A TFD Approach

abstract:
  Based on the formalism of thermo-field dynamics a new approach for studying
collective excitations in hot finite Fermi systems is presented. Two
approximations going beyond the thermal RPA namely renormalized thermal RPA and
thermal second RPA are formulated.


title:
Polarization degrees of freedom in photoinduced two-nucleon knockout
  from finite nuclei

abstract:
  The polarization degrees of freedom in photoinduced two-nucleon knockout from
finite nuclei are studied. It is pointed out that they open good perspectives
to study the dynamics of dinucleons in the medium in detail. The ($\gamma,pp$)
and ($\gamma,pn$) angular cross sections, photon asymmetries and outgoing
nucleon polarizations are calculated for the target nuclei $^{16}$O and
$^{12}$C and photonenergies ranging from 100 up to 500 MeV. It is investigated
to which degree the two-nucleon emission reaction is dominated by
photoabsorption on $^3S_1(T=0)$ proton-neutron and $^1S_0(T=1)$ proton-proton
pairs in the nuclear medium. The calculations demonstrate that dominance of $S$
wave photoabsorption in the ($\gamma,pn$) channel does not necessarily imply
that the reaction mechanism is similar to what is observed in deuteron
photodisintegration.


title:
Large Amplitude Collective Motion in Nuclei and Metallic Clusters:
  Applicability of adiabatic theory for a pairing model

abstract:
  A model Hamiltonian describing a two-level system with a crossing plus a
pairing force is investigated using technique of large-amplitude collective
motion. The collective path, which is determined by the decoupling conditions,
is found to be almost identical to the one in the Born-Oppenheimer
approximation for the case of a strong pairing force. For the weak pairing
case, the obtained path describes a diabatic dynamics of the system.


title:
Nuclear dependence of the coherent eta photoproduction reaction in a
  relativistic approach

abstract:
  We study the nuclear (or A) dependence of the coherent eta photoproduction
reaction in a relativistic impulse approximation approach. We use a standard
relativistic parameterization of the elementary amplitude, based on a set of
four Lorentz- and gauge-invariant amplitudes, to calculate the coherent
production cross section from He-4, C-12, and Ca-40. In contrast to
nonrelativistic treatments, our approach maintains the full relativistic
structure of the process. The nuclear structure affects the process through the
ground-state tensor density. This density is sensitive to relativistic effects
and depends on A in a different manner than the vector density used in
nonrelativistic approaches. This peculiar dependence results in He-4 having a
cross section significantly smaller than that of C-12---in contrast to existent
nonrelativistic calculations. Distortion effects are incorporated through an
eta-nucleus optical potential that is computed in a simple ``t rho''
approximation.


title:
Signals of quark substructure in hadron reactions at intermediate
  energies

abstract:
  Exotic hadrons of a few GeV/c^2 mass, exhibiting a spectrum determined by the
perturbative interaction of a non-minimal number of valence quarks, have long
been predicted as signals of the underlying QCD structure. Models that include
the confinement region, in addition to the region of asymptotic freedom,
predict exotic masses 0.2--0.8 GeV higher than the others. The R-matrix hybrid
model has made the most detailed predictions, some of which have been
experimentally observed. Here we will give an introduction to the model and
review the status of its predictions and new applications.


title:
Analysis of the thermal cross section of the capture reaction
  13C(n,gamma)14C

abstract:
  We investigate the thermal cross section of the reaction 13C(n,gamma)14}C
which takes place in the helium burning zones of red giant star as well as in
the nucleosynthesis of Inhomogeneous Big Bang models. We find that we can
reproduce the experimentally known thermal capture cross section only if we
take into account a strong hindrance of the E1 transition in the nuclear
interior. This effect can be explained by the strong coupling to the giant
dipole resonance.


title:
Hadrons in Dense Matter and Medium Effects in Relativistic Heavy-Ion
  Collisions

abstract:
  Theoretical and experimental studies of hot and/or dense matter, such as is
created in high-energy heavy-ion collisions, and encountered in compact objects
in astrophysics, constitute one of the most active frontiers in nuclear
physics. In these Lectures, we discuss various approaches to the description of
hot and/or dense matter, including the simple Skyrme-type parameterization and
relativistic Walecka-type models, as well as microscopic Dirac-Brueckner and
QCD sum rule approaches. As density and/or temperature of the hadronic system
increases, chiral symmetry is gradually restored, as indicated by the decrease
of quark condensate. This has profound effects on the properties of hadrons,
especially their masses. We review various theoretical predictions for hadron
properties in dense matter. Experimentally, possible medium modifications of
hadron properties can be studied through the measurements of particle spectra,
flow, and particularly, electromagnetic observables. Particle production,
especially the production of rare particles such as kaons, vector mesons, and
antiparticles, provides useful insight into heavy-ion collision dynamics, and
hadron properties in dense matter. Collective flows of various kinds are
important observables in heavy-ion collisions. They probe essentially the
entire reaction process, and thus are very useful for the determination of the
reaction dynamics. They also reflect the properties of hadrons in dense matter.
Electromagnetic signals are considered penetrating probes that may carry
undistorted information about the early stage of high-energy heavy-ion
collisions. We discuss various theoretical calculations of dilepton and photon
production in heavy-ion collisions at SPS energies and various medium effects
that have been proposed to explain the observed low-mass dilepton enhancement.


title: Electromagnetic interactions for the two-body spectator equations

abstract:
  This paper presents a new non-associative algebra which is used to (i) show
how the spectator (or Gross) two-body equations and electromagnetic currents
can be formally derived from the Bethe-Salpeter equation and currents if both
are treated to all orders, (ii) obtain explicit expressions for the Gross
two-body electromagnetic currents valid to any order, and (iii) prove that the
currents so derived are exactly gauge invariant when truncated consistently to
any finite order. In addition to presenting these new results, this work
complements and extends previous treatments based largely on the analysis of
sums of Feynman diagrams.


title: Central Coulomb Effects on Pion Interferometry

abstract:
  Using a simple final-state rescattering model coupled with a simple Coulomb
model, the effects of the central Coulomb potential on pion interferometry
measurements in 158 GeV/nucleon Pb+Pb collisions are explored. Although the
central Coulomb potential does not introduce correlations between pions, it
does prevent an accurate measurement of the momentum difference. This momentum
difference smearing effect leads to a reduction in the measured correlation
radii and lambda parameters. These distortions are important in 158 GeV/nucleon
Pb+Pb collisions because of large source sizes and the strong central Coulomb
potential.


title: Pseudo-spin Symmetry and Relativistic Single-nucleon Wave Functions

abstract:
  We show that the occurrence of approximate pseudo-spin symmetry in nuclei is
connected with certain similarities in the relativistic single-nucleon wave
functions of the corresponding pseudo-spin doublets. We perform a case study in
which several examples and the systematics of this connection are explored.


title:
Quantum Kinetics of Deconfinement Transitions in Dense Nuclear Matter:
  Dissipation Effects at Low Temperatures

abstract:
  Effects of energy dissipation on quantum nucleation of two-flavor quark
matter in dense nuclear matter encountered in neutron star cores are examined
at low temperatures. We find that low-energy excitations of nucleons and
electrons reduce the nucleation rate exponentially via their collisions with
the surface of a quark matter droplet.


title:
Relativistic Hartree-Bogoliubov description of the neutron drip-line in
  light nuclei

abstract:
  The Relativistic Hartree Bogoliubov theory is applied in the mean-field
approximation to the description of properties of light nuclei with large
neutron excess. Pairing correlations and the coupling to particle continuum
states are described by finite range two-body forces. Using standard parameter
sets for the mean-field Lagrangian and the pairing interaction of Gogny-type,
self-consistent solutions in coordinate space are calculated for the ground
states of a number of neutron-rich nuclei. The model predicts the location of
the neutron drip-line, reduction of the spin-orbit interaction, $rms$ radii,
changes in surface properties, the formation of neutron skin and of neutron
halo.


title: Thermodynamics of Delta resonances

abstract:
  The thermodynamic potential of a system of pions and nucleons is computed
including the piN interactions in the P33 channel. A consistent treatment of
the width of the resonance in this channel, the Delta(1232) resonance, is
explored in detail. In the low-density limit we recover the leading term of the
virial expansion for the thermodynamic potential. An instructive diagrammatic
interpretation of the contributions to the total baryon number is presented.
Furthermore, we examine within a fireball model the consequences for the pion
spectra in heavy-ion collisions at intermediate energies, including the effect
of collective flow. A consistent treatment of the Delta width leads to a
substantial enhancement of the pion yield at low momenta.


title: A statistical approach to the theory of the mean field

abstract:
  We develop a statistical theory of the mean field. It is based on the
proposition that the mean field can be obtained as an energy average. Moreover,
it is assumed that the matrix elements of the residual interaction are random
with the average value of zero. Explicit expressions for the mean field and the
fluctuation away from the average are obtained. The fluctuation is expanded in
terms of more and more complex excitations. Using the randomness of the matrix
elements one can then obtain formulas for the contribution to the error from
each class of complex excitations and a general condition for the convergence
of the expansion is derived. Making some simplifying assumptions a schematic
model is developed and applied to the problem of nuclear matter. It yields a
measure of the strength of the effective interaction. The latter turns out to
be three orders of magnitude less than that calculated using a potential which
gives a binding energy of about -7 MeV/nucleon demonstrating the strong damping
of the interaction strength induced by the averaging process.


title: Electromagnetic and Strong Decays in a Collective Model of the Nucleon

abstract:
  We present an analysis of electromagnetic elastic form factors, helicity
amplitudes and strong decay widths of non-strange baryon resonances, within a
collective model of the nucleon. Flavor-breaking and stretching effects are
considered. Deviations from the naive three-constituents description are
pointed out.


title: A new evaluation of the Baldin sum rule

abstract:
  The Baldin sum rule for the nucleon has been recalculated at the light of the
most recent photoabsorption cross section measurements. The proton value (alpha
+ beta)_p =13.69 +/- 0.14 is smaller but consistent with the one usually quoted
in literature. However, the value for the neutron (alpha + \beta)_n =14.40 +/-
0.66 turns out to be three standard deviations away from the previously
calculated one.


title: Liquid-gas phase transition in finite nuclei

abstract:
  In a finite temperature Thomas-Fermi framework, we calculate density
distributions of hot nuclei enclosed in a freeze-out volume of few times the
normal nuclear volume and then construct the caloric curve, with and without
inclusion of radial collective flow. In both cases, the calculated specific
heats $C_v$ show a peaked structure signalling a liquid-gas phase transition.
Without flow, the caloric curve indicates a continuous phase transition whereas
with inclusion of flow, the transition is very sharp. In the latter case, the
nucleus undergoes a shape change to a bubble from a diffuse sphere at the
transition temperature.


title: On the Relativistic Foundations of Pseudospin Symmetry in Nuclei

abstract:
  We show that the generators of pseudospin symmetry are the non - relativistic
limit of the generators of an SU(2) symmetry which leaves invariant the Dirac
Hamiltonian with scalar and vector potentials equal in magnitude but opposite
in sign, $V_V = - V_S$. Furthermore, within this framework, we demonstrate that
this symmetry may be approximately conserved for realistic scalar and vector
potentials.


title: Sensitivity of the deuteron form factor to nucleon resonances

abstract:
  The sensitivity of the deuteron form factor to contributions from the excited
states of the nucleon is explored using a simple model of the nucleon-nucleon
interaction which employs a tower of charged nucleon resonances. The model is
manifestly covariant, analytically solvable, and gauge invariant. The
consequences of this model are studied in the simplest possible framework. We
assume that all particles have spin zero and that the tower has only three
charged members, which consist of the proton, the Roper, and a higher state in
the vicinity of the $D_{13}$. Nucleon-nucleon S-wave phase shifts and the
deuteron form factor are calculated using this three member tower, and the
results are compared to similar calculations using the proton ground state
only. We conclude that the deuteron form factor is insensitive to the presence
of excited states of the proton unless those states are of sufficiently low
mass to produce strong inelasticities in $NN$ scattering channels.


title:
A self-consistent approach to the Wigner-Seitz treatment of soliton
  matter

abstract:
  We propose a self-consistant approach to the treatment of nuclear matter as a
crystal of solitons in the Wigner-Seitz approximation. Specifically, we use a
Bloch-like boundary condition on the quarks at the edge of a spherical cell
which allows the dispersion relation for a given radius to be calculated
self-consistently along with the meson fields; in previous work some ansatz for
the dispersion relation has always been an input. Results in all models are
very sensitive to the form of the dispersion relation, so our approach
represents a significant advance. We apply the method to both the Friedberg Lee
model and the chiral quark-meson model of Birse and Banerjee. Only the latter
shows short range repulsion; in the former the transition to a quark plasma
occurs at unrealistically low densities.


title: j_psi Suppression and the Quark-Gluon Plasma

abstract:
  All measured Feynman x_f distributions of the ratio, R, of j_psi production
in nuclei relative to production on protons fall off with x_f.
  They show [2] that absorption of charmonium cannot be the only source of
j_psi suppression and that energy loss of the constituents of the incident
proton prior to the j_psi production, because of the exponential sqrt(s)
dependence of the charmonium cross section, should not be neglected. Including
the effects of initial state energy loss we find that the latest measured
  Pb-Pb j_psi cross sections do not provide any evidence for deconfinement.


title: Rotational Bands at the Limit of Angular Momentum

abstract:
  The properties of rotational bands at the limit of angular momentum are
discussed on the example of smooth terminating bands observed in the A~110 mass
region. The effective alignment approach is used for the study of their
relative properties which provides additional insight into the properties of
such bands.


title: Relative Properties of Smooth Terminating Bands

abstract:
  The relative properties of smooth terminating bands observed in the A~110
mass region are studied within the effective alignment approach. Theoretical
values of $i_{eff}$ are calculated using the configuration-dependent
shell-correction model with the cranked Nilsson potential. Reasonable agreement
with experiment shows that previous interpretations of these bands are
consistent with the present study. Contrary to the case of superdeformed bands,
the effective alignments of these bands deviate significantly from the pure
single-particle alignments < j_x > of the corresponding orbitals. This
indicates that in the case of smooth terminating bands, the effects associated
with changes in equilibrium deformations contribute significantly to the
effective alignment.


title:
Cranked Relativistic Mean Field Description of Superdeformed Rotational
  Bands

abstract:
  The cranked relativistic mean field theory is applied for a detailed
investigation of eight superdeformed rotational bands observed in $^{151}$Tb.
It is shown that this theory is able to reproduce reasonably well not only the
dynamic moments of inertia $J^{(2)}$ of the observed bands but also the
alignment properties of the single-particle orbitals.


title: Collision Broadening of the Phi Meson in Baryon Rich Hadronic Matter

abstract:
  Phi meson-baryon cross sections, estimated within a one-boson-exchange model,
serve as input for a calculation of the collision rates in hot hadronic matter.
We find that the width of the \phi meson is modified through collisions with
baryons by 1-10 MeV at 160 MeV temperature depending on the baryon fugacity.
Thermalization of the \phi in high energy heavy ion collisions is discussed.


title: Broken Pairs and High-Spin States in Transitional Nuclei

abstract:
  The Interacting Boson plus broken-pairs Model has been used to describe
high-spin bands in spherical and transitional nuclei. In the spherical nucleus
$^{104}$Cd the model reproduces the structure of high-spin bands built on a
vibrational structure. Model calculations performed with a single set of
parameters reproduce ten bands in $^{136}$Nd, including the two dipole
high-spin bands based on the $(\pi h_{11/2})^2$ $(\nu h_{11/2})^2$
configuration.


title: Signature and Angular Momentum in 3d-Cranked HFB states

abstract:
  In terms of the exaxt angular momentum projection, properties of the three
dimensional cranked HFB (3d-CHFB) states are analyzed quantitatively in the
context of the relation between the signature of an intrinsic symmetry and the
parity of angular momentum, (-1)^I. We found that the tilted states have
favorable features to describe states involved with high-K quantum number
and/or odd total angular momentum. This implies that 3d-CHFB can describe
properly the backbending phenomena like a "t-band and g-band" crossing, which
is suggested in N=106 isotopes.


title: Dispersion relations and the spin polarizabilities of the nucleon

abstract:
  A forward dispersion calculation is implemented for the spin polarizabilities
$\gamma_1, ... ,\gamma_4$ of the proton and the neutron. These polarizabilities
are related to the spin structure of the nucleon at low energies and are
structure-constants of the Compton scattering amplitude at ${\cal
O}(\omega^3)$. In the absence of a direct experimental measurement of these
quantities, a dispersion calculation serves the purpose of constraining the
model building, and of comparing with recent calculations in heavy baryon
chiral perturbation theory.


title:
Influence of pion-delta-hole configuration on the rho meson mass
  spectrum in dense hadronic matter

abstract:
  We discuss medium modification of the rho meson originating from its coupling
to in medium quasi-pions and delta-hole states. This medium effect leads to a
marked structure of the rho meson strength function in the $500 MeV$ invariant
mass region. We suggest that this effect may provide an explanation of the
structure observed by the DLS collaboration in the $Ca+Ca/C+C$ ratio at $1
GeV/u$.


title: Shell Effects in Mesoscopic Systems

abstract:
  The main aim of the results presented here is to demonstrate and analyse the
importance of shell effects in nuclei, metallic clusters and quantum dots.


title: K^+ production in baryon-baryon and heavy-ion collisions

abstract:
  Kaon production cross sections in nucleon-nucleon, nucleon-delta and
delta-delta interactions are studied in a boson exchange model. For the latter
two interactions, the exchanged pion can be on-mass shell, only contributions
due to a virtual pion are included via the Peierls method by taking into
account the finite delta width. With these cross sections and also those for
pion-baryon interactions, subthreshold kaon production from heavy ion
collisions is studied in the relativistic transport model.


title:
On the role of the effective interaction in quasi-elastic electron
  scattering calculations

abstract:
  The role played by the effective residual interaction in the transverse
nuclear response for quasi-free electron scattering is discussed. The analysis
is done by comparing different calculations performed in the Random--Phase
Approximation and Ring Approximation frameworks. The importance of the exchange
terms in this energy region is investigated and the changes on the nuclear
responses due to the modification of the interaction are evaluated. The
calculated quasi-elastic responses show clear indication of their sensibility
to the details of the interaction and this imposes the necessity of a more
careful study of the role of the different channels of the interaction in this
excitation region.


title: On the Gerasimov-Drell-Hearn sum rule for the deuteron

abstract:
  The Gerasimov-Drell-Hearn sum rule is evaluated for the deuteron by explicit
integration up to 550 MeV including contributions from the photodisintegration
channel and from coherent and incoherent single pion production as well. The
photodisintegration channel converges fast enough in this energy range and
gives a large negative contribution, essentially from the $^1S_0$ resonant
state near threshold. Its absolute value is about the same size as the sum of
proton and neutron GDH values. It is only partially cancelled by the single
pion production contribution. But the incoherent channel has not reached
convergence at 550 MeV.


title:
Explicit pionic degrees of freedom in deuteron photodisintegration in
  the Delta-resonance region

abstract:
  Photodisintegration of the deuteron above pi-threshold is studied in a
coupled channel approach including N-Delta- and pi-d-channels with pion
retardation in potentials and exchange currents.


title:
Dispersion Theoretical Analysis of Pion Photoproduction at Threshold and
  in the Delta Region

abstract:
  A new partial wave analysis of pion photoproduction has been obtained in the
framework of fixed-t dispersion relations valid form threshold up to 500 MeV.
It is based on new Mainz data for \pi^{0} and \pi^{+} production off the proton
and both older and more recent data from Bonn, Frascati and TRIUMF for \pi^{+}
and \pi^{-}. At threshold we obtain a good agreement with the existing data for
both charged and neutral pion production. In the resonance region we have
precisely determined the electromagnetic properties of the \Delta(1232)
resonance, in particular the E2/M1 ratio R_{EM}=(-2.5 \pm 0.1) %. We show that
a model independent resonance background subtraction is possible with the
speed-plot technique and obtain the \Delta pole at W =(1211 - 50i) MeV and the
E2/M1 ratio of the residues as R_{\Delta} = - 0.035 - 0.046 i.


title: Diabatic and Adiabatic Collective Motion in a Model Pairing System

abstract:
  Large amplitude collective motion is investigated for a model pairing
Hamiltonian containing an avoided level crossing. A classical theory of
collective motion for the adiabatic limit is applied utilising either a
time-dependent mean-field theory or a direct parametrisation of the
time-dependent Schr\"odinger equation. A modified local harmonic equation is
formulated to take account of the Nambu-Goldstone mode. It turns out that in
some cases the system selects a diabatic path. Requantizing the collective
Hamiltonian, a reasonable agreement with an exact calculation for the low-lying
levels are obtained for both weak and strong pairing force. This improves on
results of the conventional Born-Oppenheimer approximation.


title:
Analysis of factorization in (e,e'p) reactions: A survey of the
  relativistic plane wave impulse approximation

abstract:
  The issue of factorization within the context of coincidence quasi-elastic
electron scattering is reviewed. Using a relativistic formalism for the entire
reaction mechanism and restricting ourselves to the case of plane waves for the
outgoing proton, we discuss the meaning of factorization in the cross section
and the role of the small components of the bound nucleon wave function.


title: Gauging hadronic systems

abstract:
  We present a general method for incorporating the electromagnetic interaction
into descriptions of hadronic processes based on four-dimensional scattering
integral equations. The method involves the idea of gauging the scattering
equations themselves, and results in electromagnetic amplitudes where an
external photon is effectively coupled to every part of every strong
interaction diagram in the model. Current conservation is therefore implemented
in the theoretically correct fashion. To illustrate our gauging procedure we
apply it to the three-nucleon problem whose strong interactions are described
by standard three-body integral equations. In this way we obtain the
expressions needed to calculate all possible electromagnetic processes of the
three-nucleon system: the electromagnetic form factors of the three-body bound
state, pd->pd gamma, gamma 3He-> pd, gamma 3He-> ppn, etc. As the photon is
coupled everywhere in the strong interaction model, a unified description of
the NNN-gamma NNN system is obtained. An interesting aspect of our results is
the natural appearance of a subtraction term needed to avoid the overcounting
of diagrams.


title:
A Dynmical study of Fission Process and estimation of Prescission
  Neutron Multiplicity

abstract:
  The dynamics of fission has been studied by solving Euler-Lagrange equation
with dissipation generated through one and two body nuclear friction. The
average kinetic energies of the fission fragments, prescission neutron
multiplicities and the mean energies of the prescission neutrons have been
calculated and compared with experimental values and they agree quite well. A
single value of friction coefficient has been used to reproduce the
experimental data for both symmetric and asymmetric splitting of the fissioning
systems over a wide range of masses and excitation energies. It has been
observed that a stronger friction is required in the saddle to scission region
as compared to that in the ground state to saddle region.


title:
Treatment of competition between complete fusion and quasifission in
  collisions of heavy nuclei

abstract:
  A model of competition between complete fusion and quasifission channels in
fusion of two massive nuclei is extended to include the influence of
dissipative effects on the dynamics of nuclear fusion. By using the
multidimensional Kramers-type stationary solution of the Fokker-Planck
equation, the fusion rate through the inner fusion barrier in mass asymmetry is
studied. Fusion probabilities in symmetric 90Zr+90Zr, 100Mo+100Mo, 110Pd+110Pd,
136Xe+136Xe, almost symmetric 86Kr+136Xe and 110Pd+136Xe reactions are
calculated. An estimation of the fusion probabilities is given for asymmetrical
62Ni+208Pb, 70Zn+208Pb, 82Se+208Pb, and 48Ca+244Pu reactions used for the
synthesis of new superheavy elements.


title:
Fusion cross sections for superheavy nuclei in the dinuclear system
  concept

abstract:
  Using the dinuclear system concept we present calculations of production
cross sections for the heaviest nuclei. The obtained results are in a good
agreement with the experimental data. The experimentally observed rapid
fall-off of the cross sections of the cold fusion with increasing charge number
$Z$ of the compound nucleus is explained. Optimal experimental conditions for
the synthesis of the superheavy nuclei are suggested.


title: Dilepton production and $m_T$-scaling at BEVALAC/SIS energies

abstract:
  We present a dynamical study of $e^+e^-$ production in C + C and Ca + Ca
collisions at BEVALAC/SIS energies on the basis of the covariant transport
approach HSD employing momentum-dependent $\rho$-meson spectral functions that
include the pion modifications in the nuclear medium as well as the
polarization of the $\rho$-meson due to resonant $\rho - N$ scattering. We find
that the experimental data from the DLS collaboration cannot be described
within the $\rho$-meson spectral function approach. A dropping $\eta$-mass
scenario leads to a good reproduction of the DLS dilepton data, however,
violates the $m_T$-scaling of $\pi^0$ and $\eta$ spectra as observed by the
TAPS collaboration as well as $\eta$ photoproduction on nuclei.


title:
Reanalysis of antiproton production in proton-nucleus and
  nucleus-nucleus reactions at subthreshold energies

abstract:
  We reanalyse the production of $p\bar{p}$ pairs in proton-nucleus and
nucleus-nucleus collisions employing novel elementary cross sections for
baryon-baryon and pion-baryon production channels based on a boson-exchange
model. In contrast to previous transport studies performed in the literature
the secondary pion induced channel is found to be most important in both p+A
and A+A collisions at subthreshold energies. A detailed comparison with the
experimental data available indicates that sizeable attractive $\bar{p}$
potentials in the order of - 100 to - 150 MeV at normal nuclear matter density
are needed to reproduce the size and shape of the experimental spectra.


title: Recent Results in Charged-Composite Particle Scattering

abstract:
  A brief overview is given of some recent advances in charged-composite
particle scattering. On the theoretical side, I address the three-charged
particle wave function asymptotics, the nonperturbative investigation of the
long-range behaviour of the optical potential, and the question of the
compactness of the kernels of the momentum space integral equations for three
charged particles. Among the more practical developments, I report on results
of numerical calculations of so-called "triangle" amplitudes, a new, simple and
very efficient higher-energy approximation for the latter, and a breakthrough
in the quantitative treatment of Coulomb effects in proton-deuteron elastic
scattering with realistic nuclear potentials.


title:
Nucleon-Antinucleon Interaction from the Skyrme Model: II. Beyond the
  Product Ansatz

abstract:
  We calculate the full static interaction of a Skyrmion and an anti-Skyrmion
as a function of separation and relative grooming. From this, using projection
methods and Born-Oppenheimer mixing, we obtain the nucleon antinucleon
interaction. We find agreement with the major features of the empirical
interaction including the strong central attraction and the sharp onset of
annihilation at about 1 fm.


title: On the Equation of State of Nuclear Matter in 158A GeV Pb+Pb Collisions

abstract:
  Within a hydrodynamical approach we investigate the sensitivity of single
inclusive momentum spectra of hadrons in 158A GeV Pb+Pb collisions to three
different equations of state of nuclear matter. Two of the equations of state
are based on lattice QCD results and include a phase transition to a
quark-gluon plasma. The third equation of state has been extracted from the
microscopic transport code RQMD under the assumption of complete local
thermalization. All three equations of state provide reasonable fits to data
taken by the NA44 and NA49 Collaborations. The initial conditions before the
evolution of the fireballs and the space-time evolution pictures differ
dramatically for the three equations of state when the same freeze-out
temperature is used in all calculations. However, the softest of the equations
of state results in transverse mass spectra that are too steep in the central
rapidity region. We conclude that the transverse particle momenta are
determined by the effective softness of the equation of state during the
fireball expansion.


title: Production and decay of the d* dibaryon

abstract:
  The production of the isoscalar Jp = 3+ didelta dibaryon d* by proton
inelastic scattering from deuteron targets is described in a double-scattering
Glauber approximation. Each scattering changes a target nucleon into a Delta
with the help of the isovector tensor force transmitted by pi and rho mesons.
The differential cross section constructed from empirical Love-Franey
nucleon-nucleon t-matrices and a simple model of d* shows a maximum of some 10
micro-b/sr at 70 deg (c.m.) for 500 MeV protons. The partial width of the decay
d* -> NN caused by the exchanges of the same mesons is found for this simple
model of d* to be about 9 MeV if the d* mass is 2100 MeV. The implications of
these results are discussed.


title: Masses and Deformations of Neutron-Rich Nuclei

abstract:
  We have calculated the masses, deformations, and other properties of 8979
nuclei ranging from oxygen-16 to Z = 136, A = 339 and extending from the proton
drip line to the neutron drip line on the basis of the 1992 version of the
finite-range droplet model. The predicted quantities include the ground-state
mass, deformation, microscopic correction, odd-proton and odd-neutron spins and
parities, proton and neutron pairing gaps, binding energy, one- and two-neutron
separation energies, quantities related to beta-delayed one- and two-neutron
emission probabilities, beta-decay energy release and half-life with respect to
Gamow-Teller decay, one- and two-proton separation energies, and alpha-decay
energy release and half-life. For 1654 nuclei heavier than oxygen-16 whose
masses were known experimentally in 1989 and which were included in the
adjustment of model constants, the theoretical error is 0.669 MeV. For 371
additional nuclei heavier than oxygen-16 whose masses have been measured
between 1989 and 1996 and which were not used in the adjustment of the model
constants, the theoretical error is 0.570 MeV.


title: Two-nucleon emission in the longitudinal response

abstract:
  The contribution of the two-nucleon emission in the longitudinal response for
inclusive electron scattering reactions is studied. The model adopted to
perform the calculations is based upon Correlated Basis Function theory but it
considers only first order terms in the correlation function. The proper
normalization of the wave function is ensured by considering, in addition to
the usually evaluated two-point diagrams, also the three-point diagrams.
Results for the 12C nucleus in the quasi-elastic region are presented.


title: Final state interactions in two-particle interferometry

abstract:
  We reconsider the influence of two-particle final state interactions (FSI) on
two-particle Bose-Einstein interferometry. We concentrate in particular on the
problem of particle emission at different times. Assuming chaoticity of the
source, we derive a new general expression for the symmetrized two-particle
cross section. We discuss the approximations needed to derive from the general
result the Koonin-Pratt formula. Introducing a less stringent version of the
so-called smoothness approximation we also derive a more accurate formula. It
can be implemented into classical event generators and allows to calculate FSI
corrected two-particle correlation functions via modified Bose-Einstein
"weights".


title:
Computer program for the relativistic mean field description of the
  ground state properties of even-even axially deformed nuclei

abstract:
  A Fortran program for the calculation of the ground state properties of
axially deformed even-even nuclei in the relativistic framework is presented.
In this relativistic mean field (RMF) approach a set of coupled differential
equations namely the Dirac equation with potential terms for the nucleons and
the Glein-Gordon type equations with sources for the meson and the
electromagnetic fields are to be solved self-consistently. The well tested
basis expansion method is used for this purpose. Accordingly a set of harmonic
oscillator basis generated by an axially deformed potential are used in the
expansion. The solution gives the nucleon spinors, the fields and level
occupancies, which are used in the calculation of the ground state properties.


title:
Boson mappings and four-particle correlations in algebraic
  neutron-proton pairing models

abstract:
  Neutron-proton pairing correlations are studied within the context of two
solvable models, one based on the algebra SO(5) and the other on the algebra
SO(8). Boson-mapping techniques are applied to these models and shown to
provide a convenient methodological tool both for solving such problems and for
gaining useful insight into general features of pairing. We first focus on the
SO(5) model, which involves generalized T=1 pairing. Neither boson mean-field
methods nor fermion-pair approximations are able to describe in detail
neutron-proton pairing in this model. The analysis suggests, however, that the
boson Hamiltonian obtained from a mapping of the fermion Hamiltonian contains a
pairing force between bosons, pointing to the importance of boson-boson (or
equivalently four-fermion) correlations with isospin T=0 and spin S=0. These
correlations are investigated by carrying out a second boson mapping. Closed
forms for the fermion wave functions are given in terms of the fermion-pair
operators. Similar techniques are applied -- albeit in less detail -- to the
SO(8) model, involving a competition between T=1 and T=0 pairing. Conclusions
similar to those of the SO(5) analysis are reached regarding the importance of
four-particle correlations in systems involving neutron-proton pairing.


title:
The energy dependence of the in-medium $\eta N$ cross section evaluated
  from $\eta$-photoproduction

abstract:
  Within the Glauber formalism and a BUU transport model we analyze the
$\eta$-photoproduction data from nuclei and evaluate the in-medium $\eta N$
cross section. Our results indicate that the $\eta N$ cross section is almost
independent of the $\eta$ energy up to 200 MeV.


title:
Interacting Boson Model plus broken-pairs description of high-spin
  dipole bands

abstract:
  The Interacting Boson Model with broken-pairs has been extended to include
mixed proton-neutron configurations in the fermion model space. The extended
version of the model has been used to describe high-spin bands in the
transitional nucleus $^{136}$Nd. Model calculations reproduce ten bands of
positive and negative parity states, including the two dipole high-spin
structures based on the $(\pi h_{11/2})^2$ $(\nu h_{11/2})^2$ configuration.


title:
The Question of Low-Lying Intruder States in $^8Be$ and Neighboring
  Nuclei

abstract:
  The presence of not yet detected intruder states in $^{8}Be$ e.g. a $J=2^{+}$
intruder at 9 $MeV$ excitation would affect the shape of the $\beta ^{\mp
}$-delayed alpha spectra of $^{8}Li$ and $^{8}B$. In order to test the
plausibility of this assumption, shell model calculations with up to $4\hbar
\omega $ excitations in $^{8}Be$ (and up to $2\hbar \omega $ excitations in
$^{10}Be$) were performed. With the above restrictions on the model spaces, the
calculations did not yield any low-lying intruder state in $^{8}Be$. Another
approach -the simple deformed oscillator model with self-consistent frequencies
and volume conservation gives an intruder state in $^{8}Be$ which is lower in
energy than the above shell model results, but its energy is still considerably
higher than 9 $MeV$.


title:
High-j Intruder Orbitals and the $\Delta I$ = 4 Bifurcation in
  Superdeformed Bands

abstract:
  All the known cases of the $\Delta I=4$ bifurcation in the SD bands are
analysed in the framework of the microscopic theory suggested by the author
[Phys. Rev. C 55 (1997) 1275]. It is shown that the intruder orbitals are of
paramount importance to the energy staggering.


title: Properties of Pairing Correlations in Infinite Nuclear Matter

abstract:
  We discuss various properties of singlet S pairing in neutron and nuclear
matter in terms of the bare nuclon-nucleon interaction. Relations to the NN
phase shifts are discussed, as well as various properties of the BCS wave
function and the coherence length for fermion superfluids in infinite matter.


title: Effect of Flow on Caloric Curve for Finite Nuclei

abstract:
  In a finite temperature Thomas-Fermi theory, we construct caloric curves for
finite nuclei enclosed in a freeze-out volume few times the normal nuclear
volume, with and without inclusion of flow. Without flow, the caloric curve
indicates a smooth liquid-gas phase transition whereas with flow, the
transition may be very sharp. We discuss these results in the context of two
recent experiments, one for heavy symmetric system (Au + Au at 600A MeV) and
the other for highly asymmetric system (Au + C at 1A GeV) where different
behaviours in the caloric curves are seen.


title:
Quasireal photons in nucleus-nucleus collisions at intermediate and high
  energies, applications to nuclear structure, nuclear astrophysics and
  particle physics

abstract:
  Introduction
  Theory of electromagnetic excitation and dissociation (Inelastic scattering
at high energies: one-photon exchange, semiclassical approach and Glauber
theory; Higher order electromagnetic effects, small xi-approximation)
  Discussion of experimental results for nuclear structure
  Coulomb dissociation as a tool to measure radiative capture processes
relevant to nuclear astrophysics
  Antihydrogen production and electromagnetic processes at relativistic heavy
ion colliders
  Conclusions


title:
Nucleon-nucleon bremsstrahlung: An example of the impossibility of
  measuring off-shell amplitudes

abstract:
  For nearly fifty years theoretical and experimental efforts in
nucleon-nucleon bremsstrahlung (NN$\gamma$) have been devoted to measuring
off-shell amplitudes and distinguishing among various NN potentials on the
basis of their off-shell behavior. New experiments are underway, designed
specifically to attain kinematics further off shell than in the past, and thus
to be more sensitive to the off-shell behavior. This letter shows that,
contrary to these expectations, and due to the invariance of the S-matrix under
transformations of the fields, the off-shell NN amplitude is as a matter of
principle an unmeasurable quantity in NN$\gamma$.


title: Differences between heavy and light quarks

abstract:
  The quark Dyson-Schwinger equation shows that there are distinct differences
between light and heavy quarks. The dynamical mass function of the light quarks
is characterised by a sharp increase below 1 GeV, whereas the mass function of
the heavy quarks is approximately constant in this infrared region. As a
consequence, the heavy-meson masses increase linearly with the current-quark
masses, whereas the light pseudoscalar meson masses are proportional to the
square root of the current-quark masses.


title: Leptonic and semileptonic decays of heavy mesons

abstract:
  A heavy-quark limit of the Dyson-Schwinger equations is introduced and used
in an exploratory study of leptonic and semileptonic decays of heavy mesons.
The application of this framework to heavy-to-light semileptonic decays, which
require a good knowledge of light-quark propagation characteristics and
light-meson bound state amplitudes, is illustrated.


title: Charmlets

abstract:
  We discuss the possibility, that multiply charmed exotics are produced in
ultrarelativistic heavy ion collisions. Production probabilities at RHIC are
estimated and found to be large enough to allow for the possible detection of
single and double charmed exotics. We demonstrate that charm matter is bound
due to an attractive one-gluon exchange potential. Furthermore, we study the
color magnetic and color electric potential separately, as well as the group
structure of such exotics and estimate their masses.


title: Particle Interferometry: New Theoretical Results

abstract:
  By measuring hadronic single-particle spectra and two-particle correlations
in heavy-ion collisions, the size and dynamical state of the collision fireball
at freeze-out can be reconstructed. I discuss the relevant theoretical methods
and their limitations. By applying the formalism to recent pion correlation
data from Pb+Pb collisions at CERN we demonstrate that the collision zone has
undergone strong transverse growth before freeze-out (by a factor 2-3 in each
direction), and that it expands both longitudinally and transversally. From the
thermal and flow energy density at freeze-out the energy density at the onset
of transverse expansion can be estimated from conservation laws. It comfortably
exceeds the critical value for the transition to color deconfined matter.


title:
The Rarita-Schwinger spin-3/2 equation in a nonuniform, central
  potential

abstract:
  The equations of motion for a massive spin-3/2 Rarita-Schwinger field in a
finite-range, central, Lorentz scalar potential are developed. It is shown that
the resulting density may not be everywhere positive definite.


title: Electromagnetic Corrections to the One-Pion-Exchange Potential

abstract:
  Leading-order electromagnetic loop corrections to the one-pion-exchange
potential are computed within the framework of chiral perturbation theory.
These corrections generate an effective nucleon-nucleon potential, $V_{\pi
\gamma}$, which supplements the sum of OPEP and the nucleon-nucleon Coulomb
potential. This potential is charge dependent and its construction is
demonstrated to be gauge invariant. The potential $V_{\pi \gamma}$ has been
included in the Nijmegen partial-wave analysis of np data. A particular
renormalization scheme is chosen that leads to a negligible change in the
charged-piNN coupling constant and in the np 1S0 scattering length and
effective range.


title: Can the magnetic moment contribution explain the A_y puzzle?

abstract:
  We evaluate the full one-photon-exchange Born amplitude for $Nd$ scattering.
We include the contributions due to the magnetic moment of the proton or
neutron, and the magnetic moment and quadrupole moment of the deuteron. It is
found that the inclusion of the magnetic-moment interaction in the theoretical
description of the $Nd$ scattering observables cannot resolve the long-standing
$A_y$ puzzle.


title: Deconfinement at finite chemical potential

abstract:
  In a confining, renormalisable, Dyson-Schwinger equation model of two-flavour
QCD we explore the chemical-potential dependence of the dressed-quark
propagator, which provides a means of determining the behaviour of the chiral
and deconfinement order parameters, and low-energy pion observables. We find
coincident, first order deconfinement and chiral symmetry restoration
transitions at \mu_c = 375 MeV. f_\pi is insensitive to \mu until \mu \approx
\mu_0 = 0.7 mu_c when it begins to increase rapidly. m_\pi is weakly dependent
on \mu, decreasing slowly with \mu and reaching a minimum 6% less than its
\mu=0 value at \mu=\mu_0. In a two-flavour free-quark gas at \mu=\mu_c the
baryon number density would be approximately 3 \rho_0, where \rho_0=0.16
fm^{-3}; while in such a gas at \mu_0 the density is \rho_0.


title:
Inclusive $(e,e^\prime N)$, $(e,e^\prime NN)$, $(e,e^\prime \pi)$ ...
  reactions in nuclei

abstract:
  We study the inclusive $(e,e^\prime N)$, $(e,e^\prime NN)$, $(e,e^\prime
\pi)$, $(e,e^\prime \pi N)$ reactions in nuclei using a Monte Carlo simulation
method to treat the multichannel problem of the final state. The input consists
of reaction probabilities for the different steps evaluated using microscopical
many body methods. We obtain a good agreement with experiment in some channels
where there is data and make predictions for other channels which are presently
under investigation in several electron laboratories. The comparison of the
theoretical results with experiment for several kinematical conditions and
diverse channels can serve to learn about different physical processes ocurring
in the reaction. The potential of this theoretical tool to make prospections
for possible experiments, aiming at pinning down certain reaction
probabilities, is also emphasized.


title:
Medium effects in the production and decay of vector mesons in
  pion-nucleus reactions

abstract:
  The $\omega$-, $\rho$- and $\phi$-resonance production and their dileptonic
decay in $\pi^- A$ reactions at 1.1 - 1.7 GeV/c are calculated within the
intranuclear cascade (INC) approach. The invariant mass distribution of the
dilepton pair for each resonance can be decomposed in two components which
correspond to their decay 'inside' the target nucleus and in the vacuum,
respectively. The first components are strongly distorted by the nuclear medium
due to resonance-nucleon scattering and a possible mass shift at finite baryon
density. These medium modifications are compared to background sources in the
dilepton spectrum from $\pi N$ bremsstrahlung as well as the Dalitz decays of
$\omega$ and $\eta$ mesons produced in the reaction. Detailed predictions for
$\pi^- Pb$ reactions at 1.3 and 1.7 GeV/c are made within several momentum bins
for the lepton pair.


title:
Analytical Extension of the Frazer-Fulco Unitarity Relations for
  Isovector Nucleon Form Factors to the Complex t-Plane

abstract:
  The unitarity relations for isovector nucleon form factors in the two-pion
approximation for the intermediate states are analytically extended in a model
independent way from the real half-axis t > 4 $\mu^2$ ($\mu$ is the pion mass)
to the whole complex t-plane. As a result, the explicit integral
representations for the nucleon form factors are constructed in terms of the
pion form factor and imaginary parts of the t-channel p-wave piN-scattering
amplitudes at t < 0. New method based on the explicit integral representations
is developed for numerical evaluation of the two-pion contribution to the
isovector nucleon form factors. The results of different methods are compared
and their efficiency is discussed.


title: Nucleon-Deuteron Scattering from an Effective Field Theory

abstract:
  We use an effective field theory to compute low-energy nucleon-deuteron
scattering. We obtain the quartet scattering length using low energy constants
entirely determined from low-energy nucleon-nucleon scattering. We find
$a_{th}=6.33$ fm, to be compared to $a_{exp}=6.35\pm 0.02$ fm.


title:
Can neutron electromagnetic form factors be obtained by polarized
  inclusive electron scattering off polarized three-nucleon bound states?

abstract:
  The investigation of the electromagnetic inclusive responses of polarized
$^{3}$He within the plane wave impulse approximation is briefly reported. A
particular emphasys is put on the extraction, from the inclusive responses at
the quasielastic peak, of the neutron form factors from feasible experiments.


title: First Order Phase Transition in Intermediate Energy Heavy Ion Collisions

abstract:
  We model the disassembly of an excited nuclear system formed as a result of a
heavy ion collision. We find that, as the beam energy in central collisions in
varied, the dissociating system crosses a liquid-gas coexistence curve,
resulting in a first-order phase transition. Accessible experimental signatures
are identified: a peak in specific heat, a power-law yield for composites, and
a maximum in the second moment of the yield distribution.


title:
Kaon production in heavy-ion collisions and maximum mass of neutron
  stars

abstract:
  We determine an `empirical' kaon dispersion relation by analysing and fitting
recent experimental data on kaon production in heavy-ion collisions. We then
investigate its effects on hadronic equation of state at high densities and on
neutron star properties. We find that the maximum mass of neutron stars can be
lowered by about 0.4$M_\odot$, once kaon condensation as constrained by our
empirical dispersion relation is introduced. We emphasize the growing interplay
between hadron physics, relativistic heavy-ion physics and the physics of
compact objects in astrophysics.