title:
Higher Nucleon Resonances in Exclusive $(\gamma, \pi N)$ Reactions on
  Nuclei

abstract:
  We report calculations for exclusive pion photoproduction on nuclei beyond
the first resonance region in the distorted wave impulse approximation. The
elementary operator contains contributions from the resonances $P_{33}(1232)$,
$P_{11}(1440)$, $D_{13}(1520)$, $D_{33}(1740)$, $S_{11}(1535)$, $S_{11}(1650)$,
and $F_{15}(1680)$, in addition to the usual Born plus vector meson
contributions. It gives a good description of single pion photoproduction data
up to about 1.1 GeV. Final state interactions are incorporated via optical
potentials and are found to be substantial in the coincidence cross sections,
but insensitive to the photon asymmetry. Clear signatures of possible medium
modifications of the $D_{13}$ and $F_{15}$ resonances are predicted.


title: Electromagnetic form factors of light vector mesons

abstract:
  The electromagnetic form factors G_E(q^2), G_M(q^2), and G_Q(q^2), charge
radii, magnetic and quadrupole moments, and decay widths of the light vector
mesons rho^+, K^{*+} and K^{*0} are calculated in a Lorentz-covariant,
Dyson-Schwinger equation based model using algebraic quark propagators that
incorporate confinement, asymptotic freedom, and dynamical chiral symmetry
breaking, and vector meson Bethe-Salpeter amplitudes closely related to the
pseudoscalar amplitudes obtained from phenomenological studies of pi and K
mesons. Calculated static properties of vector mesons include the charge radii
and magnetic moments: r_{rho+} = 0.61 fm, r_{K*+} = 0.54 fm, and r^2_{K*0} =
-0.048 fm^2; mu_{rho+} = 2.69, mu_{K*+} = 2.37, and mu_{K*0} = -0.40. The
calculated static limits of the rho-meson form factors are similar to those
obtained from light-front quantum mechanical calculations, but begin to differ
above q^2 = 1 GeV^2 due to the dynamical evolution of the quark propagators in
our approach.


title:
Medium Dependence of the Vector-Meson Mass: Dynamical and/or Brown-Rho
  Scaling?

abstract:
  We discuss the similarities and differences for the theories of Rapp, Wambach
and collaborators (called R/W in short) and those based on Brown-Rho scaling
(called B/R), as applied to reproduce the dileptons measured by the CERES
collaboration in the CERN experiments. In both theories the large number of
dileptons at invariant masses $\sim$~$m_\rho/2$ are shown to be chiefly
produced by a density-dependent $\rho$-meson mass. In R/W the medium dependence
is dynamically calculated using hadronic variables defined in the matter-free
vacuum. In B/R scaling it follows from movement towards chiral symmetry
restoration due to medium-induced vacuum change, and is described in terms of
constituent (or quasiparticle) quarks. We argue that the R/W description should
be reliable up to densities somewhat beyond nuclear density, where hadrons are
the effective variables. At higher density there should be a crossover to
constituent quarks as effective variables scaling according to B/R. In the
crossover region, the two descriptions must be ``dual''.


title: A Model of Charmonium Absorption by Light Mesons

abstract:
  We calculate the cross sections for dissociation of $J/\psi$ by pions and
$\rho$-mesons within the framework of a meson exchange model. We find that
these cross sections are small at center-of-mass energies less than 1 GeV above
threshold, and that dissociation rates are less than 0.01 $c$/fm in a thermal
meson gas at temperatures where such a description makes sense.


title: Are Pions Perturbative in Effective Field Theory?

abstract:
  It is shown that pions can be included perturbatively into effective field
theory only for the external momenta, well below the pion mass. But for such
low energies it is not necessary to include pions explicitly.


title: Effective Field Theories For Nuclei And Dense Matter

abstract:
  A recent development on the working of effective field theories in nuclei and
in dense hadronic matter is discussed. We consider two extreme regimes: One,
dilute regime for which fluctuations are made on top of the matter-free vacuum;
two, dense systems for which fluctuations are treated on top of the "vacuum"
defined at a given density, with masses and coupling constants varying as
function of matter density ("Brown-Rho scaling"). Based on an intricate -- as
yet mostly conjectural -- connection between the in-medium structure of chiral
Lagrangian field theory which is a beautiful effective theory of QCD and that
of Landau Fermi liquid theory which is an equally beautiful and highly
successful effective theory of many-body systems, it is suggested that a chiral
Lagrangian with Brown-Rho scaling in the mean field is equivalent to
Fermi-liquid fixed point theory. I make this connection using electroweak and
strong responses of nuclear matter up to nuclear matter density and then
extrapolating to higher densities encountered in heavy-ion collisions and
compact stars.


title: Momentum Dependence of the Pion Cloud for Rho Mesons in Nuclear Matter

abstract:
  We extend hadronic models for rho-meson propagation in cold nuclear matter
via coupling to in-medium pions to include finite three-momentum. Special care
is taken to preserve gauge invariance. Consequences for photoabsorption on the
proton and on nuclei as well as for the dilepton production in relativistic
heavy-ion collisions are discussed.


title:
Coulomb Effects on Electromagnetic Pair Production in Ultrarelativistic
  Heavy-Ion Collisions

abstract:
  We discuss the implications of the eikonal amplitude on the pair production
probability in ultrarelativistic heavy-ion transits. In this context the
Weizs\"acker-Williams method is shown to be exact in the ultrarelativistic
limit, irrespective of the produced particles' mass. A new equivalent
single-photon distribution is derived which correctly accounts for the Coulomb
distortions. As an immediate application, consequences for unitarity violation
in photo-dissociation processes in peripheral heavy-ion encounters are
discussed.


title: \bar{p}p low energy parameters from annihilation cross section data

abstract:
  The recent experimental data obtained by the OBELIX group on total $\bar{p}p$
annihilation cross section are analysed; the low energy spin averaged
parameters of the $\bar{p}p$ scattering amplitude (the imaginary parts of the
S-wave scattering length and P-wave scattering volume) are extracted from the
data. Their values are found to be equal to $Im a_{sc} = - 0.69 \pm 0.01 (stat)
\pm 0.03 (sys) fm, Im A_{sc} = - 0.76 \pm 0.05 (stat) \pm 0.04 (sys) fm^3$. The
results are in very good agreement with existing atomic data.


title:
Overbarrier Resonances as Solutions of Set Inhomogeneous Schr\"{o}dinger
  Equations

abstract:
  In the paper the Schr\"odinger equation for quasibound resonance state with
complex energy is considered. The system of inhomogeneous differential
equations is obtained for the real and imaginary parts of wave function. On the
base of known solution of corresponding homogeneous equation, the inhomogeneus
system is solved with help of iteration procedure. The single-particle neutron
$2p$-state in the Woods - Saxon potential is analyzed for $^{13}C$ nucleus.


title:
Predictions for sqrt{s} = 200 A*GeV Au+Au Collisions from Relativistic
  Hydrodynamics

abstract:
  The relativistic hydrodynamical model HYLANDER-C is used to give estimates
for single inclusive particle momentum spectra in $\sqrt{s}$ = 200
$GeV/nucleon$ Au+Au collisions that will be investigated experimentally in the
near future. The predictions are based on initial conditions that the initial
fireball has a longitudinal extension of 1.6 $fm$ and an initial energy density
of 30.8 $GeV/fm^3$ as obtained from a cascade model. For the collision energy
considered here, different stopping scenarios are explored for the first time.
Our calculations give particle yields of the order of 10,000 to 20,000 charged
particles per event.


title: Low Energy Compton Scattering and Nucleon Structure

abstract:
  The low energy virtual Compton scattering process $eN\to e'N\gamma$ offers a
new and potentially high resolution window on nucleon sturcture via measurement
of so-called generalized polarizabilities (GPs). We present calculations of GPs
within heavy baryon chiral perturbation theory and discuss present experimental
efforts.


title: Nucleon Axial Matrix Elements

abstract:
  Current issues associated with nucleon axial matrix elements are studied,
including the Goldberger-Treiman discrepancy, the induced pseudoscalar, and
SU(3) chiral perturbation theory.


title: Is SU(3) Chiral Perturbation Theory an Effective Field Theory?

abstract:
  We argue that the difficulties associated with the convergence properties of
conventional SU(3) chiral perturbation theory can be ameliorated by use of a
cutoff, which suppresses the model-dependent short distance effects in such
calculations.


title: Chiral symmetry in matter

abstract:
  Soft-pion theorems are used to show how chiral symmetry constrains the
contributions of low-momentum pions to the quark condensate, the pion decay
constant and hadron masses, all of which have been proposed as signals of
partial restoration of chiral symmetry in matter. These have contributions of
order T^2 for a pion gas or of order m_pi for cold nuclear matter, which have
different coefficients in all three cases, showing that there are no simple
relations between the changes to these quantities in matter. In particular,
such contributions are absent from the masses of vector mesons and nucleons and
so these masses cannot scale as any simple function of the quark condensate.
More generally, pieces of the quark condensate that arise from low-momentum
pions should not be associated with partial restoration of chiral symmetry.


title: Probing Chiral Symmetry Restoration with Heavy Ions

abstract:
  It is discussed how chiral symmetry restoration manifests itself through
mixing of vector and axial-vector correlators. The vector correlator is
directly accessible in relativistic heavy-ion collisions. Within models of the
vector correlator its implications for low-mass dilepton spectra are reviewed.


title:
Exploring the nuclear pion dispersion relation through the anomalous
  coupling of photon to photon and neutral pion

abstract:
  We investigate the possibility of measuring the pion dispersion relation in
nuclear matter through the anomalous coupling in the reaction \gamma - \gamma'
\pi_0. It is shown that this reaction permits the study of pionic modes for
space-like momenta. If the pion is softened in nuclear matter due to mixing
with the delta-hole state, significant strength for this reaction is expected
to move into the space-like region. Competing background processes are
evaluated, and it is concluded that useful insight can be obtained
experimentally, but only through a difficult exclusive measurement.


title: Three nucleons at very low energies

abstract:
  We discuss the effective field theory approach to nuclear phenomena with
typical momentum below the pion mass. We particularly focus on the three body
problem. In the $J=3/2$ channel,effective field theory is extremelly predictive
and we are able to describe the nucleon-deuteron scattering amplitude at the
percent level using only two parameters obtained from nucleon-nucleon
scattering. We briefly comment onthe $J=1/2$ channel and the issues related to
the non-perturbative renormalization of the three body force.


title: Wobbling motion in the multi-bands crossing region

abstract:
  The backbending in the A=180 mass region is expected to be caused by
multi-bands crossing between low-K (g- and s-bands) and high-K bands. % We
analyze a mechanism of coupling of these bands in terms of a dynamical
treatment for nuclear rotations, i.e., the wobbling motion. The wobbling states
are produced through the generator coordinate method after angular momentum
projection, in which the intrinsic states are constructed through the
2d-cranked HFB calculations.


title: Are eta- and omega-nuclear states bound ?

abstract:
  We investigate theoretically whether it is feasible to detect $\eta$- and
$\omega$-nucleus bound states. As well as the closed shell nuclei, $^{16}$O,
$^{40}$Ca, $^{90}$Zr and $^{208}$Pb, we also investigate $^6$He, $^{11}$B and
$^{26}$Mg, which are the final nuclei in the proposed experiment involving the
(d,$^3$He) reaction at GSI. Potentials for the $\eta$ and $\omega$ mesons in
these nuclei are calculated in local density approximation, embedding the
mesons in the nucleus described by solving the mean-field equations of motion
in the QMC model. Our results suggest that one should expect to find $\eta$-
and $\omega$-nucleus bound states in all these nuclei.


title: Exchange Currents in Radiative Hyperon Decays

abstract:
  A short overview of motivations and successes of two-body exchange currents
between constituent quarks for electromagnetic hadron observables like charge
radii, magnetic and quadrupole moments is given. We then predict and analyze
exchange current effects on the radiative decay widths of decuplet hyperons,
which are to be measured soon. In our chiral constituent quark model, exchange
currents dominate the E2 transition amplitude, while they largely cancel for
the M1 transition amplitude. Strangeness suppression of the radiative hyperon
decays is weakened by exchange currents. The SU(F)_3 flavor symmetry breaking
for the negatively charged hyperons is strong.


title: Forming Disoriented Chiral Condensates through Fluctuations

abstract:
  Using the influence functional formalism, classical equations of motion for
the O(N) model are derived in the presence of a heat bath, in both the
symmetric phase as well as the phase of spontaneously broken symmetry. The heat
bath leads to dissipation and fluctuation terms in the classical equations of
motion, which are explicitly computed to lowest order in perturbation theory.
In the broken phase these terms are found to be large for the sigma field, even
at zero temperature, due to the decay process sigma -> pi pi, while they are
small for the pi fields at temperatures below T_c = 160 MeV. It is shown that
in large volumes the presence of dissipation and fluctuations suppresses the
formation of disoriented chiral condensates (DCC's). In small volumes, however,
fluctuations become sufficiently large to induce the formation of DCC's even if
chiral symmetry has not been restored in the initial stage of the system's
evolution.


title:
Complete set of electromagnetic corrections to strongly interacting
  systems

abstract:
  We show how to obtain a complete set of electromagnetic corrections to a
given nonperturbative model of strong interactions based on integral equations.
The gauge invariance of these corrections is a consequence of their
completeness.


title: Nucleus-Nucleus Bremsstrahlung from Ultrarelativistic Collisions

abstract:
  The bremsstrahlung produced when heavy nuclei collide is estimated for
central collisions at the Relativistic Heavy Ion Collider. Soft photons can be
used to infer the rapidity distribution of the outgoing charge. An experimental
design is outlined.


title:
Equation of state of hadronic matter with dibaryons in an effective
  quark model

abstract:
  The equation of state of symmetric nuclear matter with the inclusion of
non-strange dibaryons is studied. We pay special attention to the existence of
a dibaryon condensate at zero temperature. These calculations have been
performed in an extended quark-meson coupling model with density-dependent
parameters, which takes into account the finite size of nucleons and dibaryons.
A first-order phase-transition to pure dibaryon matter has been found. The
corresponding critical density is strongly dependent on the value of the
dibaryon mass. The density behavior of the nucleon and dibaryon effective
masses and confining volumes have also been discussed.


title: Pion Interferometry Using Wavepackets

abstract:
  The conditions for the HBT interferometry from stars are compared to those
encountered in heavy ion reactions. As a consequence the formalism using
wavepackets is developed. The modifications relative to the standard formalism
with plane waves are presented, and the effects of the residual Coulomb
interactions between charged pions and with the charged source are calculated.


title: Multiple parton interactions in high-density QCD matter

abstract:
  Multiple interactions of quarks and gluons in high-energy heavy-ion
collisions may give rise to interesting phemomena of color charges propagating
in high-density QCD matter. We study the dynamics of multi-parton systems
produced in nucleus-nucleus collisions at energies corresponding the the CERN
SPS and the future BNL RHIC experiments. Due to the complexity of the
multi-particle dynamics we choose to employ the parton cascade model in order
to simulate the development of multiple parton scatterings and associated
stimulated emision processes. Our results indicate a non-linear increase with
nuclear mass A of, e.g., parton multiplicity, energy density, strangeness, and
contrast a linear A-scaling as in Glauber-type approaches. If multiple
interactions are suppressed and only single parton scatterings (no
re-interactions) are considered, we recover such a linear behavior. It remains
to be studied whether these results on the parton level can be experimentally
seen in final-state observables, such as the charged particle multiplicity, the
magnitude of produced transverse energy, or the number of produced strange
hadrons.


title: Meson Production and Meson Properties at Finite Nuclear Density

abstract:
  The properties of $\pi, \eta, K^+$ and $K^-$ mesons are studied in nuclear
reactions from SIS to SPS energies within the covariant transport approach HSD
in comparison to the experimental data. Whereas the pion, $\eta$ and kaon
abundancies and spectra indicate little or vanishing selfe-nergies for these
mesons in the medium, antikaons (as well as antiprotons) are found to
experience strong attractive potentials in nucleus-nucleus collisions at SIS
energies. However, even when including these potentials the $K^+$ and $K^-$
spectra at AGS energies are noticeably underestimated showing an experimental
excess of strangeness that points towards a nonhadronic phase in these
reactions. On the other hand the $K^+, K^-$ production at SPS energies is well
described by the hadronic approach without incorporating any parton degrees of
freedom.


title:
Towards the solution of the $C_{P}/C_{A}$ anomaly in shell-model
  calculations of muon capture

abstract:
  Recently many authors have performed shell-model calculations of nuclear
matrix elements determining the rates of the ordinary muon capture in light
nuclei. These calculations have employed well-tested effective interactions in
large scale shell-model studies. For one of the nuclei of interest, namely
$^{28}$Si, there exists recent experimental data which can be used to deduce
the value of the ratio $C_{P}/C_{A}$ by using the calculated matrix elements.
Surprisingly enough, all the abovementioned shell-model results suggest a very
small value ($\simeq 0$) for $C_{P}/C_{A}$, quite far from the PCAC prediction
and recent data on muon capture in hydrogen. We show that this rather
disturbing anomaly is solved by employing effective transition operators. This
finding is also very important in studies of the scalar coupling of the weak
charged current of leptons and hadrons.


title: Generalized entropy and temperature in nuclear multifragmentation

abstract:
  In the framework of a 2D Vlasov model, we study the time evolution of the
"coarse-grained" Generalized Entropy (GE) in a nuclear system which undergoes a
multifragmentation (MF) phase transition. We investigate the GE both for the
gas and the fragments (surface and bulk part respectively). We find that the
formation of the surface causes the growth of the GE during the process of
fragmentation. This quantity then characterizes the MF and confirms the crucial
role of deterministic chaos in filling the new available phase-space: at
variance with the exact time evolution, no entropy change is found when the
linear response is applied. Numerical simulations were used also to extract
information about final temperatures of the fragments. From a fitting of the
momentum distribution with a Fermi-Dirac function we extract the temperature of
the fragments at the end of the process. We calculate also the gas temperature
by averaging over the available phase space. The latter is a few times larger
than the former, indicating a gas not in equilibrium. Though the model is very
schematic, this fact seems to be very general and could explain the discrepancy
found in experimental data when using the slope of light particles spectra
instead of the double ratio of isotope yields method in order to extract the
nuclear caloric curve.

categories: nucl-th chao-dyn cond-mat.stat-mech nlin.CD nucl-ex


title: Relativity Damps OPEP in Nuclear Matter

abstract:
  Using a relativistic Dirac-Brueckner analysis the OPEP contribution to the
ground state energy of nuclear matter is studied. In the study the pion is
derivative-coupled. We find that the role of the tensor force in the saturation
mechanism is substantially reduced compared to its dominant role in a usual
nonrelativistic treatment. We show that the damping of derivative-coupled OPEP
is actually due to the decrease of $M^*/M$ with increasing density. We point
out that if derivative-coupled OPEP is the preferred form of nuclear effective
lagrangian nonrelativistic treatment of nuclear matter is in trouble. Lacking
the notion of $M^*$ it cannot replicate the damping. We suggest an examination
of the feasibility of using pseudoscalar coupled $\pi$N interaction before
reaching a final conclusion about nonrelativistic treatment of nuclear matter.


title: Lifetime of a Disoriented Chiral Condensate

abstract:
  The lifetime of a disoriented chiral condensate formed within a heat bath of
pions is calculated assuming temperatures and densities attainable at present
and future heavy-ion colliders. A generalization of the reduction formula to
include coherent states allows us to derive a formula for the decay rate. We
predict the half-life to be between 4 and 7 fm/c, depending on the assumed pion
density. We also calculate the lifetime in the presence of higher resonances
and baryons, which shortens the lifetime by at most 20%.


title:
Semiclassical Approximation to Neutron Star Superfluidity Corrected for
  Proximity Effects

abstract:
  The inner crust of a neutron star is a superfluid and inhomogeneous system,
consisting of a lattice of nuclei immersed in a sea of neutrons. We perform a
quantum calculation of the associated pairing gap and compare it to the results
one obtains in the Local Density Approximation (LDA). It is found that the LDA
overestimates the spatial dependence of the gap, and leads to a specific heat
of the system which is too large at low temperatures, as compared with the
quantal result. This is caused by the neglect of proximity effects and the
delocalized character of the single-particle wavefunctions close to the Fermi
energy. It is possible to introduce an alternative, simple semiclassical
approximation of the pairing gap which leads to a specific heat that is in good
agreement with the quantum calculation.


title: Reinvestigation of $pp\to pp\pi^0$ and $pp\to pp\eta$ at threshold

abstract:
  $pp\to pp\pi^0$ and $pp\to pp\eta$ were considered close to threshold. The
pion production was found not only to be dominated by impulse approximation
(IA) and rescattering contributions, but also strongly by box-diagrams,
resonances and heavy-meson exchanges. New relevant contributions for the IA
were found. The role of the offshell behaviour of nucleon-resonance couplings
($P_{11}(1440), S_{11}(1535)$) and of interference effects for the eta
production was investigated. The results opened a large door for microsopic
understanding of short range physics. A covariant model for $pp\to pp\eta$
being under construction is going to be finished.


title:
Bethe-Salpeter-Approach to Relativistic Two-Fermion-Systems with a
  Separable Nonstatic Interaction

abstract:
  To study the characteristic features of relativistic bound systems, the
Bethe-Salpeter equation (BSE) for two equal mass spin 1/2 particles (like the
deuteron) is solved in the cm-frame for a covariant separable interaction
kernel. For that purpose the BSE is transformed to an eigenvalue problem which
is diagonalized numerically. The Bethe--Salpeter amplitudes (BSAs) are obtained
straightforwardly from the resulting eigenvectors. Only positive parity
solutions of the eigenvalue problem are considered. To correlate the BSAs to
standard quantum mechanical wavefunctions, the corresponding
equal-time-wavefunctions (ETWs) are calculated. A decomposition of BSAs and
ETWs in partial waves in angular momenta and parity is performed. As a first
application elastic electron-deuteron-scattering in the impulse approximation
(IA) is considered. The charge, magnetic and quadrupole formfactors $F_C(k^2)$,
$F_M(k^2)$, $F_Q(k^2)$ and tensor polarizations $\tilde{t}_{20}(k^2)$, $t_{20}
(k^2,\theta_e=70^{\circ})$ are obtained from three independent matrix elements
of the deuteron current in the Breit-frame of elastic
electron-deuteron-scattering. Additionally, the formfactors $A(k^2)$ and
$B(k^2)$ of the Rosenbluth formula are calculated.


title: Proton induced $K^+$ production and the $s\bar{s}$ content of the proton

abstract:
  We investigate the exclusive proton-induced $K^+$ production near the kaon
threshold. Compared are two models: a meson-exchange model, which includes
$\pi$, \rho$, $K$ and $K^\ast$ exchange, together with the dominant baryon
resonances, and a quark-gluon model, where momentum sharing is provided via the
exchange of two gluons. Based on covariant bound state wave functions for the
meson and the baryons - which we treat as quark-diquark objects - first results
for the $pp\to p\Lambda K^+$ total cross section are presented for both models.


title:
Consistent effective field-theoretic treatment of resonances with non
  zero width

abstract:
  A systematic field theoretic formalism for treating Fermionic resonances with
non zero width is given. The implication of unitarity to coupling constants of
non local interactions is shown. The extension of the formalism to Bosonic
resonance field operators is straight forward.


title:
The pion-three-nucleon problem with two-cluster connected-kernel
  equations

abstract:
  It is found that the coupled piNNN-NNN system breaks into fragments in a
nontrivial way. Assuming the particles as distinguishable, there are indeed
four modes of fragmentation into two clusters, while in the standard three-body
problem there are three possible two-cluster partitions and conversely the
four-body problem has seven different possibilities. It is shown how to
formulate the pion-three-nucleon collision problem through the
integral-equation approach by taking into account the proper fragmentation of
the system. The final result does not depend on the assumption of separability
of the two-body t-matrices. Then, the quasiparticle method a' la
Grassberger-Sandhas is applied and effective two-cluster connected-kernel
equations are obtained. The corresponding bound-state problem is also
formulated, and the resulting homogeneous equation provides a new approach
which generalizes the commonly used techniques to describe the three-nucleon
bound-state problem, where the meson degrees of freedom are usually suppressed.


title: Density dependence of meson - nucleon vertices in nuclear matter

abstract:
  Changes in the meson-nucleon coupling constant and the vertex form factor in
nuclear matter are studied in a modified Skyrme Lagrangian including the
sigma-meson field that satisfies the scale invariance. Renormalization of the
axial-vector coupling constant, and the nucleon mass are studied in a
consistent model. The results are consistent with the empirical evidence. A
calculation of pi N commutator, sigma-term, indicates that the medium changes
its magnitude considerably.


title:
The reaction $\pi N \to \pi \pi N$ above threshold in heavy-baryon
  chiral perturbation theory

abstract:
  We study the reaction $\pi^\pm p \to \pi^\pm \pi^+ n$ and $\pi^- p \to \pi^0
\pi^0 n$ in heavy-baryon chiral perturbation theory of chiral order three from
threshold up to pion laboratory kinetic energies of 400 MeV. We find that the
contributions from amplitudes of chiral order three are large and play an
essential role in reproducing the experimental data.


title: Diquark Condensation in High Density Baryon Matter

abstract:
  We argue that cold quark matter is a color superconductor. The Cooper pairs
of QCD are spin-isospin zero, color anti-triplet diquarks. In this contribution
we review some of the available information on the quark-quark interaction in
QCD. We show that instantons provide a strongly attractive interaction in the
scalar diquark channel. In the high density phase, this interaction leads to
diquark Bose condensation with a gap on the order of 50 MeV.


title: Quark exchange and quark dynamics in diffractive electroproduction

abstract:
  A Dyson-Schwinger-based model of pomeron exchange is employed to calculate
diffractive rho-, phi- and J/psi-meson electroproduction cross sections. It is
shown that the magnitude of the current-quark mass m_f of the quark and
antiquark inside the produced vector meson determines the onset of the
asymptotic-q^2 power-law behavior of the cross section, and how correlated
quark-exchanges are included to provide a complete picture of the diffractive
electroproduction of light vector mesons applicable over all energies and
photon momenta q^2.


title:
Spinodal and dynamical instabilities at the phase transition from the
  quark-gluon plasma to hadrons

abstract:
  The stability of an expanding parton plasma is analyzed within quasi-particle
models. The effective mass of the parton is calculated self-consistently from a
gap equation which is either obtained from the Nambu Jona-Lasinio Lagrangian or
from a fit to observables calculated on the lattice. The latter shows an
effective confinement. At thermal equilibrium the stability is studied within
thermodynamics (mechanical stability) and via a linear response analysis of the
Vlasov equation. The instabilities related to a first-order phase transition
are found. For a plasma expanding in three and one dimensions far from
equilibrium a new type of instability, called dynamical, appears. The relation
to cluster formation is shown in a molecular dynamics calculation.


title:
Extrapolation of the astrophysical S factor for ^7Be(p,gamma)^8B to
  solar energies

abstract:
  We investigate the energy dependence of the astrophysical $S$ factor for the
reaction $^7$Be$(p,\gamma)^8$B, the primary source of high-energy solar
neutrinos in the solar $pp$ chain. Using simple models we explore the model
dependence in the extrapolation of the experimental data to the region of
astrophysical interest near 20 keV. We find that below approximately 400 keV
the energy dependence is very well understood and constrained by the data for
the elastic scattering of low energy neutrons from $^7$Li. Above 400 keV
nuclear distortion of the wave function of the incident proton introduces a
significant model dependence. This is particularly important for the s-wave
contribution to the $S$ factor. The extracted value of S(0) is $19.0 \pm 1.0
\pm 0.2$~eVb. The first error is experimental while the second is an estimate
of the theoretical error in the extrapolation.


title:
Kaon effective mass and energy from a novel chiral SU(3)-symmetric
  Lagrangian

abstract:
  A new chiral SU(3) Lagrangian is proposed to describe the properties of kaons
and antikaons in the nuclear medium, the ground state of dense matter and the
kaon-nuclear interactions consistently.
  The saturation properties of nuclear matter are reproduced as well as the
results of the Dirac-Br\"{u}ckner theory. Our numerical results show that the
kaon effective mass might be changed only moderately in the nuclear medium due
to the highly non-linear density effects. After taking into account the
coupling between the omega meson and the kaon, we obtain similar results for
the effective kaon and antikaon energies as calculated in the
one-boson-exchange model while in our model the parameters of the kaon-nuclear
interactions are constrained by the SU(3) chiral symmetry.


title: In-Medium $\pi-\pi$ Correlations in the '$\sigma$-Meson'-Channel

abstract:
  The present status of the in-medium invariant $\pi-\pi$ mass distribution in
the sigma-meson channel around the threshold is reviewed from the theory side
and contrasted with recent experiments on $(\pi,2\pi)$ knock-out reactions. A
preliminary investigation indicates that the strongly target-mass dependent
invariant mass enhancement of the two pions can be explained theoretically. A
more refined reaction theory is needed to confirm this result. In the
theoretical description, based on the linear sigma model, emphasis is put on
constraints from chiral symmetry.


title: Status of Effective Field Theory of NN Scattering

abstract:
  I review recent progress in developing a systematic power counting scheme for
scattering processes involving more than one nucleon.


title: Three-body decay of the d* dibaryon

abstract:
  Under certain circumstances, a three-body decay width can be approximated by
an integral involving a product of two off-shell two-body decay widths. This
``angle-average'' approximation is used to calculate the $\pi NN$ decay width
of the $d^*(J^\pi=3^+, T=0)$ dibaryon in a simple $\Delta^2$ model for the most
important Feynman diagrams describing pion emissions with baryon-baryon recoil
and meson retardation. The decay width is found to be about 0.006 (0.07, 0.5)
MeV at the $d^*$ mass of 2065 (2100, 2150) MeV for input dynamics derived from
the Full Bonn potential. The smallness of this width is qualitatively
understood as the result of the three-body decay being ``third forbidden''. The
concept of $\ell$ forbiddenness and the threshold behavior of a three-body
decay are further studied in connection with the $\pi NN$ decay of the dibaryon
$d'(J^\pi=0^-, T=0 or 2)$ where the idea of unfavorness has to be introduced.
The implications of these results are briefly discussed.


title:
Anomalous Band Structure in Odd-Odd Nuclei with the
  Quadrupole-Quadrupole Interaction

abstract:
  We perform shell model calculations in odd-odd nuclei using a
quadrupole-quadrupole interaction and single-particle splittings chosen so as
to obtain the SU(3) results. Elliott had shown that such an interaction gives
rotational bands for which the energies go as I(I+1). This is certainly true
for eve-even and for odd-even or even-odd nuclei with $K\neq 1/2$. We have
looked at odd-odd nuclei e.g $^{22}Na$ and found somewhat different behaviour.
In $^{22}Na$ the $I=1^+_1 T=0$ and $I=0^+_1 T=1$ states are degenerate, and a
rotational band built on the $I=0^+_1 T=1$ state behaves in a normal fashion.
For the $I+1^+_1 T=0$ band however, we find that the energy is given by
$E(I)-E(1^+_1)=AI(I+1)$. This differs from the `normal' behaviour which would
be $E(I)-E(1^+_1)=AI(I+1)-2A$.


title:
Description of even-even triaxial Nuclei within the Coherent State and
  the Triaxial Rotation-Vibration Models

abstract:
  The coherent state model (CSM) and the triaxial rotation-vibration model
(TRVM) are alternatively used to describe the ground, gamma and beta bands of
228Th. CSM is also applied to the nuclei 126Xe and 130Ba, which were recently
considered in TRVM. The two models are compared with respect to both their
underlying assumptions and to their predicted results for energy levels and E2
branching ratios. Both models describe energies and quadrupole transitions of
228Th equally well and in good agreement with experiment, if the 0$_3^+$ level
at 1120 keV is interpreted as the head of the beta band. The other two 0$^+$
levels at 832 and 939 keV are most likely not of a pure quadrupole vibration
nature as has already been pointed out in the literature.


title: R-matrix and K-matrix analysis of elastic alpha-alpha scattering

abstract:
  The R- and K-matrix parametrizations are analyzed and compared for the
elastic alpha-alpha scattering at center-of-mass energies below 40 MeV. The two
parametrizations differ in their definitions of the resonance energy which can
lead to quite different results. The physical values of the best-fit parameters
are compared with those computed for a potential model. The existence of a
broad resonance near 9 MeV is not supported by the data or by the potential
model. We discuss the positive and negative aspects for both parametrizations.


title: Saturnalia

abstract:
  A personal choice is made of the highlights of the physics programme carried
out at the Saturne-2 facility over the last twenty years.


title: Saturnales

abstract:
  Un choix personnel a ete fait d'evenements memorables du programme de
physique realise a Saturne-2 pendant les derniers 20 ans.


title: The elementary p(p,p'\pi^{+})n reaction

abstract:
  A detailed study of the elementary p(p,p$'\pi^{+}$)n reaction is presented
using the delta isobar model. In this model, in the first step one of the two
protons in the initial state gets excited to $\Delta $. This, in the second
step, decays into a nucleon and a pion. For the $pp \to N\Delta$ step the
parametrized form of the DWBA t-matrix of Jain and Santra, which reproduces
most of the available data on $pp \to n\Delta^{++}$, is used. The
cross-sections studied include the outgoing proton momentum spectra in
coincidence with the pion, the outgoing pion momentum spectra and the
integrated total cross-section. We find that all the calculated numbers are in
good agreement with the corresponding measured cross sections.


title:
Vector mesons in nuclear medium with small three momentum, a QCD sum
  rule approach

abstract:
  Using the QCD Operator Product Expansion, we derive the real part of the
transverse and longitudinal vector vector correlation function with the
$\rho,\omega$ quantum numbers to leading order in density and in ${\bf q}^2$ at
$-\omega^2\to \infty $. To dimension 6, only twist-2 and 4 operators
contribute. These OPE, through the energy dispersion relation, provide model
independent constraints for the ${\bf q}$ dependence of the vector meson
spectral density in nuclear medium. We further make a QCD sum rule type of
analysis to extract the momentum dependence of the vector meson dispersion
relation in medium. The contributions from twist-2 operators are added up to
infinite order to check the validity of the OPE at the relevant Borel window.


title:
Parity-Violating $\Delta$(1232) Electroweak Production: Axial Structure
  and New Physics

abstract:
  We consider prospects for studying the parity-violating electroweak
excitation of the $\Delta (1232) $ resonance with polarized electron scattering
(see nucl-th/9801025). We discuss the experimental feasibility and theoretical
interpretability of such a measurement as well as the prospective implications
for hadron structure theory. We also analyze the extent to which a PV
$N\to\Delta$ measurement could constrain various extensions of the Standard
Model.


title: The Polarizability of the Deuteron

abstract:
  The scalar and tensor polarizabilities of the deuteron are calculated using
the recently developed effective field theory that describes nucleon-nucleon
interactions. Leading and next-to-leading order contributions in the
perturbative expansion predict a scalar electric polarizability of 0.595 fm^3.
The tensor electric polarizability receives contributions starting at
next-to-leading order from the exchange of a single potential pion and is found
to be -0.062 fm^3. We compute the leading contributions to the scalar and
tensor magnetic polarizabilities, finding 0.067 fm^3 and 0.195 fm^3,
respectively.


title: Solar Neutrino Interactions with 18O in SuperKamiokande

abstract:
  The ratio of 18O nuclei to electrons in SuperKamiokande is quite small, about
1:5000. However this nucleus provides two unpaired neutrons and a low threshold
for solar neutrino absorption, resulting in an unusually large cross section.
The 18O nuclei, together with 17O and deuterium, will produce in excess of 460
scattered electrons per year with energies above the initial SuperKamiokande
threshold of 6.5 MeV, or about 6.7% of the total solar neutrino signal, for an
electron neutrino flux scaled to the current SuperKamiokande counting rate. We
explore whether this might complicate efforts to extract the neutrino spectrum
from elastic scattering events and whether there might be any prospect of
combining 18O and elastic scattering events to separate charged and neutral
current interactions. Under current operating conditions the answers are no, as
the Fermi, Gamow Teller, and forbidden contributions to the 18O cross section
conspire to produce a nearly isotropic cross section. Thus most of the events
are indistinguishable from background. This result is relevant to
SuperKamiokande detection of solar antineutrinos, which arise in certain
oscillation scenarios.


title:
Half-lives and pre-supernova weak interaction rates for nuclei away from
  the stability line

abstract:
  A detailed model for the calculation of beta decay rates of the $fp$ shell
nuclei for situations prevailing in pre-supernova and collapse phases of
evolution of the core of massive stars leading to supernova explosion has been
extended for electron-capture rates. It can also be used to determine the
half-lives of neutron-rich nuclei in the $fp/fpg$ shell. The model uses an
averaged Gamow-Teller (GT) strength function. But it can also use the
experimental log ft values and GT strength function from $(n,p)$ reaction
studies wherever available. The calculated rate includes contributions from
each of the low-lying excited states of the mother including some specific
resonant states ("back resonance") having large GT matrix elements.


title:
Mean Field Methods for Atomic and Nuclear Reactions: The Link between
  Time--Dependent and Time--Independent Approaches

abstract:
  Three variants of mean field methods for atomic and nuclear reactions are
compared with respect to both conception and applicability: The time--dependent
Hartree--Fock method solves the equation of motion for a Hermitian density
operator as initial value problem, with the colliding fragments in a continuum
state of relative motion. With no specification of the final state, the method
is restricted to inclusive reactions. The time--dependent mean field method, as
developed by Kerman, Levit and Negele as well as by Reinhardt, calculates the
density for specific transitions and thus applies to exclusive reactions. It
uses the Hubbard--Stratonovich transformation to express the full
time--development operator with two--body interactions as functional integral
over one--body densities. In stationary phase approximation and with Slater
determinants as initial and final states, it defines non--Hermitian,
time--dependent mean field equations to be solved self--consistently as
boundary value problem in time. The time--independent mean field method of
Giraud and Nagarajan is based on a Schwinger--type variational principle for
the resolvent. It leads to a set of inhomogeneous, non--Hermitian equations of
Hartree--Fock type to be solved for given total energy. All information about
initial and final channels is contained in the inhomogeneities, hence the
method is designed for exclusive reactions. A direct link is established
between the time--dependent and time--independent versions. Their relation is
non--trivial due to the non--linear nature of mean field methods.


title:
Self-consistent collective subspaces and diabatic/adiabatic motion in
  nuclei

abstract:
  We discuss the application of a theory of large-amplitude collective motion
to a simple model mimicking the pairing-plus-quadrupole model of nuclear
physics.


title:
Microscopic calculation of transition intensities for vibrational bands
  and high-K isomers

abstract:
  We investigate the effect of the Coriolis coupling and the residual
interactions upon the inter-band transition rates for the vibrational bands and
the decay of two-quasiparticle high-K isomers.


title: Chiral Symmetry Restoration and Pion Interaction in Nuclear Matter

abstract:
  This paper is devoted to the interplay between p-wave, s-wave pion-nucleon/
nucleus interaction and in-medium pion-pion interaction with special emphasis
on the role of the nuclear pionic scalar density driving a large amount of
chiral symmetry restoration. In particular we show that the $\pi NN$ coupling
constant and the Goldberger-Treiman relation are preserved in the nuclear
medium within certain conditions. We also discuss the related problem of the
in-medium pion-pion strength function.


title: Nuclei in a chiral SU(3) model

abstract:
  Nuclei can be described satisfactorily in a nonlinear chiral SU(3)-framework,
even with standard potentials of the linear $\sigma$-model. The condensate
value of the strange scalar meson is found to be important for the properties
of nuclei even without adding hyperons. By neglecting terms which couple the
strange to the nonstrange condensate one can reduce the model to a Walecka
model structure embedded in SU(3). We discuss inherent problems with chiral
SU(3) models regarding hyperon optical potentials.


title: Nonperturbative effects in QCD at Finite Temperature and Density

abstract:
  These lecture notes illustrate the application of Dyson-Schwinger equations
in QCD. The extensive body of work at zero temperature and chemical potential
is represented by a selection of contemporary studies that focus on solving the
Bethe-Salpeter equation, deriving an exact mass formula in QCD that describes
light and heavy pseudoscalar mesons simultaneously, and the calculation of the
electromagnetic pion form factor and the vector meson electroproduction cross
sections. These applications emphasise the qualitative importance of the
momentum-dependent dressing of elementary Schwinger functions in QCD, which
provides a unifying connection between disparate phenomena. They provide a
solid foundation for an extension of the approach to nonzero temperature and
chemical potential. The essential, formal elements of this application are
described and four contemporary studies employed to exemplify the method and
its efficacy. They study the demarcation of the phase boundary for
deconfinement and chiral symmetry restoration, the calculation of bulk
thermodynamic properties of the quark-gluon plasma and the response of pi- and
rho-meson observables to T and mu. Along the way a continuum order parameter
for deconfinement is introduced, an anticorrelation between the response of
masses and decay constants to T and their response to mu elucidated, and a
(T,mu)-mirroring of the slow approach of bulk thermodynamic quantities to their
ultrarelativistic limit highlighted. These effects too are tied to the
momentum-dependent dressing of the elementary Schwinger functions.


title:
Transverse momentum and energy correlations in the equilibrium system
  from high-energy nuclear collisions

abstract:
  The so-called $\Phi$ parameter, which measures the transverse momentum or
energy correlations (fluctuations) in high-energy collisions independently of
the particle multiplicity, is computed for the equilibrium ideal gas. As
expected $\Phi$ vanishes for the particles obeying Boltzmann statistics but is
finite for the quantum particles, positive for bosons and negative for
fermions. $\Phi_{p_{\perp}}$, which is found for the pions gas, significantly
exceeds the value of $\Phi_{p_{\perp}}$ measured by the NA49 experiment. The
discrepancy is discussed.


title: Double Pion Production Reactions

abstract:
  We report on reactions producing two pions induced by real and virtual
photons or nucleons. The role of different resonances in these reactions is
emphasized. Novel results on coherent two pion photoproduction in nuclei are
also reported.


title:
On the Approximation in the Hermitian Treatment of Dyson Boson Expansion
  Theory

abstract:
  We discuss about the Hermitian treatment of Dyson-type boson expansion
theory. We show that the basic assumption of the conventional treatment does
not hold in general and the method is only approximately valid. We also show
that the approximation is the same order as that of truncation of the expansion
usually done in the Hermitian type boson expansion theory.


title: Band Crossing studied by GCM with 3D-CHFB

abstract:
  We solved the constrained Hill-Wheeler Equation, and found several signatures
of multi-band crossing in 182 Os.


title:
Nucleon-nucleon effective potential in dense matter including rho-meson
  exchange

abstract:
  We obtain the RPA summed one-meson exchange potential between nucleons in
symmetric nuclear matter at zero temperature, from a model which includes $\rho
$, $\sigma $, $\omega $ and $\pi $ mesons. The behavior of rho mesons inside
the medium is first discussed using different schemes to extract a finite
contribution from the vacuum polarization. These schemes give qualitatively
different results for the in-medium rho mass. The results are discussed in
connection with the non-renormalizability of the model. We next study the
modified potential as density increases. In the intermediate distance range, it
is qualitatively modified by matter and vacuum effects. In the long-distance
range ($r>2$ fm), one observes the presence of oscillations, which are not
present in free-space. Features on this distance range are insensitive to the
renormalization scheme.


title: Rotational alignment near N=Z and proton-neutron correlations

abstract:
  The effects of the residual proton-neutron interactions on bandcrossing
features are studied by means of shell model calculations for nucleons in a
high-j intruder orbital. The presence of an odd-nucleon shifts the frequency of
the alignment of two nucleons of the other kind along the axis of rotation. It
is shown that the anomalous delayed crossing observed in nuclei with aligning
neutrons and protons occupying the same intruder subshell can be partly
attributed to these residual interactions.


title: Relativistic Equation of State of Nuclear Matter for Supernova Explosion

abstract:
  We construct the equation of state (EOS) of nuclear matter at finite
temperature and density with various proton fractions within the relativistic
mean field (RMF) theory for the use in the supernova simulations. The
Thomas-Fermi approximation is adopted to describe the non-uniform matter where
we consider nucleus, alpha-particle, proton and neutron in equilibrium. We
treat the uniform matter and non-uniform matter consistently using the RMF
theory. We tabulate the outcome as the pressure, free energy, entropy etc, with
enough mesh points in wide ranges of the temperature, proton fraction, and
baryon mass density.


title: Nucleon Polarizibilities for Virtual Photons

abstract:
  We generalize the sum rules for the nucleon electric plus magnetic
polarizability $\Sigma=\alpha+\beta$ and for the nucleon spin-polarizability
$\gamma$, to virtual photons with $Q^2>0$. The dominant low energy cross
sections are represented in our calculation by one-pion-loop graphs of
relativistic baryon chiral perturbation theory and the $\Delta(1232)$-resonance
excitation. For the proton we find good agreement of the calculated
$\Sigma_p(Q^2)$ with empirical values obtained from integrating up
electroproduction data for $Q^2<0.4 GeV^2$. The proton spin-polarizability
$\gamma_p(Q^2)$ switches sign around $Q^2= 0.4 GeV^2$ and it joins smoothly the
"partonic" curve, extracted from polarized deep-inelastic scattering, around
$Q^2=0.7 GeV^2$. For the neutron our predictions of $\Sigma_n(Q^2)$ and
$\gamma_n(Q^2)$ agree reasonably well at $Q^2=0$ with existing determinations.
Upcoming (polarized) electroproduction experiments will be able to test the
generalized polarizability sum rules investigated here.


title:
3P_2-3F_2 pairing in neutron matter with modern nucleon-nucleon
  potentials

abstract:
  We present results for the $^3P_2 - ^3F_2$ pairing gap in neutron matter with
several realistic nucleon-nucleon potentials, in particular with recent,
phase-shift equivalent potentials. We find that their predictions for the gap
cannot be trusted at densities above $\rho\approx 1.7\rho_0$, where $\rho_0$ is
the saturation density for symmetric nuclear matter. In order to make
predictions above that density, potential models which fit the nucleon-nucleon
phase shifts up to about 1 GeV are required.


title: Parameter Symmetry of the Interacting Boson Model

abstract:
  We discuss the symmetry of the parameter space of the interacting boson model
(IBM). It is shown that for any set of the IBM Hamiltonian parameters (with the
only exception of the U(5) dynamical symmetry limit) one can always find
another set that generates the equivalent spectrum. We discuss the origin of
the symmetry and its relevance for physical applications.


title: Soft Neutron Production in DIS: a Window to the Final State Interactions

abstract:
  Recently E-665 reported the first measurement of soft ($E_n \le 10 $MeV)
neutron production in deep inelastic scattering (DIS) off nuclei. We report the
first theoretical analysis of the data. We find that the observed cross section
can be quantitatively explained as due to the final state interactions (FSI) of
low energy nucleons ($E_N \sim 200-400 MeV$) produced in the elementary $\mu N$
interactions. We argue that the data indicate strong a suppression of the FSI's
of fast partons (hadrons) in DIS at high energies, and that studies of the soft
neutron production would provide a new sensitive probe of the dynamics of FSI's
in DIS both at fixed target energies and at the HERA $eA$ collider.


title:
Vector Meson Photoproduction with an Effective Lagrangian in the Quark
  Model

abstract:
  A quark model approach to the photoproduction of vector mesons off nucleons
is proposed. Its starting point is an effective Lagrangian of the interaction
between the vector meson and the quarks inside the baryon, which generates the
non-diffractive s- and u- channel resonance contributions. Additional t-channel
$\pi^0$ and $\sigma$ exchanges are included for the $\omega$ and $\rho^0$
production respectively to account for the large diffractive behavior in the
small $t$ region as suggested by Friman and Soyeur. The numerical results are
presented for the $\omega$ and $\rho$ productions in four isospin channels with
the same set of parameters, and they are in good agreement with the available
data not only in $\omega$ and $\rho^0$ productions but also in the charged
$\rho$ productions where the additional t-channel $\sigma$ exchange does not
contribute so that it provides an important test to this approach. The
investigation is also extended to the $\phi$ photoproduction, and the initial
results show that the non-diffractive behavior of the $\phi$ productions in the
large $t$ region can be described by the s- and u- channel contributions with
significantly smaller coupling constants, which is consistent with the findings
in the similar studies in the QHD framework. The numerical investigation has
also shown that polarization observables are essential for identifying
so-called "missing resonances".


title:
Realistic Effective Interactions and Large-Scale Nuclear Structure
  Calculation

abstract:
  We describe the properties of complex nuclei, such as the Sn isotopes with
mass numbers A = 100 - 132, in terms of the free nucleon--nucleon interaction
as obtained from meson--exchange theory. This amounts to first calculating an
effective interaction in which the free interaction is modified by the presence
of the appropriate nuclear medium. The short--range correlations are included
within the framework of Brueckner theory yielding the nuclear reaction matrix
and the long--range correlations by using the reaction matrix in many--body
perturbation theory to obtain an effective interaction. The resulting effective
interaction is then employed in calculating the nuclear properties. Particular
emphasis is placed on the ability of our calculation to describe systematic
trends of the properties of these nuclei. Both successful achievements and
problematic features are pointed out.


title:
VNI-4.1: Simulation of space-time evolution of e^+e^- .... A+B
  collisions with parton-cascades, parton-hadron conversion, final-state hadron
  cascades

abstract:
  VNI is a general-purpose Monte-Carlo event-generator, which includes the
simulation of lepton-lepton, lepton-hadron, lepton-nucleus, hadron-hadron,
hadron-nucleus, and nucleus-nucleus collisions. It uses the real-time evolution
of parton cascades in conjunction with a self-consistent hadronization scheme,
as well as the development of hadron cascades after hadronization. The causal
evolution from a specific initial state (determined by the colliding beam
particles) is followed by the time-development of the phase-space densities of
partons, pre-hadronic parton clusters, and final-state hadrons, in
position-space, momentum-space and color-space. The parton-evolution is
described in terms of a space-time generalization of the familiar
momentum-space description of multiple (semi)hard interactions in QCD,
involving 2 -> 2 parton collisions, 2 -> 1 parton fusion processes, and 1 -> 2
radiation processes. The formation of color-singlet pre-hadronic clusters and
their decays into hadrons, on the other hand, is treated by using a spatial
criterion motivated by confinement and a non-perturbative model for
hadronization. Finally, the cascading of produced pre-hadronic clusters and of
hadrons is includes a multitude of 2 -> n processes, and is modeled in paralell
to the parton cascade description. This paper gives a brief review of the
physics underlying VNI, as well as a detailed description of the program
itself. The latter program description emphasizes easy-to-use pragmatism and
explains how to use the program (including simple examples), annotates input
and control parameters, and discusses output data provided by it.


title:
Partially conserved axial current constraints on pion
  production/absorption within nonrelativistic dynamics

abstract:
  We show the necessity of two-nucleon axial currents and associated pion
emission/ absorption operators for the partial conservation of the axial
current (PCAC) nuclear matrix elements with arbitrary nuclear dynamics
described by a nonrelativistic Schroedinger equation. As examples we construct
such nonrelativistic axial two-body currents in the linear- and heterotic (g_A
= 1.26) sigma models, with an optional isoscalar vector (omega) meson exchange.
The nuclear matrix elements obey PCAC only if the nuclear wave functions used
in the calculation are solutions to the Schroedinger equation with the static
one-meson-exchange potential constructed in the respective (sigma) model. The
same holds true for the nucler pion production amplitude, since it is
proportional to the divergence of the axial current matrix element, by virtue
of PCAC. Thus we found a new consistency condition between the pion
creation/absorption operator and the nuclear Hamiltonian. We present examples
drawn from our models and discuss implications for one-pion-two-nucleon
processes.


title: Flavor Asymmetry in Hyperons and Drell-Yan Processes

abstract:
  SU(3), baryon octets and a meson cloud model are compared for the flavor
asymmetry of sea quarks in the $\Sigma^+$, as an example. Large differences are
found, especially between SU(3) and the meson cloud model. We suggest Drell-Yan
measurements of $\Sigma^{+}-p$ and $\Sigma^{+}- d$ to test the prediction of
various models. We use the meson cloud model to predict both valence and sea
quark distributions.


title:
A unitary isobar model for pion photo- and electroproduction on the
  proton up to 1 GeV

abstract:
  A new operator for pion photo- and electroproduction has been developed for
nuclear applications at photon equivalent energies up to 1 GeV. The model
contains Born terms, vector mesons and nucleon resonances ($P_{33}(1232)$,
$P_{11}(1440)$, $D_{13}(1520)$, $S_{11}(1535)$, $F_{15}(1680)$, and
$D_{33}(1700)$). The resonance contributions are included taking into account
unitarity to provide the correct phases of the pion photoproduction multipoles.
The $Q^2$ dependence of electromagnetic resonance vertices is described with
appropriate form factors in the electromagnetic helicity amplitudes. Within
this model we have obtained good agreement with the experimental data for pion
photo- and electroproduction on the nucleon for both differential cross
sections and polarization observables. The model can be used as a starting
point to predict and analyze forthcoming data.


title:
Coherent Photoproduction of Eta-Mesons on Spin-Zero Nuclei in a
  Relativistic, Non-local Model

abstract:
  The coherent photoproduction of $\eta$-mesons on spin-zero nuclei is studied
in a relativistic, non-local model, which we have previously applied to the
coherent photoproduction of pions. We find that different off-shell
extrapolations of the elementary production operator lead to large effects in
the cross section. We also show that the almost complete suppression of the
N(1535) seen in earlier studies on this reaction is a result of the local or
factorization approximation used in these works. Non-local effects can lead to
a considerable contribution from this resonance. The relative size of the
N(1535) contribution depends on the structure of the nucleus under
consideration. We give an estimate for the contribution of the N(1520)
resonance and discuss the effect of an $\eta$-nucleus optical potential


title:
Extraction of Electrostrong Parameters of $N^{*}(1520)$ from Eta
  Photoproduction

abstract:
  Recently obtained polarized target and photon asymmetry data in eta
photoproduction are shown to be very powerful, in conjunction with the
differential cross-section data, in yielding model-insensitive constraints on
the electrostrong parameters for the excitation and decay of the $N^{*}(1520)$
resonance. The extracted ratio of its electromagnetic helicity amplitudes,
$A_{3/2}/A_{1/2}$, provides a critical test for the QCD-inspired hadron models.


title:
Spectral Distribution Studies with Modified Kuo-Brown Interaction in the
  Upper Half of the fp Shell

abstract:
  The spectral distribution method with modified Kuo-Brown interaction is
extended to the study of the upper half as well as to odd-A nuclei, of the fp
shell. The calculations show similar success to that obtained for the lower
half.


title:
Intermediate-mass dilepton spectra and the role of secondary hadronic
  processes in heavy-ion collisions

abstract:
  We carry out a study of intermediate-mass (between 1 and 2.5 GeV) dilepton
spectra from hadronic interactions in heavy-ion collisions. The processes
considered are $\pi\pi\to l{\bar l}$, $\pi\rho\to l{\bar l}$, $\pi a_1\to
l{\bar l}$, $\pi\omega\to l{\bar l}$, $K{\bar K}\to l{\bar l}$, and $K{\bar
K^*}+c.c \to l{\bar l}$. The elementary cross sections for those are obtained
from chiral Lagrangians involving pseudoscalar, vector, and axial-vector
mesons. The respective electromagnetic form factors are determined by fitting
to experimental data for the reverse processes of $e^+e^-\to hadrons$. Based on
this input we calculate cross sections and thermal dilepton emission rates and
compare our results with those from other approaches. Finally we use these
elementary cross sections with a relativistic transport model and calculate
dilepton spectra in S+W collisions at SPS energies. The comparison of our
results with experimental data from the HELIOS-3 collaboration indicates the
importance of the secondary hadronic contributions to the intermediate-mass
dilepton spectra.


title: Some exact solutions of reduced scalar Yukawa theory

abstract:
  The scalar Yukawa model, in which a complex scalar field interact via a real
scalar field, is reduced by using covariant Green functions. It is shown that
exact few-particle eigenstates of the truncated QFT Hamiltonian can be obtained
in the Feshbach-Villars formulation if an unorthodox "empty" vacuum state is
used. Analytic solutions for the two-body case are obtained for massless chion
exchange in 3+1 dimensions and for massive chion exchange in 1+1 dimensions.
Comparison is made to ladder Bethe-Salpeter, Feynman-Schwinger and
quasipotential results for massive chion exchange in 3+1. Equations for the
three-body case are also obtained.


title: S_eff(E) and the 7Be(p,gamma)8B reaction

abstract:
  We explore approximations to the effective $S$ factor for the
$^7Be(p,\gamma)^8B$ reaction using different approximation for the integral
over the Gamov peak. In the temperature range of interest for solar neutrino
production, $S_{eff}(E)$ may be determined to within 0.5% from S(20) with no
direct information on the derivatives of S(E).


title:
Deconfinement and Hadron Properties at Extremes of Temperature and
  Density

abstract:
  After introducing essential, qualitative concepts and results, we discuss the
application of Dyson-Schwinger equations to QCD at finite T and mu. We
summarise the calculation of the critical exponents of two-light-flavour QCD
using the chiral and thermal susceptibilities; and an algebraic model that
elucidates the origin of an anticorrelation between the mu- and T-dependence of
a range of meson properties. That model also provides an algebraic
understanding of why the finite-T behaviour of bulk thermodynamic properties is
mirrored in their mu-dependence, and why meson masses decrease with mu even
though f_pi and -<q-bar q> increase. The possibility of diquark condensation is
canvassed. Its realisation is uncertain because it is contingent upon an
assumption about the quark-quark scattering kernel that is demonstrably false
in some applications; e.g., it predicts the existence of coloured diquarks in
the strong interaction spectrum, which are not observed.


title: The energies and residues of the nucleon resonances N(1535) and N(1650)

abstract:
  We extract pole positions for the N(1535) and N(1650) resonances using two
different models. The positions are determined from fits to different subsets
of the existing $\pi N\to\pi N$, $\pi N\to\eta N$ and $\gamma p\to\eta p$ data
and found to be 1515(10)--i85(15)MeV and 1660(10)--i65(10)MeV, when the data is
described in terms of two poles. Sensitivity to the choice of fitted data is
explored. The corresponding $\pi \pi$ and $\eta \eta$ residues of these poles
are also extracted.


title: The 3-flavor A-scaled Nambu-Jona-Lasinio model

abstract:
  We review the so called A-scaled Nambu-Jona-Lasinio model both in the vacuum
and at finite temperature and density in the case of three flavors. Starting
from QCD and integrating out the gluons, we show how to reintroduce some of
their effects in order to take into account the trace (or scale) anomaly of
QCD. The axial U_A(1) anomaly is also present in the model in order to discuss
the eta' particle. In the present work we treat the pseudoscalar and scalar
sectors, pointing out the defects related to the omission of the vector
particles. We use our model to study the restoration of chiral symmetry as a
function of temperature, the thermodynamical functions and the equation of
state, and we survey the mixing between the scalar isoscalar particles and the
glueball.


title: Relativistic Quark Physics

abstract:
  We present a brief survey of the development of nuclear physics towards
relativistic quark physics. This is followed by a thorough discussion of the
quest for the observation of the dissolution of nuclear matter into the
deconfined quark matter (QGP) in relativistic nuclear collisions. Use of
strange particle signatures in search for QGP is emphasized.


title:
Scaling Properties of the Giant Dipole Resonance Width in Hot Rotating
  nuclei

abstract:
  We study the systematics of the giant dipole resonance width $\Gamma$ in hot
rotating nuclei as a function of temperature $T$, spin $J$ and mass $A$. We
compare available experimental results with theoretical calculations that
include thermal shape fluctuations in nuclei ranging from A=45 to A=208. Using
the appropriate scaled variables, we find a simple phenomenological function
$\Gamma(A,T,J)$ which approximates the global behavior of the giant dipole
resonance width in the liquid drop model. We reanalyze recent experimental and
theoretical results for the resonance width in Sn isotopes and $^{208}$Pb.


title: Bremsstrahlung Dileptons in Ultra-relativistic Heavy Ion Collisions

abstract:
  We consider production of dilepton pairs through coherent electro-magnetic
radiation during nuclear collisions. We show that the number of pairs produced
through bremsstrahlung is about two orders of magnitude smaller than the yield
measured by the CERES collaboration. Therefore, coherent bremsstrahlung can be
ruled out as an explanation for the observed enhancement of low mass dileptons
in CERES and HELIOS.


title:
Parity Violation in Effective Field Theory and the Deuteron Anapole
  Moment

abstract:
  Effective field theory, including pions, provides a consistent and systematic
description of nucleon-nucleon strong interactions up to center-of-mass
momentum of order 300 MeV per nucleon. We describe the inclusion of hadronic
parity violation into this effective field theory and find an analytic form for
the deuteron anapole moment at leading order in the expansion.


title:
Shadowing and Antishadowing Effects in a Model for the n+d Total Cross
  Section

abstract:
  Based on the multiple scattering series incorporated in the Faddeev scheme
the high energy limit of the total n+d cross section is evaluated in a
nonrelativistic model system where spins are neglected. In contrast to the
naive expectation that the total n+d scattering cross section is the sum of two
NN cross sections we find two additional effects resulting from rescattering
processes. These additional terms have different signs (shadowing and
antishadowing) and a different behavior as function of the energy. Our
derivation of these results which are already known from Glauber theory is
based on the analytical evaluation of elastic transition amplitudes in the high
energy limit. It does not depend on the diffraction type assumptions connected
with Glauber theory. In this model of spinless Yukawa type forces (with no
absorption) the total n+d cross section does not approach twice the NN total
cross section in the high energy limit but rather approaches the total NN cross
section multiplied by a number larger than two. Therefore, the enhancement
effect resulting from rescattering is larger than the shadowing effect, which
decreases faster with energy.


title: On the three-body continuum spectrum of He-6

abstract:
  In recent publications Cobis, Fedorov, and Jensen claim the existence of
several previously unknown low-lying narrow resonances in He-6. I show that the
distribution of the S-matrix poles corresponding to these states is unphysical.
This casts doubt on the results of those works concerning resonances.


title: Electromagnetic Processes in Three-Nucleon Systems

abstract:
  Results gained for electron scattering on $^3$He in a nonrelativistic
framework are reviewed. The electromagnetic current is truncated to a single
nucleon operator, but the interaction among the three nucleons is treated
exactly. Thus initial and final 3N states are evaluated consistently as
solutions of Faddeev equations based on realistic NN forces. The correct
inclusion of the final state interaction turned out to be important. The
agreement to data is reasonably good, but the neglection of MEC's can be seen.
That inconsistency should be removed. For pd capture processes we included some
MEC's via the Siegert theorem, which dramatically improves the description of
the pd capture data.


title: Weak Decay of Lambda Hypernuclei

abstract:
  We review recent developments concerning the weak decay of Lambda
hypernuclei. New studies covering the mesonic decay channel as well as recent
models for the non-mesonic one are discussed and compared with experimental
data. The puzzle of the neutron- to proton-induced decay ratio,
Gamma_n/Gamma_p, is addressed in connection to the two-nucleon induced decay
channel and proposals for more efficient experimental analyses of this ratio
are made.


title:
Coherent and Non-Coherent Double Diffractive Production of $ Q \bar {Q}
  $ - pairs in Collisions of Heavy Ions at High Energies

abstract:
  The double coherent and non-coherent diffractive production of heavy quark -
antiquark pairs ($Q \bar{Q}$) in heavy ion scattering at high energies (LHC) is
considered. The total and differential cross sections of these processes with
the formation of $c \bar{c}$ and $b \bar{b}$ pairs in $pp$, $CaCa$ and $PbPb$
collisions are evaluated. The contribution of the considered mechanisms is a
few per cent of the number of heavy quark - antiquark pairs obtained in the
processes of hard (QCD) scattering, and it will be taken into account in the
registration of $c$, $b$ quarks or, for instance, in the study of the heavy
quarkonia suppression effects in Quark - Gluon Plasma, in the search for
intermediate mass Higgs bosons and so on. It is shown that the cross section of
the coherent scattering process is great enough. This makes it suitable for
studying collective effects in nuclear interactions at high energies. An
example of such effects is given: large values of the invariant mass of a $Q
\bar{Q}$pair, $M_{Q \bar{Q}} \gsim 100$ GeV, in association with a large
rapidity gap between diffractive jets $\Delta \eta > 5$.


title: On quasi-bound states in eta-nucleys systems

abstract:
  The optical potential for the $\eta$-meson is calculated. This is based on a
new determination of a large $\eta$-N scattering length and recent experiments
of $\eta$ production in two nucleon collisions. These determine the $\eta$ -
nuclear potential well to be about 45 MeV deep and able to support S, P, D and
F quasibound states. Some of the higher angular momentum states are fairly
narrow and offer a chance of experimental detection.


title: Event Anisotropy in High Energy Nucleus-Nucleus Collisions

abstract:
  The predictions of event anisotropy parameters from transport model RQMD are
compared with the recent experimental measurements for 158$A$ GeV Pb+Pb
collisions. Using the same model, we study the time evolution of event
anisotropy at 2$A$ GeV and 158$A$ GeV for several colliding systems. For the
first time, both momentum and configuration space information are studied using
the Fourier analysis of the azimuthal angular distribution. We find that, in
the model, the initial geometry of the collision plays a dominant role in
determining the anisotropy parameters.


title:
Comparison of Regularization Methods for Nucleon-Nucleon Effective Field
  Theory

abstract:
  The characteristics of a meaningful effective field theory (EFT) analysis are
discussed and compared with traditional approaches to NN scattering. A key
feature of an EFT treatment is a systematic expansion in powers of momentum,
which is demonstrated using an error analysis introduced by Lepage. A clear
graphical determination of the radius of convergence for the momentum expansion
is also obtained. I use these techniques to compare cutoff regularization, two
forms of dimensional regularization, and the dibaryon approach, using a simple
model for illustration. The naturalness of the parameters and predictions for
other observables are also shown.


title: What Effective Field Theory May Contribute to the Blast Program

abstract:
  Recent progress in using effective field theory to describe two nucleon
systems is reviewed.


title: QCD Sum Rules for Nucleon-Nucleon Interactions

abstract:
  The QCD sum rules for spin-dependent nucleon-nucleon interactions are
formulated and their physical implications are studied. The basic object of the
study is the correlation function of the nucleon interpolating field, where the
matrix element is taken with respect to the one-nucleon state. The dispersion
integral of the correlation function around the nucleon threshold is
investigated in detail. It turns out that the integral can be identified as a
measure of the nucleon-nucleon interaction strength, which is proportional to
the scattering length in the small scattering length limit and to one half of
the effective range in the large scattering length limit. New operators must be
taken into account in the OPE of the correlation function. There behavior
operators do not vanish when the matrix element is taken with respect to the
spin-nonaveraged one-nucleon state. The Wilson coefficients of such operators
are calculated. The sum rules obtained in this manner relate the spin-dependent
nucleon-nucleon interaction strengths with the spin-dependent nucleon matrix
elements of the quark-gluon composite operators. The sum rules imply that the
interaction is stronger in the spin-triplet channel than in the spin-singlet
channel, but that the spin-dependence of the nucleon-nucleon interactions is
rather small. In the spin-singlet channel the calculated strength is in
qualitative agreement with the empirical strength, which is estimated by the
empirical low energy scattering observables.


title: Delta isobar masses, large N_c relations, and the quark model

abstract:
  Motivated by recent remarks on the Delta+ mass and comparisons between the
quark model and relations based on large-N_c with perturbative flavor breaking,
two sets of Delta masses consistent with these constraints are constructed.
These two sets, based either on an experimentally determined mass splitting or
a quark model of isospin symmetry breaking, are shown to be inconsistent. The
model dependence of this inconsistency is examined, and suggestions for
improved experiments are made. An explicit quark model calculation and mass
relations based on the large-N_c limit with perturbative flavor breaking are
compared. The expected level of accuracy of such relations is realized in the
quark model, except for mass relations spanning more than one SU(6)
representation. It is shown that the Delta0 and Delta++ pole masses and Delta0
- Delta+ = (Delta- - Delta++)/3 about 1.5 MeV are more consistent with model
expectations than the analogous Breit-Wigner masses and their splittings.


title: Nonperturbative QCD with Modern Tools

abstract:
  I introduce and explore a range of topics of contemporary interest in
hadronic physics: from what drives the formation of a nonzero quark condensate
to the effect that mechanism has on light and heavy meson form factors, and the
properties of the quark-gluon plasma. The trail leads naturally through a
discussion of confinement, dynamical chiral symmetry breaking and bound state
structure: phenomena that require nonperturbative methods for their
explanation. In all of this, the necessary momentum-dependent modification of
the quark and gluon propagators plays a significant role.


title: Recent results from QMC relevant to TJNAF

abstract:
  We review recent calculations using the quark meson coupling model which
should be of particular interest at Jefferson Lab. In particular, we discuss
the change in the proton electric and magnetic form factors when it is bound in
a specific shell model orbit. Modern quasi-elastic electron scattering
experiments should be able to detect effects of the size predicted. We also
examine the mean field potential felt by an $\omega$ in a finite nucleus,
concluding that the $\omega$ should be bound by between 50 and 100 MeV.


title: omega-nucleus bound states in the Walecka model

abstract:
  Using the Walecka model, we investigate theoretically whether an omega meson
is bound to finite nuclei. We study several nuclei from ^{6}He to ^{208}Pb, and
compare the results with those in the quark-meson coupling (QMC) model. Our
calculation shows that deeper omega-nucleus bound states are predicted in the
Walecka model than in QMC. One can expect to detect such bound states in the
proposed experiment involving the (d,^3He) reaction at GSI.


title:
Relativistic Hartree-Bogoliubov description of the deformed N = 28
  region

abstract:
  Ground-state properties of neutron-rich $N \approx 28$ nuclei are described
in the framework of Relativistic Hartree Bogoliubov (RHB) theory. The model
uses the NL3 effective interaction in the mean-field Lagrangian, and describes
pairing correlations by the pairing part of the finite range Gogny interaction
D1S. Two-neutron separation energies and ground-state quadrupole deformations
that result from fully self-consistent RHB solutions, are compared with
available experimental data. The model predicts a strong suppression of the
spherical N=28 shell gap for neutron-rich nuclei: the $1f7/2 \to fp$ core
breaking results in deformed ground states. Shape coexistence is expected for
neutron-rich Si, S and Ar isotopes.


title: On final conditions in high energy heavy ion collisions

abstract:
  Motivated by the recent experimental observations, we discuss the freeze-out
properties of the fireball created in central heavy ion collisions. We find
that the freeze-out conditions, like temperature, velocity gradient near center
of the fireball, are similar for different colliding systems and beam energies.
This means that the transverse flow is stronger in the collisions of heavy
nuclei than that of the light ones.


title:
Critical analysis of quark-meson coupling models for nuclear matter and
  finite nuclei

abstract:
  Three versions of the quark-meson coupling (QMC) model are applied to
describe properties of nuclear matter and finite nuclei. The models differ in
the treatment of the bag constant and in terms of nonlinear scalar
self-interactions. As a consequence opposite predictions for the medium
modifications of the internal nucleon structure arise. After calibrating the
model parameters at equilibrium nuclear matter density, binding energies,
charge radii, single-particle spectra and density distributions of spherical
nuclei are analyzed and compared with QHD calculations. For the models which
predict a decreasing size of the nucleon in the nuclear environment,
unrealistic features of the nuclear shapes arise.


title:
Sum rule for the backward spin polarizability of the nucleon from a
  backward dispersion relation

abstract:
  A new sum rule for $\gamma_\pi$, the backward spin polarizability of the
nucleon, is derived from a backward-angle dispersion relation. Taking into
account single- and multi-pion photoproduction in the s-channel up to the
energy 1.5 GeV and resonances in the t-channel with mass below 1.5 GeV, it is
found for the proton and neutron that $[\gamma_\pi]_p$ = -39.5 +/- 2.4 and
$[\gamma_\pi]_n$ = 52.5 +/- 2.4, respectively, in units of 10^{-4} fm^4.


title: Modeling Pionic Fusion

abstract:
  Recently observed rare heavy ion fusion processes, where the entire available
energy is carried away by a single pion, is an example of extreme collectivity
in nuclear reactions. We calculate the cross section in the approximation of
sudden overlap, modeling the initial and final nuclei by moving harmonic
oscillator potentials. This allows for a fully quantum-mechanical treatment,
exact conservation of linear and angular momenta and fulfillment of the Pauli
principle. The results are in satisfactory agreement with data. Mass number
dependence and general trends of the process are discussed.


title: Universalities of Triplet Pairing in Neutron Matter

abstract:
  The fundamental structure of the full set of solutions of the BCS $^3 P_2$
pairing problem in neutron matter is established. The relations between
different spin-angle components in these solutions are shown to be practically
independent of density, temperature, and the specific form of the pairing
interaction. The spectrum of pairing energies is found to be highly degenerate.


title:
Bethe-Salpeter Approach for Meson-Meson Scattering in Chiral
  Perturbation Theory

abstract:
  The Bethe-Salpeter equation restores exact elastic unitarity in the s-
channel by summing up an infinite set of chiral loops. We use this equation to
show how a chiral expansion can be undertaken by successive approximations to
the potential which should be iterated. Renormalizability of the amplitudes in
a broad sense can be achieved by allowing for an infinite set of counter-terms
as it is the case in ordinary Chiral Perturbation Theory. Within this framework
we calculate the $\pi \pi$ scattering amplitudes both for s- and p-waves at
lowest order in the proposed expansion where a successful description of the
low-lying resonances ($\sigma$ and $\rho$) and threshold parameters is
obtained. We also extract the SU(2) low energy parameters ${\bar l}_{1,2,3,4}$
from our amplitudes.


title: ${\bar\Lambda}/{\bar p}$ ratios in heavy ion collisions at 11.6 AGeV/c

abstract:
  We attempt to explain the ${\bar \Lambda}/\bar p$ ratios measured in heavy
ion collisions at $11.6~{\rm A\cdot GeV}/c$ beam momentum within a hadronic
framework. This ratio is enhanced relative to corresponding ratios in $pp$
collisions, and is large when compared with thermal fits to heavy ion data.
Using a detailed cascade calculation, we show that different annihilation
cross--sections of $\bar \Lambda$'s and $\bar p$'s, and the net conversion of
$\bar p$'s to $\bar \Lambda$'s, do not account for the enhancement in central
collisions. For larger impact parameters, however, hadronic mechanisms may well
suffice to produce the observed enhancement. Uncertainties in elementary
cross--sections and formation times are considered.


title: Microscopic calculation of 6Li elastic and transition form factors

abstract:
  Variational Monte Carlo wave functions, obtained from a realistic Hamiltonian
consisting of the Argonne v18 two-nucleon and Urbana-IX three-nucleon
interactions, are used to calculate the 6Li ground-state longitudinal and
transverse form factors as well as transition form factors to the first four
excited states. The charge and current operators include one- and two-body
components, leading terms of which are constructed consistently with the
two-nucleon interaction. The calculated form factors and radiative widths are
in good agreement with available experimental data.


title:
The parity-violating pion-nucleon coupling constant from a realistic
  three flavor Skyrme model

abstract:
  We study the parity-violating pion-nucleon coupling $G_\pi$ in the framework
of a realistic three flavor Skryme model. We find a sizeable enhancement of
$G_\pi \simeq 0.8 ... 1.3 \cdot 10^{-7}$ compared to previous calculations in
two-flavor models with vector mesons. This strangeness enhancement stems from
induced kaon fields of the chiral soliton and the non-monotoneous dependence on
symmetry breaking of the nucleon matrix element of the flavor singlet piece of
the operator associated with these induced fields. Both features are sensitive
to four quark operators including an $\bar s s$ pair.


title:
The strength of the analog and Gamow-Teller giant resonances and
  hindrance of the 2\nu\beta\beta -decay rate

abstract:
  An approach for describing the hindrance of the nuclear 2\nu\beta\beta-decay
amplitude is proposed. The approach is based on a new formula obtained by a
model-independent transformation of the initial expression for the amplitude.
This formula takes explicitly into account the hindrance of the decay-amplitude
due to the presence of the collective Gamow-Teller state. Calculations are
performed within the simplest version of the approach. Calculated and
experimental 2\nu\beta\beta halve-lives are compared for a wide range of
nuclei.


title: Chiral dynamics of the nuclear equation of state

abstract:
  We present a new chiral power expansion scheme for the nuclear equation of
state. The scheme is effective in the sense that it is constructed to work
around nuclear saturation density. The leading and subleading terms are
evaluated and are shown to provide an excellent equation of state. As a further
application we considered the chiral quark condensate in nuclear matter.
Already at nuclear saturation density we predict a substantially smaller
reduction of the condensate as compared to conventional approaches.


title: Nuclear Physics

abstract:
  Nuclear Physics is the branch of physics that deals with the properties and
structure of matter on the hadronic level. In this article we review briefly
the history of this field, which has a major role in the development of our
understanding of nature. We then proceed to give an outline of a current
perspective of the field and of some of the issues that are now on its
frontiers.


title: Parton Cascades in High Energy Nuclear Collisions

abstract:
  This is a review of the parton cascade model (PCM) which provides a QCD-based
description of nucleus-nucleus reactions at very high energy. The PCM describes
the collision dynamics within the early and dense phase of the reaction in
terms of the relativistic, probabilistic transport of perturbative excitations
(partons) of the QCD vacuum, combined with the renormalization group flow of
the parton virtuality. The current state of numerical implementations of the
model, as well as its predictions for nuclear collisions at RHIC and LHC are
discussed.


title: Polarization Effects in Superdeformed Nuclei

abstract:
  A detailed theoretical investigation of polarization effects in superdeformed
nuclei is performed. In the pure harmonic oscillator potential it is shown that
when one particle (or hole) with the mass single-particle quadrupole moment
q_{nu} is added to a superdeformed core, the change of the electric quadrupole
moment can be parameterized as q_{eff}=e(bq_{nu}+a), and analytical expressions
are derived for the two parameters, $a$ and $b$. Simple numerical expressions
for q_{eff}(q_\nu}) are obtained in the more realistic modified oscillator
model. It is also shown that quadrupole moments of nuclei with up to 10
particles removed from the superdeformed core of 152Dy can be well described by
simply subtracting effective quadrupole moments of the active single-particle
states from the quadrupole moment of the core. Tools are given for estimating
the quadrupole moment for possible configurations in the superdeformed A
150-region.


title:
Determination of Li-6 -- He-4 interaction from multi-energy scattering
  data

abstract:
  We present the first successful potential model description of Li-6 -- He-4
scattering. The differential cross-sections for three energies and the vector
analyzing powers for two energies were fitted by a single potential with energy
dependent imaginary components. An essential ingredient is a set of Majorana
terms in each component. The potential was determined using a recently
developed direct data-to-potential inversion method which is a generalisation
of the IP S-matrix-to-potential inversion algorithm. We discuss the problems
related to this phenomenological approach, and discuss the relationship of our
results to existing and future theories.


title: Consequences of coarse grained Vlasov equations

abstract:
  The Vlasov equation is analyzed for coarse grained distributions resembling a
finite width of test-particles as used in numerical implementations. It is
shown that this coarse grained distribution obeys a kinetic equation similar to
the Vlasov equation, but with additional terms. These terms give rise to
entropy production indicating dissipative features due to a nonlinear mode
coupling The interchange of coarse graining and dynamical evolution is
discussed with the help of an exactly solvable model for the selfconsistent
Vlasov equation and practical consequences are worked out. By calculating
analytically the stationary solution of a general Vlasov equation we can show
that a sum of modified Boltzmann-like distributions is approached dependent on
the initial distribution. This behavior is independent of degeneracy and only
controlled by the width of test-particles. The condition for approaching a
stationary solution is derived and it is found that the coarse graining energy
given by the momentum width of test particles should be smaller than a quarter
of the kinetic energy. Observable consequences of this coarse graining are: (i)
spatial correlations in observables, (ii) too large radii of clusters or nuclei
in self-consistent Thomas-Fermi treatments, (iii) a structure term in the
response function resembling vertex correction correlations or internal
structure effects and (iv) a modified centroid energy and higher damping width
of collective modes.


title:
Formation of correlations at short time scales and consequences on
  interferometry methods

abstract:
  The formation of correlations due to collisions in an interacting nucleonic
system is investigated shortly after a disturbance. Results from one-time
kinetic equations are compared with the Kadanoff and Baym two-time equation
with collisions included in second order Born approximation. A reasonable
agreement is found for a proposed approximation of the memory effects by a
finite duration of collisions. The formation of correlations and the build up
time is calculated analytically for the high temperature and the low
temperature limit. This translates into a time dependent increase of the
effective temperature on time scales which interfere with standard fire ball
scenarios of heavy ion collisions. The consequences of the formation of
correlations on the two- particle interferometry are investigated and it is
found that standard extracted lifetimes should be corrected downwards.


title:
Self Consistent and Renormalized particle-particle RPA in a Schematic
  Model

abstract:
  The dynamical effects of ground state correlations for excitation energies
and transition strengths near the superfluid phase transition are studied in
the soluble two level pairing model, in the context of the particle-particle
self consistent Random Phase Approximation (SCRPA). Exact results are well
reproduced across the transition region, beyond the collapse of the standard
particle-particle Random Phase Approximation. The effects of two-body
correlation in the SCRPA are displayed explicitly.


title: Modified Zimanyi-Moszkowski Model for Finite Nuclei

abstract:
  By scaling the mesonic masses in the Walecka model, to the inverse of the
hadronic effective mass in medium, we generate the Zimanyi-Moszkowski (ZM)
models added to a surface term. For infinite nuclear matter, the surface term
vanishes and this new model becomes equivalent to the usual ZM model. For
finite nuclei calculations, the surface contribution changes the spin-orbit
splitting in the right experimental direction. Calculations for some nuclei are
presented.


title: Superallowed Fermi beta decay

abstract:
  Superallowed $0^+ \to 0^+$ nuclear beta decay provides a direct measure of
the weak vector coupling constant, $\GV$. We survey current world data on the
nine accurately determined transitions of this type, which range from the decay
of $^{10}$C to that of $^{54}$Co, and demonstrate that the results confirm
conservation of the weak vector current (CVC) but differ at the 98% confidence
level from the unitarity condition for the Cabibbo-Kobayashi-Maskawa (CKM)
matrix. We examine the reliability of the small calculated corrections that
have been applied to the data, and assess the likelihood of even higher quality
nuclear data becoming available to confirm or deny the discrepancy. Some of the
required experiments depend upon the availability of intense radioactive beams.
Others are possible today.


title: NN and NDelta Form Factors viewed from ChPT

abstract:
  I discuss recent work on nucleon form factors, magnetic strangeness in the
nucleon and the isovector nucleon-delta transition based on the broken chiral
symmetry of QCD, utilizing recent theoretical developments in ChPT.


title:
Study of relativistic bound state wave functions in quasielastic (e,e'p)
  reactions

abstract:
  The unpolarized response functions of the quasielastic $^{16}O(e,e^\prime
p)^{15}N$ reaction are calculated for three different types of relativistic
bound state wave functions. The wave functions are obtained from relativistic
Hartree, relativistic Hartree-Fock and density dependent relativistic Hartree
calculations that reproduce the experimental charge radius of $^{16}$O. The
sensitivity of the unpolarized response functions to the single particle
structure of the different models is investigated in the relativistic plane
wave impulse approximation. Redistributions of the momentum dependence in the
longitudinal and transverse response function can be related to the binding
energy of the single particle states. The interference responses $R_{LT}$ and
$R_{TT}$ reveal a strong sensitivity to the small component of the relativistic
bound state wave function.


title:
Relativistic RPA for Isobaric Analogue and Gamow-Teller Resonances in
  Closed Shell Nuclei

abstract:
  We perform a self-consistent relativistic RPA calculation for the isobaric
analogue and Gamow-Teller resonances based on relativistic mean field theory
results for the ground states of $^{48}$Ca, $^{90}$Zr and $^{208}$Pb. We use
the parameter set NL1 for the $\sigma$, $\omega$ and $\rho$ mesons, and
experimental values for the pion and nucleon. An extra parameter, related to
the intensity of the contact term in the pion-exchange interaction, is crucial
to reproduce the latter resonances.


title: Amplitude Analysis

abstract:
  Even if a `complete set' of experimental observables were measured for the
elastic scattering or photo/electroproduction of pseudoscalar mesons,
ambiguities would remain in the extracted partial-wave and isospin decomposed
amplitudes. As these problems are not widely understood, the present work
outlines the way model-dependence enters into analyses of data from both
hadronic and electromagnetic facilities.


title:
The Power Of Effective Field Theories In Nuclei: The Deuteron, NN
  Scattering and Electroweak Processes

abstract:
  We show how effectively effective quantum field theories work in nuclear
physics. Using the physically transparent cut-off regularization, we study the
simplest nuclear systems of two nucleons for both bound and scattering states
at a momentum scale much less than the pion mass. We consider all the static
properties of the deuteron, the two-nucleon scattering phase-shifts, the n + p
--> d + \gamma process at thermal energy and the solar proton fusion process p
+ p --> d + e(+) + \nu(e), and we demonstrate that these are all described with
great accuracy in the expansion to the next-to-leading order. We explore how a
"new" degree of freedom enters in an effective theory by turning on and off the
role of the pion in the Lagrangian.