title:
Explicitly Covariant Light-Front Dynamics and Relativistic Few-Body
  Systems

abstract:
  The wave function of a composite system is defined in relativity on a
space-time surface. In the explicitly covariant light-front dynamics, reviewed
in the present article, the wave functions are defined on the plane $\omega \cd
x=0$, where $\omega$ is an arbitrary four-vector with $\omega^2=0$. The
standard non-covariant approach is recovered as a particular case for $\omega =
(1,0,0,-1)$. Using the light-front plane is of crucial importance, while the
explicit covariance gives strong advantages emphasized through all the review.
  The properties of the relativistic few-body wave functions are discussed in
detail and are illustrated by examples in a solvable model. The
three-dimensional graph technique for the calculation of amplitudes in the
covariant light-front perturbation theory is presented.
  The structure of the electromagnetic amplitudes is studied. We investigate
the ambiguities which arise in any approximate light-front calculations, and
which lead to a non-physical dependence of the electromagnetic amplitude on the
orientation of the light-front plane. The elastic and transition form factors
free from these ambiguities are found for spin 0, 1/2 and 1 systems.
  The formalism is applied to the calculation of the relativistic wave
functions of two-nucleon systems (deuteron, scattering state), with particular
attention to the role of their new components in the deuteron elastic and
electrodisintegration form factors and to their connection with meson exchange
currents. Straigthforward applications to the pion and nucleon form factors and
the $\rho-\pi$ transition are also made.


title:
Inclusive quasielastic scattering of polarized electrons from polarized
  nuclei

abstract:
  The inclusive quasielastic response functions that appear in the scattering
of polarized electrons from polarized nuclei are computed and analyzed for
several closed-shell-minus-one nuclei with special attention paid to 39K.
Results are presented using two models for the ejected nucleon --- when
described by a distorted wave in the continuum shell model or by a plane wave
in PWIA with on- and off-shell nucleons. Relativistic effects in kinematics and
in the electromagnetic current have been incorporated throughout. Specifically,
the recently obtained expansion of the electromagnetic current in powers only
of the struck nucleon's momentum is employed for the on-shell current and the
effects of the first-order terms (spin-orbit and convection) are compared with
the zeroth-order (charge and magnetization) contributions. The use of polarized
inclusive quasielastic electron scattering as a tool for determining
near-valence nucleon momentum distributions is discussed.


title:
Solutions of the Faddeev-Yakubovsky equations for the four nucleons
  scattering states

abstract:
  The Faddeev-Yakubowsky equations in configuration space have been solved for
the four nucleon system. The results with an S-wave interaction model in the
isospin approximation are presented. They concern the bound and scattering
states below the first three-body threshold. The elastic phase-shifts for the
N+NNN reaction in different ($S,T$) channels are given and the corresponding
low energy expansions are discussed. Particular attention is payed to the n+t
elastic cross section. Its resonant structure is well described in terms of a
simple NN interaction. First results concerning the S-matrix for the coupled
N+NNN-NN+NN channels and the strong deuteron-deuteron scattering length are
obtained.


title:
A Perturbative Calculation of the Electromagnetic Form Factors of the
  Deuteron

abstract:
  Making use of the effective field theory expansion recently developed by the
authors, we compute the electromagnetic form factors of the deuteron
analytically to next-to-leading order (NLO). The computation is rather simple,
and involves calculating several Feynman diagrams, using dimensional
regularization. The results agree well with data and indicate that the
expansion is converging. They do not suffer from any ambiguities arising from
off-shell versus on-shell amplitudes.


title: Electric polarizability of nuclei and a longitudinal sum rule

abstract:
  Recently, a longitudinal sum rule for the electric polarizability of nuclei
was used to revise a relativistic correction in a dipole sum rule for the
polarizability (nucl-th/9802011). This revision is shown to be wrong because of
neglecting an asymptotic contribution in the underlying dispersion relation.
The status and correct use of the longitudinal sum rule is clarified.


title: Including Pions

abstract:
  Recent progress in using effective field theory to describe systems with two
nucleons is discussed with particular emphasis placed on the inclusion of
pions. Inconsistencies arising in Weinberg's power counting are demonstrated
with two concrete examples. A consistent power-counting scheme is discussed in
which pion exchange is sub-leading to local four-nucleon operators. NN
scattering in the 1S0 and 3S1-3D1 channels is calculated at sub-leading order
and compared with data.


title:
Evidence of early multi-strange hadron freeze-out in high energy nuclear
  collisions

abstract:
  Recently reported transverse momentum distributions of strange hadrons
produced in Pb(158AGeV) on Pb collisions and corresponding results from the
relativistic quantum molecular dynamics (RQMD) approach are examined. We argue
that the experimental observations favor a scenario in which multi-strange
hadrons are formed and decouple from the system rather early at large energy
densities (around 1 GeV/fm$^3$). The systematics of the strange and non-strange
particle spectra indicate that the observed transverse flow develops mainly in
the late hadronic stages of these reactions.


title:
Comments on some recent papers on the hyperspherical approach in
  few-body systems

abstract:
  Recent papers by Kievsky, Viviani, and Rosati are commented. It is pointed
out that the techniques for treatment few-body reactions and bound states in
the framework of the hyperspherical approach presented in those papers as
original ones were in fact known and have been applied previously.


title: Photon-induced two-nucleon knockout reactions to discrete final states

abstract:
  Cross sections and photon asymmetries of the exclusive 16O(\gamma,pn)14N and
16O(\gamma,pp)14C knockout reactions are calculated for transitions to the
low-lying discrete final states of the residual nucleus in the photon-energy
range between 100 and 400 MeV. Exclusive reactions may represent a test of
reaction mechanisms and a promising tool for investigating the dynamics of
nucleon pairs in different states. Cross sections and asymmetries for both
(\gamma,pn) and (\gamma,pp) turn out to be only slightly affected by
short-range correlations and dominated by two-body currents. Therefore,
two-nucleon knockout reactions induced by real photons appear well suited to
investigate the nuclear current and the selectivity of individual transitions
to its different components.


title: rho-omega mixing in relativistic heavy-ion collisions

abstract:
  We show that even moderate excess of neutrons over protons in nuclear matter,
such as in ${}^{208} Pb$, can lead to large $\rho$-$\omega$ mixing at densities
of the order of twice the nuclear saturation density and higher. The typical
mixing angle is of the order of $10^o$. The mixing may result in noticeable
shifts of the positions and widths of resonances. We also analyze temperature
effects and find that temperatures up to 50 MeV have practically no effect on
the mixing.


title: Hamiltonian Flow Equations for the Lipkin Model

abstract:
  We derive Hamiltonian flow equations giving the evolution of the Lipkin
Hamiltonian to a diagonal form using continuous unitary transformations. To
close the system of flow equations, we present two different schemes. First we
linearize an operator with three pairs of creation and destruction operators by
reducing it to the $z$ component of the quasi spin. We obtain the well known
RPA-result in the limit of large particle number. In the second scheme we
introduce a new operator which improves the resulting spectrum considerably
especially for few particles.


title:
Regularization and the potential of effective field theory in
  nucleon-nucleon scattering

abstract:
  This paper examines the role that regularization plays in the definition of
the potential used in effective field theory (EFT) treatments of the
nucleon-nucleon interaction. I consider $NN$ scattering in $S$-wave channels at
momenta well below the pion mass. In these channels (quasi-)bound states are
present at energies well below the scale $m_\pi^2/M$ expected from naturalness
arguments. I ask whether, in the presence of such a shallow bound state, there
is a regularization scheme which leads to an EFT potential that is both useful
and systematic. In general, if a low-lying bound state is present then cutoff
regularization leads to an EFT potential which is useful but not systematic,
and dimensional regularization with minimal subtraction leads to one which is
systematic but not useful. The recently-proposed technique of dimensional
regularization with power-law divergence subtraction allows the definition of
an EFT potential which is both useful and systematic.


title:
Statistical Fluctuations of Electromagnetic Transition Intensities in
  pf-Shell Nuclei

abstract:
  We study the fluctuation properties of E2 and M1 transition intensities among
T=0,1 states of A = 60 nuclei in the framework of the interacting shell model,
using a realistic effective interaction for pf-shell nuclei with a Ni56 as a
core. It is found that the B(E2) distributions are well described by the
Gaussian orthogonal ensemble of random matrices (Porter-Thomas distribution)
independently of the isobaric quantum number T_z. However, the statistics of
the B(M1) transitions is sensitive to T_z: T_z=1 nuclei exhibit a Porter-Thomas
distribution, while a significant deviation from the GOE statistics is observed
for self-conjugate nuclei (T_z=0).


title:
Two Center Light Cone Calculation of Pair Production Induced by
  Ultrarelativistic Heavy Ions

abstract:
  An exact solution of the two center time-dependent Dirac equation for pair
production induced by ultrarelativistic heavy ion collisions is presented.
Cross sections to specific final states approach those of perturbation theory.
Multiplicity rates are reduced from perturbation theory.


title:
Photoproduction of phi mesons from the proton: Polarization observables
  and strangeness in the nucleon

abstract:
  The polarization observables in phi meson photoproduction is studied to probe
the strangeness content of the nucleon. In addition to the dominant diffractive
production and the one-pion-exchange process, we take into account the direct
knockout mechanism that arises from the possible hidden strangeness content of
the nucleon. We find that some double polarization observables are very
sensitive to the strangeness content of the proton because of the different
spin structures of the amplitudes associated with different mechanisms. This
suggests that such measurements could be very useful in probing the strangeness
content in the proton. The orbitally excited quark-cluster configurations in
the proton are included in the calculation and found to have little effect.


title: $\rho - \omega$ Mixing at High Temperature and Density

abstract:
  The temperature and density dependence of the $\rho-\omega$ mixing amplitude
has been studied from a purely hadronic model. The in-medium baryon masses and
chemical potentials have been obtained at the Mean Field (MF) Level and these
results have been used to calculate the mixing amplitude. It has been observed
that the mixing amplitude changes substantially at high temperature and
density.


title:
Au+Au central collisions at 150, 250 and 400 AMeV energies in QMD with
  relativistic forces

abstract:
  An extensive comparison of the recent experimental data published by the FOPI
collaboration at GSI with the results of a relativistically covariant
formulation of a QMD code is presented. For most of the quantities we find
agreement with the experimental results showing that the derived force has a
reasonable momentum dependence.


title: Radial flow of kaon mesons in heavy ion reactions

abstract:
  This work investigates the collective motion of kaons in heavy ion reactions
at SIS energies (about 1-2 GeV/nucleon). A radial collective flow of $K^+$
mesons is predicted to exist in central Au + Au collisions, which manifests in
a characteristic "shoulder-arm" shape of the transverse mass spectrum of the
midrapidity $K^+$ mesons. The $K^+$ radial flow arises from the repulsive $K^+$
mean field in nuclear matter. In spite of a strong reabsorption and
rescattering the attractive $K^-$ mean field leads as well to a collective
radial flow of $K^-$ mesons. The $K^-$ radial flow, however, is different from
that of $K^+$ mesons and can be observed by a characteristic "concave"
structure of the transverse mass spectrum of the $K^-$ mesons emitted at
midrapidity. The kaon radial flows can therefore serve as a novel tool for the
investigation of kaon properties in dense nuclear matter.


title: Backward Elastic p3He Scattering at Energies 1 - 2 GeV

abstract:
  The two-body transfer amplitude for the rearrangement process i+(jkl) -
j+(ikl) is constructed on the basis of technique of 4-dimensional covariant
nonrelativistic graphs. The developed formalism is applied to describing
backward elastic $p^3He$ scattering in the energy range 0.5 - 1.7 GeV.
Numerical calculations performed using the 5- channel wave function of the
$^3He$ nucleus show that the transfer of a noninteracting np- pair dominates
and explains satisfactorily the energy and angular dependence of the
differential cross section at energies 0.9 - 1.7$ GeV.
  A weak sensitivity to high momentum components of the $~^3He$ wave function
in spite of large momentum transfer as well as a very important role of
rescatterings in the initial and final states are established.


title: Role of Deuteron NN^* -components in proceses pd - dp and pd- dN^*

abstract:
  The contribution of nucleon isobar $N^*$ exchanges to backward elastic
pd-scattering is calculated on the basis of deuteron 6q-model and found to be
negligible in comparison with the neutron exchange. It is shown that the pole
amplitude of neutron pickup from the deuteron $nN^*$-component is favoured in
the reaction $pd\to dN^*$ for backward going $N^*(1440)$ and $N^*(1710)$ at
kinetic energy of incident proton of 1.5--2 GeV whereas the triangular diagram
with subprocess $pp\to d\pi^+$ related to the usual $pn-$component of deuteron
is considerable suppressed.


title: Photoexcitation of the Nucleon in the Constituent Quark Model

abstract:
  Photoexcitation of the nucleon is studied in the framework of the constituent
quark model with nonrelativistic quark-quark interactions. Utilizing the
dominance of the pairwise structure of the relevant three-quark potential, the
bound and excited state wave functions have been constructed using the
Faddeev-type Integrodifferential Equation Approach. The method is based on the
Hyperspherical Harmonics expansion and takes two-body correlations exactly into
account and therefore reliable wave functions, required in photo processes, can
be obtained. The integrated photoabsorption cross sections for the E1-and
M1-transitions are calculated and compared with experimental values as well as
with those of other theoretical calculations. Our results, in overall, are in
good to very good agreement with the experimental values.


title: The $pd\to ^3H_\Lambda K^+$ reaction cross section

abstract:
  The one- and two-step mechanisms of the $pd\to ^3H_\Lambda K^+$ reaction in
the range of incident proton kinetic energy 1.13-3.0 GeV have been
investigated. A remarkable peculiarity of the two-step mechanism which
incorporates subprocesses $pp\to d\pi ^+$ and $\pi^+n\to K^+\Lambda $ is the so
called velocity matching providing the presence of all intermediate particles
nearly to the on-mass-shell. The differential cross section has been calculated
using a realistic model for the hypertritium $^3H_\Lambda $ wave function. The
maximum value of the cross section is estimated as $\sim $1nb/sr. The
contribution of the one-step mechanism with the elementary process $pN\to
NK\Lambda $ into the cross section has been found to be two - three orders of
magnitude smaller in comparison with the two-step mechanism.


title: Gauge-invariant tree-level photoproduction amplitudes with form factors

abstract:
  We show how the gauge-invariance formulation given by Haberzettl is
implemented in practice for photoproduction amplitudes at the tree level with
form factors describing composite nucleons. We demonstrate that, in contrast to
Ohta's gauge-invariance prescription, this formalism allows electric current
contributions to be multiplied by a form factor, i.e., it does not require that
they be treated like bare currents. While different in detail, this
nevertheless lends support to previous ad hoc approaches which multiply the
Born amplitudes by an overall form factor. Numerical results for kaon
photoproduction off the nucleon are given. They show that the gauge procedure
by Haberzettl leads to much improved $\chi^2$ values as compared to Ohta's
prescription.


title: Pre-Equilibrium Evolution of QCD Plasma :An Appraisal

abstract:
  We discuss, in this review, the existing models for the production of QGP in
Relativistic Heavy Ion Collisions. We shall try to give a brief description of
the models available for the pre-equilibrium production of QGP, ranging from
soft process dominated QCD regime to the pQCD dominated regime. We also present
the estimates for the initial energy density, the temperature and the
thermalisation time -- available from each of these studies. Finally, we shall
address the questions regarding thermalisation, color equilibration and
chemical equilibration of the produced QGP in different experimental
facilities.


title: Non-perturbative chiral approach to Kp -->gamma Y reactions

abstract:
  A recently developed nonperturbative chiral approach to describe the S=-1
meson-baryon reactions has been extended to investigate the near threshold $K^-
p \to \gamma \Lambda, \gamma \Sigma^0$ reactions. With the parameters governed
by chiral SU(3) symmetry, we show that the predicted branching ratios
$\Gamma_{K^- p \to \gamma \Lambda}/\Gamma_{K^- p \to all}$ and $\Gamma_{K^-p\to
\gamma \Sigma^0}/\Gamma_{K^- p \to all}$ are close to the experimental values.
The coupling with the $\eta$ channels, which was shown to be important in the
$S=-1$ meson-baryon reactions, is also found to be significant here. Our
results are consistent with the interpretation of the $\Lambda(1405)$ as a
quasi-bound meson-baryon state as found in other similar chiral approaches.


title: Relativistic y-scaling and the Coulomb sum rule in nuclei

abstract:
  In this paper dividing factors GL and GT are constructed for the longitudinal
and transverse responses of the relativistic Fermi gas in such a way that the
reduced responses so obtained scale. These factors parallel another dividing
factor studied previously, HL, that yields a (different) reduced response which
fulfills the Coulomb sum rule. GL, GT and HL are all found to be only very
weakly model-dependent, thus providing essentially universal dividing factors.
To explore the residual degree of dependence which remains, the scaling and sum
rule properties of several specific models have been considered. It is seen
that the relativistic Fermi gas (by construction) and also typical shell-model
reduced responses successfully scale and satisfy the Coulomb sum rule, as do
experimental results at medium to high momentum transfers. On the other hand,
it is observed that the quantum hadrodynamic model does so only if interaction
effects become weaker with increasing momentum transfer, as predicted in the
most recent versions of that model.


title: Widths of Isobaric Analog Resonances: a microscopic approach

abstract:
  A self-consistent particle-phonon coupling model is used to investigate the
properties of the isobaric analog resonance in $^{208}$Bi. It is shown that
quantitative agreement with experimental data for the energy and the width can
be obtained if the effects of isospin-breaking nuclear forces are included, in
addition to the Coulomb force effects. A connection between microscopic model
predictions and doorway state approaches which make use of the isovector
monopole resonance, is established via a phenomenological ansatz for the
optical potential.


title: Pion Correlations and Two-Particle Bound States

abstract:
  A method to investigate possible loosely bound dibaryon states is suggested.
The momentum dependence of a two-pion correlation function is shown to depend
on the (non)existence of a bound state.


title:
Three-body halos. V. Computations of continuum spectra for Borromean
  nuclei

abstract:
  We solve the coordinate space Faddeev equations in the continuum. We employ
hyperspherical coordinates and provide analytical expressions allowing easy
computation of the effective potentials at distances much larger than the
ranges of the interactions where only s-waves in the different Jacobi
coordinates couple. Realistic computations are carried out for the Borromean
halo nuclei 6He (n+n+\alpha) for J\pi = 0+-, 1+-, 2+- and 11Li (n+n+9Li) for
(1/2)+-, (3/2)+-, (5/2)+-. Ground state properties, strength functions, Coulomb
dissociation cross sections, phase shifts, complex S-matrix poles are computed
and compared to available experimental data. We find enhancements of the
strength functions at low energies and a number of low-lying S-matrix poles.


title:
Equation of State, Spectra and Composition of Hot and Dense Infinite
  Hadronic Matter in a Microscopic Transport Model

abstract:
  Equilibrium properties of infinite relativistic hadron matter are
investigated using the Ultrarelativistic Quantum Molecular Dynamics (UrQMD)
model. The simulations are performed in a box with periodic boundary
conditions. Equilibration times depend critically on energy and baryon
densities. Energy spectra of various hadronic species are shown to be isotropic
and consistent with a single temperature in equilibrium. The variation of
energy density versus temperature shows a Hagedorn-like behavior with a
limiting temperature of 130$\pm$10 MeV. Comparison of abundances of different
particle species to ideal hadron gas model predictions show good agreement only
if detailed balance is implemented for all channels. At low energy densities,
high mass resonances are not relevant; however, their importance raises with
increasing energy density. The relevance of these different conceptual
frameworks for any interpretation of experimental data is questioned.


title: Intrinsic structure of two-phonon states in the interacting boson model

abstract:
  A general study of excitations up to two-phonon states is carried out using
the intrinsic-state formalism of the Interacting Boson Model (IBM). Spectra and
transitions for the different dynamical symmetries are analyzed and the
correspondence with states in the laboratory frame is established. The
influence of multi-phonon states is discussed. The approach is useful in
problems where the complexity of the IBM spectrum renders the analysis in the
laboratory frame difficult.


title: Odd-Even Staggering of Nuclear Masses: Pairing or Shape Effect?

abstract:
  The odd-even staggering of nuclear masses was recognized in the early days of
nuclear physics. Recently, a similar effect was discovered in other finite
fermion systems, such as ultrasmall metallic grains and metal clusters. It is
believed that the staggering in nuclei and grains is primarily due to pairing
correlations (superconductivity), while in clusters it is caused by the
Jahn-Teller effect. We find that, for light and medium-mass nuclei, the
staggering has two components. The first one originates from pairing while the
second, comparable in magnitude, has its roots in the deformed mean field.


title:
Power Counting and the Renormalization Group for an Effective
  Description of NN Scattering

abstract:
  I outline the power counting scheme recently introduced by M. Savage, M. Wise
and myself for the effective field theory treatment of nucleon-nucleon
scattering. It is particularly useful for describing systems with a large
scattering length, and differs from Weinberg's power counting. A
renormalization group analysis plays a big role in determining the order of a
given operator. Pions are ignored in this discussion; how to incorporate them
is discussed in M. Savage's talk, nucl-th/9804034.


title: Pseudovector components of the pion, pi^0 -> gamma gamma, and F_pi(q^2)

abstract:
  As a consequence of dynamical chiral symmetry breaking the pion
Bethe-Salpeter amplitude necessarily contains terms proportional to gamma_5
gamma.P and gamma_5 gamma.k, where k is the relative and P the total momentum
of the constituents. These terms are essential for the preservation of low
energy theorems, such as the Gell-Mann--Oakes-Renner relation and those
describing anomalous decays of the pion, and to obtaining an electromagnetic
pion form factor that falls as 1/q^2 for large q^2, up to calculable
ln(q^2)-corrections. In a simple model, which correlates low- and high-energy
pion observables, we find q^2 F_pi(q^2) ~ 0.12 - 0.19 GeV^2 for q^2 >~10 GeV^2.


title:
Peripheral N$\alpha$ Scattering: A Tool For Identifying The Two Pion
  Exchange Component Of The NN Potential

abstract:
  We study elastic N$\alpha $ scattering and produce a quantitative correlation
between the range of the effective potential and the energy of the system. This
allows the identification of the waves and energies for which the scattering
may be said to be peripheral. We then show that the corresponding phase shifts
are sensitive to the tail of the NN potential, which is due to the exchange of
two pions. However, the present uncertainties in the experimental phase shifts
prevent the use of N$\alpha $ scattering to discriminate the existing models
for the NN interaction.


title:
Electron Propagation in the Field of Colliding Nuclei at
  Ultrarelativistic Energies

abstract:
  We calculate the asymptotic high-energy amplitude for electrons scattering at
one ion as well as at two colliding ions, respectively, by means of
perturbation theory. We show that the interaction with one ion eikonalizes and
that the interaction with two ions causally decouples. We are able to put
previous results on perturbative grounds and propose further applications for
the obtained rules for interactions on the light cone. The formalism will be of
use for the calculation of Coulomb corrections to electron-positron pair
creation in heavy ion collisions. Finally we discuss the results and inherent
dangers of the employed approximations.


title: Low-Mass Dileptons from in-Medium Hadronic Interactions

abstract:
  Medium Effects in low-mass dilepton production in ultra-relativistic
heavy-ion collisions are investigated using hadronic models. The rescattering
of pions and rho mesons within a hot and dense hadron gas leads to substantial
modifications in the $\pi^+\pi^- \to e^+ e^-$ annihilation process, which are
shown to be important for understanding the recently observed dilepton
enhancement at the CERN-SpS. Possible implications for the nature of the chiral
phase transition are outlined.


title:
Thermodynamical properties of a mean-field plus pairing model and
  applications for the Fe nuclei

abstract:
  A mean-field plus pairing model for atomic nuclei in the Fe region was
studied using a finite-temperature quantum Monte-Carlo method. We present
results for thermodynamical quantities such as the internal energy and the
specific heat. These results give indications of a phase transition related to
the pairing amongst nucleons, around temperatures of 0.7 MeV. The influence of
the residual interaction and of the size of the model space on the nuclear
level densities is discussed too.


title:
Center-of-mass effects on the quasi-hole spectroscopic factors in the
  16O(e,e'p) reaction

abstract:
  The spectroscopic factors for the low-lying quasi-hole states observed in the
16O(e,e'p)15N reaction are reinvestigated with a variational Monte Carlo
calculation for the structure of the initial and final nucleus. A computational
error in a previous report is rectified. It is shown that a proper treatment of
center-of-mass motion does not lead to a reduction of the spectroscopic factor
for $p$-shell quasi-hole states, but rather to a 7% enhancement. This is in
agreement with analytical results obtained in the harmonic oscillator model.
The center-of-mass effect worsens the discrepancy between present theoretical
models and the experimentally observed single-particle strength. We discuss the
present status of this problem, including some other mechanisms that may be
relevant in this respect.


title: Nuclear effects in the F3 structure function

abstract:
  By using a relativistic framework and accurate nuclear spectral functions we
evaluate the ratio F_{3A}/AF_{3N} of deep inelastic neutrino scattering.
Parametrizations of this ratio for different values of Q^2 are provided. These
results should be useful for taking into account the nuclear effects in
analyses of experimental data in neutrino reactions in nuclear targets, and
test QCD predictions for the nucleon structure functions. In particular, the
size of the nuclear corrections is of the same order of magnitude as the size
of the QCD corrections to the Gross-Llewellyn Smith sum rule.


title: New Excitation Mode of the Nucleon?

abstract:
  We consider properties of narrow baryon states observed recently in reaction
$pp\to p\pi^+X$. Two lowest of them (with mass 1004 and 1044 MeV, respectively)
are stable against strog decay. Moreover we conclude that they cannot decay to
$\gamma N$ and thus this states are a kind of metastable levels in quark
system. The simplest decay channel is assumed to be $2\gamma N$ and possible
quark configuration with such properties is discussed. New experiment for
verification of status of this states in $\gamma N$ collision is proposed.


title: Strange Decays of Nonstrange Baryons

abstract:
  The strong decays of excited nonstrange baryons into the final states Lambda
K, Sigma K, and for the first time into Lambda(1405) K, Lambda(1520) K,
Sigma(1385) K, Lambda K*, and Sigma K*, are examined in a relativized quark
pair creation model. The wave functions and parameters of the model are fixed
by previous calculations of N pi and N pi pi, etc., decays. Our results show
that it should be possible to discover several new negative parity excited
baryons and confirm the discovery of several others by analyzing these final
states in kaon production experiments. We also establish clear predictions for
the relative strengths of certain states to decay to Lambda(1405) K and
Lambda(1520) K, which can be tested to determine if a three-quark model of the
Lambda(1405) K is valid. Our results compare favorably with the results of
partial wave analyses of the limited existing data for the Lambda K and Sigma K
channels. We do not find large Sigma K decay amplitudes for a substantial group
of predicted and weakly established negative-parity states, in contrast to the
only previous work to consider decays of these states into the strange final
states Lambda K and Sigma K.


title: A consistent explanation of the Roper phenomenology

abstract:
  We study the electromagnetic transitions of the Roper N(1440) resonance. Our
results, when combined with the previously obtained for the mass and the pionic
strong decay widths of the Roper, show that within a non-relativistic
constituent quark model scheme, a comprehensible understanding of the Roper
phenomenology can be achieved. They also seem to support the view of the Roper
as a radial excitation of the nucleon, though more experimental data are needed
to reach a definitive conclusion.


title:
$K^-$ - nucleus relativistic mean field potentials consistent with
  kaonic atoms

abstract:
  $K^-$ atomic data are used to test several models of the $K^-$ nucleus
interaction. The t($\rho$)$\rho$ optical potential, due to coupled channel
models incorporating the $\Lambda$(1405) dynamics, fails to reproduce these
data. A standard relativistic mean field (RMF) potential, disregarding the
$\Lambda$(1405) dynamics at low densities, also fails. The only successful
model is a hybrid of a theoretically motivated RMF approach in the nuclear
interior and a completely phenomenological density dependent potential, which
respects the low density theorem in the nuclear surface region. This best-fit
$K^-$ optical potential is found to be strongly attractive, with a depth of 180
\pm 20 MeV at the nuclear interior, in agreement with previous phenomenological
analyses.


title:
Reply to the paper of V.D. Efros: Comments in some recent papers on the
  Hyperspherical approach in few--body system

abstract:
  Few days ago V.D. Efros submitted a preprint to nucl-th containing criticisms
of our recent research activity on bound and scattering states of A=3, 4
nucleons. As a consequence, we are forced to examine the essence of the
controversy and of the comments contained in that preprint. These are the
motivations of the present paper.


title:
Particle-hole state densities with non-equidistant single-particle
  levels

abstract:
  The correct use of energy-dependent single-particle level (s.p.l.) densities
within particle-hole state densities based on the equidistant spacing model
(ESM) is analysed. First, an analytical expression is obtained following the
convolution of energy-dependent excited-particle and hole densities. Next, a
comparison is made with results of the ESM formula using average s.p.l.
densities for the excited particles and holes, respectively. The Fermi-gas
model (FGM) s.p.l. densities calculated at the corresponding average excitation
energies are used in both cases. The analysis concerns also the density of
particle-hole bound states. The pairing correlations are taken into account
while the comparison of various effects includes the exact correction for the
Pauli exclusion principle. Quantum-mechanical s.p.l. densities and the
continuum effect can also match a corresponding FGM formula, suitable for use
within the average energy-dependent partial state density in multistep reaction
models.


title: g_{\pi \Lambda \Sigma} and g_{K \Sigma \Xi} from QCD sum rules

abstract:
  The coupling constants g_{\pi \Lambda \Sigma} and g_{K \Sigma \Xi} are
calculated in the QCD sum rule approach using the three-point function method
and taking into account the SU(3) symmetry breaking effects. The pattern of
SU(3) breaking appears to be different from that based on SU(3) relations.


title:
Structure and decay properties of spin-dipole giant resonances within a
  semimicroscopical approach

abstract:
  A semimicroscopical approach is applied to calculate: (i) strength functions
for the charge-exchange spin-dipole giant resonances in the 208Pb parent
nucleus; (ii) partial and total branching ratios for the direct proton decay of
the resonance in 208Bi. The approach is based on continuum-RPA calculations of
corresponding reaction-amplitudes and phenomenological description of the
doorway-state coupling to many-quasiparticle configurations. The only
adjustable parameter needed for the description is found by comparison of the
calculated and experimental total widths of the resonance. Other model
parameters used in calculations are taken from independent data. The calculated
total branching ratio is found to be in reasonable agreement with the
experimental value.


title: Nuclear Interference effects in 8B sub-Coulomb breakup

abstract:
  The breakup of $^8$B on $^{58}$Ni below the Coulomb barrier was measured
recently with the aim of determining the Coulomb breakup components. We
reexamine this reaction, and perform one step quantum-mechanical calculations
that include E1, E2 and nuclear contributions. We show that the nuclear
contribution is by no means negligible at the intermediate angular range where
data was taken. Our results indicate that, for an accurate description of this
reaction, Coulomb E1, E2 and nuclear processes all have to be taken into
account.


title:
Low-energy and low-momentum representation of the virtual Compton
  scattering amplitude

abstract:
  We perform an expansion of the virtual Compton scattering amplitude for low
energies and low momenta and show that this expansion covers the transition
from the regime to be investigated in the scheduled photon electroproduction
experiments to the real Compton scattering regime.
  We discuss the relation of the generalized polarizabilities of virtual
Compton scattering to the polarizabilities of real Compton scattering.


title:
Deduction of the quantum numbers of low-lying states of 4-nucleon
  systems based on symmetry

abstract:
  The inherent nodal structures of the wavefunctions of 4-nucleon systems have
been investigated. The quantum numbers of the excited states (resonances) have
been deduced. It was found that all the T=0 even-parity resonances are
dominated by {2,1,1} component with L=1, all the T=0 odd-parity resonances are
dominated by {3,1} component with L=1, and all the T=1 odd-parity resonances
are also dominated by {3,1} component with L=1. The understanding of the
inherent nodal structure is found to be crucial to a systematic understanding
of the spectrum.


title: Exact 4He Spectral Function in a Semirealistic NN Potential Model

abstract:
  The spectral function of 4He is calculated with the Lorentz integral
transform method in a large energy and momentum range. The excitation spectrum
of the residual 3N-system is fully taken into account. The obtained spectral
function is used to calculate the quasi elastic longitudinal (e,e') response
R_l of 4He for q=300, 400, and 500 MeV/c. Comparison with the exact R_l shows a
rather sizeable disagreement except in the quasi elastic peak, where the
differences reduce to about 10% at q=500 MeV/c. It is shown as well that very
simple momentum distribution approximations for the spectral function provide
practically the same results for R_l as the exact spectral function.


title:
A model for nuclear matter fragmentation: phase diagram and cluster
  distributions

abstract:
  We develop a model in the framework of nuclear fragmentation at thermodynamic
equilibrium which can be mapped onto an Ising model with constant
magnetization. We work out the thermodynamic properties of the model as well as
the properties of the fragment size distributions. We show that two types of
phase transitions can be found for high density systems. They merge into a
unique transition at low density. An analysis of the critical exponents which
characterize observables for different densities in the thermodynamic limit
shows that these transitions look like continuous second order transitions.


title:
On the determination of the pion effective mass in nuclei from pionic
  atoms

abstract:
  The binding energies of the deeply bound 1s and 2p states in pionic atoms of
$^{207}$Pb, recently established experimentally in the $^{208}$Pb(d,$^3$He)
reaction, have been used by several groups to derive the pion effective mass in
nuclear matter. We show that these binding energies are fully consistent with
`normal' pionic atoms and that the real part of the pion-nucleus potential at
the center of $^{207}$Pb is 28$\pm$3 MeV and not 20 MeV as suggested
previously.


title: Axial Vector Coupling Constant in Chiral Colour Dielectric Model

abstract:
  The axial vector coupling constants of the $\beta$ decay processes of neutron
and hyperon are calculated in SU(3) chiral colour dielectric model (CCDM).
Using these axial coupling constants of neutron and hyperon, in CCDM we
calculate the integrals of the spin dependent structure functions for proton
and neutron. Our result is similar to the results obtained by MIT bag and
Cloudy bag models.


title: New analytic solutions of the non-relativistic hydrodynamical equations

abstract:
  New solutions are found for the non-relativistic hydrodynamical equations.
These solutions describe expanding matter with a Gaussian density profile. In
the simplest case, thermal equilibrium is maintained without any interaction,
the energy is conserved, and the process is isentropic. More general solutions
are also obtained that describe explosions driven by heat production, or
contraction of the matter caused by energy loss.


title: Neutrino capture by r-process waiting-point nuclei

abstract:
  We use the Quasiparticle Random Phase Approximation to include the effects of
low-lying Gamow-Teller and first forbidden strength in neutrino capture by very
neutron-rich nuclei with N = 50, 82, or 126. For electron neutrinos in what is
currently considered the most likely r-process site the capture cross sections
are two or more times previous estimates. We briefly discuss the reliability of
our calculations and their implications for nucleosynthesis.


title:
About the Equivalence of Cut-off and Renormalised Effective Field
  Theories

abstract:
  The equivalence of subtractively renormalized and cut-off effective field
theories is demonstrated for the example of very low energy effective field
theory for the nucleon-nucleon interaction.


title: Meson-Baryon Form Factors in Chiral Colour Dielectric Model

abstract:
  The renormalised form factors for pseudoscalar meson-baryon coupling are
computed in chiral colour dielectric model. This has been done by rearranging
the Lippmann-Schwinger series for the meson baryon scattering matrix so that it
can be expressed as a baryon pole term with renormalized form factors and
baryon masses and the rest of the terms which arise from the crossed diagrams.
Thus we are able to obtain an integral equation for the renormalized
meson-baryon form factors in terms of the bare form factors as well as an
expression for the meson self energy. This integral equation is solved and
renormalized meson baryon form factors and renormalized baryon masses are
computed. The parameters of the model are adjusted to obtain a best fit to the
physical baryon masses. The calculations show that the renormalized form
factors are energy-dependent and differ from the bare form factors primarily at
momentum transfers smaller than 1 GeV. At nucleon mass, the change in the form
factors is about 10% at zero momentum transfer. The computed form factors are
soft with the equivalent monopole cut-off mass of about 500 MeV. The
renormalized coupling constants are obtained by comparing the chiral colour
dielectric model interaction Hamiltonian with the standard form of
meson-nucleon interaction Hamiltonian. The ratio of $\Delta N\pi$ and $NN\pi$
coupling constants is found to be about 2.15. This value is very close to the
experimental value.


title: On the origin of the radial flow in low energy heavy ion reactions

abstract:
  The average transverse energy of nucleons and intermediate mass fragments
observed in the heavy ion reaction Xe(50A MeV)+Sn shows the same linear
increase as a function of their mass as observed in heavy ion collisions up to
the highest ene rgies available today and fits well into the systematics. At
higher energies this observation has been interpreted as a sign of a strong
radial flow in an otherwise thermalized system. Investigating the reaction with
Quantum Molecular dynamics simulations we find in between 50A MeV and 200A MeV
a change in the reaction mechanism. At 50A MeV the apparent radial flow is
merely caused by an in-plane flow and Coulomb repulsion. The average transverse
fragment energy does not change in the course of the reaction and is equal to
the initial fragment energy due to the Fermi motion. At 200A MeV, there are two
kinds of fragments: those formed from spectator matte r and those from the
center of the reaction. There the transverse energy is caused by the pr essure
from the compressed nuclear matter. In both cases we observe a binary event
stru cture, even in central collisions. This demonstrates as well the non
thermal character of the reaction. The actual process which leads to
multifragmentation is rather complex and is discussed in detail.


title:
Chiral Dynamics of Low-Energy Kaon-Baryon Interactions with Explicit
  Resonance

abstract:
  The processes involving low energy $\bar{K}N$ and $Y\pi$ interactions (where
$Y= \Sigma$ or $\Lambda$) are studied in the framework of heavy baryon chiral
perturbation theory with the $\Lambda$(1405) resonance appearing as an
independent field.
  The leading and next-to-leading terms in the chiral expansion are taken into
account. We show that an approach which explicitly includes the $\Lambda$(1405)
resonance as an elementary quantum field gives reasonable descriptions of both
the threshold branching ratios and the energy dependence of total cross
sections.


title:
Strangeness Production in the HSD Transport Approach from SIS to SPS
  energies

abstract:
  We study systematically the production of strangeness in nuclear reactions
from SIS to SPS energies within the covariant hadronic transport approach HSD.
Whereas the proton and pion rapidity distributions as well as pion transverse
momentum spectra are well described in the hadronic transport model from 2-200
AGeV, the $K^+$ and $K^-$ spectra are noticeably underestimated at AGS energies
while the $K^+$ spectra match well at SIS and SPS energies with the
experimental data. We conclude that the failure of the hadronic model at AGS
energies points towards a nonhadronic phase during the collision of heavy
systems around 10 AGeV.


title:
Deduction of the quantum numbers of low-lying states of 6-nucleon
  systems based on symmetry

abstract:
  The inherent nodal structures of the wavefunctions of 6-nucleon systems have
been investigated. The existence of a group of six low-lying states dominated
by L=0 has been deduced. The spatial symmetries of these six states are found
to be mainly {4,2} and {2,2,2}.


title: Meson-Exchange Model for the YN Interaction

abstract:
  We report on progress in the development of a microscopic model for the
hyperon-nucleon interaction within the meson-exchange framework, which
incorporates both one-meson as well as correlated two-meson exchange
contributions. The main new feature of the model is the exchange of two
correlated pions or kaons, both in the scalar-isoscalar and the
vector-isovector channels. In the scalar channel it provides the main part of
the intermediate-range interaction between two baryons, thereby eliminating the
need for the fictitious sigma meson, which has been an unavoidable element of
effective one-boson-exchange descriptions.


title: Pairing and symmetry energy in N \simeq Z nuclei

abstract:
  It is shown that in N \simeq Z nuclei the effects of isovector pairing and
the symmetry energy are intimately related. In particular, in the odd-odd N = Z
nuclei these two effect are essentially equal in magnitude, causing near
degeneracy of the lowest T = 1 and T = 0 states and appearance of the T = 1
ground state isospin in many such nuclei. Following the earlier work of
Jaenecke, it is shown that the global symmetry energy fit can be reproduced
using just the excitation energies of the lowest T = 3/2 states in N = Z+1
nuclei. Similarly, the global pairing gap fit can be related to the excitation
energy of the T = |N - Z|/2 +1 states in N \simeq Z even A nuclei.


title: Fine-Tuning Two-Particle Interferometry II: Opacity Effects

abstract:
  We present a model study of single-particle spectra and two-particle
Bose-Einstein correlations for opaque sources. We study the transverse mass
dependence of the correlation radii R_\perp, R_\parallel and R_0 in the YKP
parametrization and find a strong sensitivity of the temporal radius parameter
R_0^2 to the source opacity. A simple comparison with the published data from
158 A GeV/c Pb+Pb collisions at CERN indicates that the pion source created in
these collisions emits particles from the whole reaction volume and is not
opaque. For opaque sources we find certain regions of inapplicability of the
YKP parametrization which can be avoided by a slightly different
parametrization for the correlator. The physical meaning of the modified
parameters is briefly discussed.


title: On the flow of kaons produced in relativistic heavy ion collisions

abstract:
  We investigate the different contributions to the in-plane flow of K+ mesons
observed recently by the FOPI collaboration in the reaction Ni(1.93 AGeV)+Ni.
Due to the kinematics of the three body phase space decay the flow of kaons
produced in baryon-baryon interactions is smaller than that of the baryons in
the entrance channel. On the contrary, in pi N interactions the flow of the
sources and of the kaons are identical. Therefore the total kaon flow depends
on the relative number of Delta N -> K+ and pi N -> K+ reactions and hence on
the lifetime of the Delta, in addition to the already known dependence on the
potential interaction interaction of the kaons with the nuclear environment.


title:
Three Body Bound State Calculations without Angular Momentum
  Decomposition

abstract:
  The Faddeev equations for the three body bound state are solved directly as
three dimensional integral equation without employing partial wave
decomposition. The numerical stability of the algorithm is demonstrated. The
three body binding energy is calculated for Malfliet-Tjon type potentials and
compared with results obtained from calculations based on partial wave
decomposition. The full three body wave function is calculated as function of
the vector Jacobi momenta. It is shown that it satisfies the Schr\"odinger
equation with high accuracy. The properties of the full wave function are
displayed and compared to the ones of the corresponding wave functions obtained
as finite sum of partial wave components. The agreement between the two
approaches is essentially perfect in all respects.


title:
Quark-meson coupling model with constituent quarks: Exchange and pionic
  effects

abstract:
  The binding energy of nuclear matter including exchange and pionic effects is
calculated in a quark-meson coupling model with massive constituent quarks. As
in the case with elementary nucleons in QHD, exchange effects are repulsive.
However, the coupling of the mesons directly to the quarks in the nucleons
introduces a new effect on the exchange energies that provides an extra
repulsive contribution to the binding energy. Pionic effects are not small.
Implications of such effects on observables are discussed.


title: Scattering states in the four nucleons system

abstract:
  The Faddeev-Yakubowski equations have been solved in configuration space for
the four nucleons system. Results for bound and scattering states in the
isospin and S-wave approximation for different (T,S) channels are presented.
The n-t elastic cross section has been also calculated with realistic
interactions. A special interest was devoted to the description of the observed
resonant structure at $T_{lab}\approx 3$ MeV which is well reproduced only by
the simple MT I-III potential.


title:
Antikaon Production in Proton-Nucleus Reactions and the $K^-$ properties
  in nuclear matter

abstract:
  We calculate the momentum-dependent potentials for $K^+$ and $K^-$ mesons in
a dispersion approach at nuclear density $\rho_0$ using the information from
the vacuum $K^+ N$ and $K^- N$ scattering amplitudes, however, leaving out the
resonance contributions for the in-medium analysis. Whereas the $K^+$ potential
is found to be repulsive ($\approx$ + 30 MeV) and to show only a moderate
momentum dependence, the $K^-$ selfenergy at normal nuclear matter density
turns out to be $\approx$ - 200 MeV at zero momentum in line with kaon atomic
data, however, decreases rapidly in magnitude for higher momenta. The antikaon
production in p + A reactions is calculated within a coupled transport approach
and compared to the data at KEK including different assumptions for the
antikaon potentials. Furthermore, detailed predictions are made for $p +
^{12}C$ and $p + ^{207}Pb$ reactions at 2.5 GeV in order to determine the
momentum dependent antikaon potential experimentally.


title: Coulomb effects on growth of instabilities in asymmetric nuclear matter

abstract:
  We study the effects of the Coulomb interaction on the growth of unstable
modes in asymmetric nuclear matter. In order to compare with previous
calculations we use a semiclassical approach based on the linearized Vlasov
equation. Moreover, a quantum calculation is performed within the R.P.A.. The
Coulomb effects are a slowing down of the growth and the occurrence of a
minimal wave vector for the onset of the instabilities. The quantum corrections
cause a further decrease of the growth rates.


title:
Omega meson as a chronometer and thermometer in hot-dense hadronic
  matter

abstract:
  Changes in the properties of the vector mesons in hot and dense hadronic
matter, as produced in heavy ion collisions, lead to the intriguing possibility
of the opening of the decay channel $\omega \ra \rho \pi$, for the omega meson,
which is impossible in free space. This along with the channel $\omega \pi \ra
\pi \pi$ would result in a decrease in its effective life-time enabling it to
decay within the hot zone and act as a chronometer in contradiction to the
commonly held opinion and would have implications vis a vis determination of
the size of the region through pion interferometry. A new peak and a radically
altered shape of the low invariant mass dilepton spectra appears due to
different shift in the masses of $\rho$ and $\omega$ mesons. The Walecka model
is used for the underlying calculation for the sake of illustration.


title: On QCD sum rules for vector mesons in nuclear medium

abstract:
  Vector mesons show up in the electromagnetic current-current correlator. QCD
sum rules provide a constraint on hadronic models for this correlator. This
constraint is discussed for the case of finite nuclear density concerning the
longitudinal as well as the transverse part of the current-current correlator
at finite three-momentum.


title: Heavy ion collisions with non-equilibrium Dirac-Brueckner mean fields

abstract:
  The influence of realistic interactions on the reaction dynamics in
intermediate energy heavy ion collisions is investigated. The mean field in
relativistic transport calculations is derived from microscopic Dirac-Brueckner
(DB) self-energies, taking non-equilibrium effects, in particular the
anisotropy of the local phase space configurations, into account. Thus this
approach goes beyond the local density approximation. A detailed analysis of
various in-plane and out-of-plane flow observables is presented for Au on Au
reactions at incident energies ranging from 250 to 800 A.MeV and the results
are compared to recent measurements of the FOPI collaboration. An overall good
agreement with in-plane flow data and a reasonable description of the
out-of-plane emission is achieved. For these results the intrinsic momentum
dependence of the non-equilibrium mean fields is important. On the other hand,
the local density approximation with the same underlying DB forces as well as a
standard non-linear version of the $\sigma\omega$ model are less successful in
describing the present data. This gives evidence of the applicability of self
energies derived from the DB approach to nuclear matter also far from
saturation and equilibrium.


title:
Backward Elastic p^3He-Scattering and High Momentum components of ^3He
  Wave Function

abstract:
  It is shown that owing to a dominance of $np-$pair transfer mechanism of
backward elastic $p^3He$- scattering for incident proton kinetic energies
$T_p>1$ GeV the cross section of this process is defined mainly by the values
of the Faddeev component of the wave function of $^3He$ nucleus, $\phi
^{23}({\bf q}_{23}, {\bf p}_1)$, at high relative momenta $q_{23}> 0.6 GeV/c$
of the NN-pair in the $^1S_0-$ state and at low spectator momenta $p_1\sim
0-0.2$ GeV/c.


title:
Spatial Variation of Nuclear Structure Functions and Heavy Quark
  Production

abstract:
  We explore how nuclear modifications to the free nucleon structure functions
(also known as shadowing) affect heavy quark production in collisions at
different impact parameters. We assume that the nuclear modifications arise
from a density dependent effect such as gluon recombination and are thus
proportional to the local density. We calculate the dependence of charm and
bottom quark production on impact parameter and show that density dependent
modifications can lead to significant reductions in the heavy quark production
cross sections in central relative to peripheral interactions.


title:
The Coulomb Interaction between Pion-Wavepackets: The piplus-piminus
  Puzzle

abstract:
  The time dependent Schr\"odinger equation for $\pi^+$--$\pi^-$ pairs, which
are emitted from the interaction zone in relativistic nuclear collisions, is
solved using wavepacket states. It is shown that the Coulomb enhancement in the
momentum correlation function of such pairs is smaller than obtained in earlier
calculations based on Coulomb distorted plane waves. These results suggest that
the experimentally observed positive correlation signal cannot be caused by the
Coulomb interaction between pions emitted from the interaction zone. But other
processes which involve long-lived resonances and the related extended source
dimensions could provide a possible explanation for the observed signal.


title: Resonance trapping and saturation of decay widths

abstract:
  Resonance trapping appears in open many-particle quantum systems at high
level density when the coupling to the continuum of decay channels reaches a
critical strength. Here a reorganization of the system takes place and a
separation of different time scales appears. We investigate it under the
influence of additional weakly coupled channels as well as by taking into
account the real part of the coupling term between system and continuum. We
observe a saturation of the mean width of the trapped states. Also the decay
rates saturate as a function of the coupling strength. The mechanism of the
saturation is studied in detail. In any case, the critical region of
reorganization is enlarged. When the transmission coefficients for the
different channels are different, the width distribution is broadened as
compared to a chi_K^2 distribution where K is the number of channels. Resonance
trapping takes place before the broad state overlaps regions beyond the
extension of the spectrum of the closed system.


title: Deep Potentials of the NN Interactions with Forbidden States

abstract:
  The three variant of the potentials with tensor part and ioao containing
unobservable forbidden states and having one fitted parameter are considered.
Parameter of such potentials is fixed only on the base low energy NN
characteristics and deuteron binding energies. The NN characteristics at high
energies, deuteron properties and formfactors up to 6 Fm-1 is appear in the
good consent with experimental data.


title:
Derivation of the Effective Pion-Nucleon Lagrangian within Heavy Baryon
  Chiral Perturbation Theory

abstract:
  We develop a method for constructing the Heavy Baryon Chiral Perturbation
Theory Lagrangian (L_{HBChPT}), to a given chiral order, within HBChPT. We work
within SU(2) theory, with only the pion field interacting with the nucleon. The
main difficulties, which are solved, are to develop techniques for implementing
charge conjugation invariance, and for taking the nucleon on shell, both within
the nonrelativistic formalism. We obtain complete lists of independent terms in
L_{HBChPT} through O(q^3) for off- shell nucleons. Then, eliminating
equation-of-motion (eom) terms at the relativistic and nonrelativistic level
(both within HBChPT), we obtain L_{HBCHPT} for on-shell nucleons, through
O(q^3). The extension of the method (to obtain on-shell L_{HBChPT} within
HBChPT) to higher orders is also discussed.


title: Hyperon properties in finite nuclei using realistic $YN$ interactions

abstract:
  Single-particle energies of the $\Lambda$ and $\Sigma$ hyperons are obtained
from the relevant self-energies. The latter are constructed within the
framework of a perturbative many-body approach employing present realistic
hyperon-nucleon interactions such as the models of the Juelich and Nijmegen
groups. The effects of the non-locality and energy dependence of the
self-energy on the bound states are investi- gated. It is also shown that,
although the single-particle hyperon energies are well reproduced by local
Woods-Saxon hyperon-nucleus potentials, the wave functions from the non-local
self-energy are far more extended. Implications of this behavior on the mesonic
weak decay of $\Lambda$ hypernuclei are discused.


title: Quantum Monte Carlo Studies of Relativistic Effects in Light Nuclei

abstract:
  Relativistic Hamiltonians are defined as the sum of relativistic one-body
kinetic energy, two- and three-body potentials and their boost corrections. In
this work we use the variational Monte Carlo method to study two kinds of
relativistic effects in the binding energy of 3H and 4He. The first is due to
the nonlocalities in the relativistic kinetic energy and relativistic one-pion
exchange potential (OPEP), and the second is from boost interaction. The OPEP
contribution is reduced by about 15% by the relativistic nonlocality, which may
also have significant effects on pion exchange currents. However, almost all of
this reduction is canceled by changes in the kinetic energy and other
interaction terms, and the total effect of the nonlocalities on the binding
energy is very small. The boost interactions, on the other hand, give repulsive
contributions of 0.4 (1.9) MeV in 3H (4He) and account for 37% of the
phenomenological part of the three-nucleon interaction needed in the
nonrelativistic Hamiltonians.


title: Isotopic and Microcanonical Temperatures in Nuclear Multifragmentation

abstract:
  A systematic comparison of different isotopic temperatures with the
thermodynamical temperature of a multifragment system is made on the basis of
the Statistical Multifragmentation Model. It is demonstrated that isotopic
temperatures are strongly affected by the secondary decays of hot primary
fragments and the population of particle-stable excited states in final
fragments. The He-Li temperatures, measured recently by the ALADIN group, are
reproduced fairly well both as a function of excitation energy and bound
charge. Our analysis confirms the anomaly in the nuclear caloric curve.


title:
Relativistic Equation of State of Nuclear Matter for Supernova and
  Neutron Star

abstract:
  We construct the equation of state (EOS) of nuclear matter using the
relativistic mean field (RMF) theory in the wide density, temperature range
with various proton fractions for the use of supernova simulation and the
neutron star calculations. We first construct the EOS of homogeneous nuclear
matter. We use then the Thomas-Fermi approximation to describe inhomogeneous
matter, where heavy nuclei are formed together with free nucleon gas. We
discuss the results on free energy, pressure and entropy in the wide range of
astrophysical interest. As an example, we apply the resulting EOS on the
neutron star properties by using the Oppenheimer-Volkoff equation.


title:
Unstable particles in matter at a finite temperature: the rho and omega
  mesons

abstract:
  Unstable particles (such as the vector mesons) have an important role to play
in low mass dilepton production resulting from heavy ion collisions and this
has been a subject of several investigations. Yet subtleties, such as the
implications of the generalization of the Breit-Wigner formula for nonzero
temperature and density, e.g. the question of collisional broadening, the role
of Bose enhancement, etc., the possibility of the kinematic opening (or
closing) of decay channels due to environmental effects, the problem of double
counting through resonant and direct contributions, are often given
insufficient emphasis. The present study attempts to point out these features
using the rho and omega mesons as illustrative examples. The difference between
the two versions of the Vector Meson Dominance Model in the present context is
also presented. Effects of non-zero temperature and density, through vector
meson masses and decay widths, on dilepton spectra are studied, for
concreteness within the framework of a Walecka-type model, though most of the
basic issues highlighted apply to other scenarios as well.


title: Deconfinement in the Quark Meson Coupling Model

abstract:
  The Quark Meson Coupling Model which describes nuclear matter as a collection
of non-overlapping MIT bags interacting by the self-consistent exchange of
scalar and vector mesons is used to study nuclear matter at finite temperature.
In its modified version, the density dependence of the bag constant is
introduced by a direct coupling between the bag constant and the scalar mean
field. In the present work, the coupling of the scalar mean field with the
constituent quarks is considered exactly through the solution of the Dirac
equation. Our results show that a phase transition takes place at a critical
temperature around 200 MeV in which the scalar mean field takes a nonzero value
at zero baryon density. Furthermore it is found that the bag constant decreases
significantly when the temperature increases above this critical temperature
indicating the onset of quark deconfinement.


title:
Self consistent random phase approximation within the O(5) model and
  Fermi transitions

abstract:
  Self Consistent Quasiparticle Random Phase Approximation (SCQRPA) is
considered in application to the Fermi transitions within the O(5) model. It is
demonstrated that SCQRPA improves on renormalized QRPA (RQRPA), a method that
has recently become rather popular in this context. The analytical form of the
SCQRPA vacuum is used to evaluate all the matrix elements. The SCQRPA results
show a general trend similar to the exact solutions. The necessity to change
the single particle basis beyond the transition point, and to include the
proton-proton and neutron-neutron channels in the QRPA operator, in addition to
the proton-neutron one, is pointed out.


title:
An exactly solvable model of a superconducting to rotational phase
  transition

abstract:
  We consider a many-fermion model which exhibits a transition from a
superconducting to a rotational phase with variation of a parameter in its
Hamiltonian. The model has analytical solutions in its two limits due to the
presence of dynamical symmetries. However, the symmetries are basically
incompatible with one another; no simple solution exists in intermediate
situations. Exact (numerical) solutions are possible and enable one to study
the behavior of competing but incompatible symmetries and the phase transitions
that result in a semirealistic situation. The results are remarkably simple and
shed light on the nature of phase transitions.


title: Sudden To Adiabatic Transition in Beta Decay

abstract:
  We discuss effects in beta decays at very low beta energies, of the order of
the kinetic energies of atomic electrons. As the beta energy is lowered the
atomic response changes from sudden to adiabatic. As a consequence, the beta
decay rate increases slightly and the ejection of atomic electrons (shake off)
and subsequent production of X rays is turned off. We estimate the transition
energy and the change in decay rate. The rate increase is largest in heavy
atoms, which have a small Q value in their decay. The X ray switch-off is
independent of Q value.


title: Self-consistency in the Projected Shell Model

abstract:
  The Projected Shell Model is a shell model theory built up over a deformed
BCS mean field. Ground state and excited bands in even-even nuclei are obtained
through diagonalization of a pairing plus quadrupole Hamiltonian in an angular
momentum projected 0-, 2-, and 4-quasiparticle basis. The residual
quadrupole-quadrupole interaction strength is fixed self-consistently with the
deformed mean field and the pairing constants are the same used in constructing
the quasiparticle basis. Taking $^{160}Dy$ as an example, we calculate
low-lying states and compare them with experimental data. We exhibit the effect
of changing the residual interaction strengths on the spectra. It is clearly
seen that there are many $J^\pi = 0^+, 1^+, 4^+$ bandheads whose energies can
only be reproduced using the self-consistent strengths. It is thus concluded
that the Projected Shell Model is a model essentially with no free parameters.


title:
Microscopic model analyses of the elastic scattering of 65 MeV protons
  from targets of diverse mass

abstract:
  Nonlocal coordinate space optical potentials for the scattering of 65 MeV
protons from nuclei ranging in mass from 6Li to 238U have been defined by
folding a complex, medium dependent effective interaction with the density
matrix elements of each target. The effective interaction is based upon
solutions of the Lippmann--Schwinger and Brueckner--Bethe--Goldstone equations
having the Paris potential as input. The nuclear structure information required
in our folding model are the one body density matrix elements for the target
and the single nucleon bound state wave functions that they weight. For light
mass nuclei, very large basis shell model calculations have been made to obtain
the one body density matrix elements. For medium and heavy mass nuclei, a very
simple shell model prescription has been used. The bound state single particle
wave functions that complete the nuclear density matrices are either
Woods--Saxon or harmonic oscillator functions. The former are employed in most
cases when large basis structure is available. For light nuclei (A < 16)
Woods--Saxon potential parameters and harmonic oscillator lengths are
determined from fits to electron scattering form factors. For all other nuclei,
we use harmonic oscillator functions with the oscillator lengths set from an
A^{1/6} mass law. Using this microscopic model, optical potentials result from
which differential cross sections, analyzing powers and spin rotations are
found. In general the calculated results compare very well with data when the
effective interactions are determined from a mapping of nucleon--nucleon g
matrices. This is not the case when effective interactions built from a mapping
of (free) t matrices are used.


title:
Effects of finite width of excited states on heavy-ion sub-barrier
  fusion reactions

abstract:
  We discuss the effects of coupling of the relative motion to nuclear
collective excitations which have a finite lifetime on heavy-ion fusion
reactions at energies near and below the Coulomb barrier. Both spreading and
escape widths are explicitly taken into account in the exit doorway model. The
coupled-channels equations are numerically solved to show that the finite
resonance width always hinders fusion cross sections at subbarrier energies
irrespective of the relative importance between the spreading and the escape
widths. We also show that the structure of fusion barrier distribution is
smeared due to the spreading of the strength of the doorway state.


title:
Collective quadrupole excitations in the 50<Z,N<82 nuclei with the
  generalized Bohr Hamiltonian

abstract:
  The generalized Bohr Hamiltonian is applied to a description of low-lying
collective excitations in even-even isotopes of Te, Xe, Ba, Ce, Nd and Sm. The
collective potential and inertial functions are determined by means of the
Strutinsky method and the cranking model, respectively. A shell-dependent
parametrization of the Nilsson potential is used. An approximate
particle-number projection is performed in treatment of pairing correlations.
The effect of coupling with the pairing vibrations is taken into account
approximately when determining the inertial functions. The calculation does not
contain any free parameter.


title: Structure Effects on Coulomb Dissociation of $^8$B

abstract:
  Coulomb Dissociation provides an alternative method for determining the
radiative capture cross sections at astrophysically relevant low relative
energies. For the breakup of $^8$B on $^{58}$Ni, we calculate the total Coulomb
Dissociation cross section and the angular distribution for E1, E2 and M1. Our
calculations are performed first within the standard first order semiclassical
theory of Coulomb Excitation, including the correct three body kinematics, and
later including the projectile-target nuclear interactions.


title:
Multi-boson effects and the normalization of the two-pion correlation
  function

abstract:
  The two-pion correlation function can be defined as a ratio of either the
measured momentum distributions or the normalized momentum space probabilities.
We show that the first alternative avoids certain ambiguities since then the
normalization of the two-pion correlator contains important information on the
multiplicity distribution of the event ensemble which is lost in the second
alternative. We illustrate this explicitly for specific classes of event
ensembles.


title:
Solution of relativistic Hartree-Bogoliubov equations in configurational
  representation: spherical neutron halo nuclei

abstract:
  The scaled harmonic oscillator basis (SHO) is derived by a local
scaling-point transformation of the spherical harmonic oscillator radial wave
functions. The unitary scaling transformation produces a basis with improved
asymptotic properties. The SHO basis is employed in the solution of the
relativistic Hartree-Bogoliubov (RHB) equations in configurational space. The
model is applied in the self-consistent mean-field approximation to the
description of the neutron halo in Ne isotopes. It is shown that an expansion
of nucleon spinors and mean-field potentials in the SHO basis reproduces the
asymptotic properties of neutron densities calculated by finite element
discretization in the coordinate space. In the RHB description of neutron skins
and halos, SHO bases in two or three dimensions can be a useful alternative to
technically complicated solutions on a mesh in coordinate space.


title: Electromagnetic Structure of the Trinucleons

abstract:
  The electromagnetic form factors of the trinucleons 3H and 3He are calculated
with wave functions obtained with the Argonne AV18 two-nucleon and Urbana IX
three-nucleon interactions. Full account is taken of the two-body currents
required by current conservation with the AV18 interaction as well as those
associated with N-Delta transition currents and the currents of Delta resonance
components in the wave functions. Explicit three-nucleon current operators
associated with the two-pion exchange three-nucleon interaction arising from
irreducible S-wave pion-nucleon scattering is constructed and shown to have
very little effect on the calculated magnetic form factors. The calculated
magnetic form factor of 3H, and charge form factors of both 3H and 3He are in
satisfactory agreement with the experimental data. However, the position of the
zero in the magnetic form factor of 3He is slightly underpredicted.


title:
Large Shell Model Calculations for Calcium Isotopes: Spectral Statistics
  and Chaos

abstract:
  We perform large shell model calculations for Calcium isotopes in the full fp
shell by using the realistic Kuo-Brown interaction. The Calcium isotopes are
especially interesting because the nearest-neighbour spacing distribution P(s)
of low-lying energy levels shows significant deviations from the predictions of
the Gaussian Orthogonal Ensemble of random--matrix theory. This contrasts with
other neighbouring nuclei which show fully chaotic spectral distributions. We
study the chaotic behaviour as a function of the excitation energy. In
addition, a clear signature of chaos suppression is obtained when the
single-particle spacings are increased. In our opinion the relatively weak
strength of the neutron-neutron interaction is unable to destroy the regular
single-particle mean-field motion completely. In the neighbouring nuclei with
both protons and neutrons in valence orbits, on the other hand, the stronger
proton-neutron interaction would appear to be sufficient to destroy the regular
mean-field motion.


title:
Collisional Damping of Nuclear Collective Vibrations in a Non-Markovian
  Transport Approach

abstract:
  A detailed derivation of the collisional widths of collective vibrations is
presented in both quantal and semi-classical frameworks by considering the
linearized limits of the extended TDHF and the BUU model with a non-Markovian
binary collision term. Damping widths of giant dipole and giant quadrupole
excitations are calculated by employing an effective Skyrme force, and the
results are compared with GDR measurements in Lead and Tin nuclei at finite
temperature.


title: New Discrete Basis for Nuclear Structure Studies

abstract:
  A complete discrete set of spherical single-particle wave functions for
studies of weakly-bound many-body systems is proposed. The new basis is
obtained by means of a local-scale point transformation of the spherical
harmonic oscillator wave functions. Unlike the harmonic oscillator states, the
new wave functions decay exponentially at large distances. Using the new basis,
characteristics of weakly-bound orbitals are analyzed and the ground state
properties of some spherical doubly-magic nuclei are studied. The basis of the
transformed harmonic oscillator is a significant improvement over the harmonic
oscillator basis, especially in studies of exotic nuclei where the coupling to
the particle continuum is important.


title:
Intermediate-mass dilepton production in heavy-ion collisions at 200A
  GeV

abstract:
  Through the analysis of HELIOS-3 data obtained at the CERN SPS, we
demonstrate the importance of secondary processes for dilepton production in
heavy-ion collisions in the intermediate invariant mass region. We find that
while the dilepton spectra between 1 to 2.5 GeV from proton-induced reactions
can be attributed to the decay of primary vector mesons, charmed hadrons, and
initial Drell-Yan processes; the strong enhancement seen in the heavy-ion data
as compared to the background comes mainly from the secondary processes which
are germane to heavy-ion collisions. Furthermore, we find $\pi a_1\to l{\bar
l}$ to be the most important process in this mass region, as was found by
thermal rate calculations. We emphasize the constraints on the elementary cross
sections by the experimental data from $e^+e^-$ annihilation.


title: g-factor of a tightly bound electron

abstract:
  We study the hyperfine splitting of an electron in hydrogen-like $^{209}Bi
^{82+} $. It is found that the hfs energy splitting can be explained well by
considering the g-factor reduction due to the binding effect of a bound
electron. We determine for the first time the experimental value of the
magnetic moment of a tightly bound electron.


title:
Octet and Decuplet Baryons in a Covariant and Confining Diquark-Quark
  Model

abstract:
  The baryon octet and decuplet masses and Bethe-Salpeter vertex and wave
functions are calculated in the ladder approximation to the quark exchange
between a scalar or axialvector diquark and a constituent quark. These
functions reflecting full Lorentz covariance are given in terms of an expansion
in Gegenbauer polynomials. In the rest frame of the baryon, a complete partial
wave decomposition of the Bethe-Salpeter wave function is performed. The
confinement of quarks and diquarks is implemented via a parametrisation of the
corresponding propagators. We also discuss some aspects of the momentum routing
in the ladder approximation to the Bethe-Salpeter equation. Numerical results
for the octet and decuplet masses with broken flavour SU(3) in the conserved
isospin limit are presented.


title: Heavy ion beam lifetimes at relativistic and ultrarelativistic colliders

abstract:
  The effects of higher order corrections in ultra-relativistic nuclear
collisions are considered. It is found that higher order contributions are
small at low energy, large at intermediate energy and small again at very high
energy. An explanation for this effect is given. This means that the
Weizsacker-Williams formula is a good approximation to use in calculating cross
sections and beam lifetimes at energies relevant to RHIC and LHC.


title:
The astrophysical reaction 8Li(n,gamma)9Li from measurements by reverse
  kinematics

abstract:
  We study the breakup of 9Li projectiles in high energy (28.5 MeV/u)
collisions with heavy nuclear targets (208Pb). The wave functions are
calculated using a single-particle model for 9Li, and a simple optical
potential model for the scattering part. A good agreement with measured data is
obtained with insignificant E2 contribution.


title: Baryon resonances in a chiral confining model (I)

abstract:
  In this two part series a chiral confining model of baryons is used to
describe low--lying negative parity resonances $N^*$, $\Delta^*$, $\Lambda^*$
and $\Sigma^*$ in the mean field approximation. A physical baryon in this model
consists of interacting valence quarks, mesons and a color and chiral singlet
hybrid field coexisting inside a dynamically generated confining region. This
first paper presents the quark contribution to the masses and wave functions of
negative parity baryons calculated with an effective spin--isospin dependent
instanton induced interaction. It does not include meson exchanges between
quarks. The three--quark wave functions are used to calculate meson--excited
baryon vertex functions to lowest order in meson--quark coupling. When the
baryons are on mass--shell each of these vertex functions is a product of a
coupling constant and a form factor. As examples, quark contributions to $N^*$
hadronic form factors as well as axial coupling constants are extracted from
the vertex functions and problems with the analytical behaviour of the model
form factors are discussed. The second paper will examine the mesonic
corrections to excited baryon properties in the heavy baryon and one--loop
approximations.


title: Dominance of Nuclear Processes in the Dissociation of 8B

abstract:
  We study the break-up of 8B in collisions with heavy-ions. The process is
described in terms of inelastic excitations leading to states in the continuum.
  The effects of the nuclear and coulomb fields are included on the same
footing in the microscopic construction of the transition matrix elements. The
interplay between coulomb and nuclear excitation processes differs
significantly from the situation encountered in reactions involving systems
close to the stability line. In particular, nuclear excitation is found to
remain predominant at energies well below the coulomb barrier,


title: Collective dynamics in highly relativistic heavy-ion collisions

abstract:
  Hydrodynamics with cylindrical symmetry in transverse direction and
longitudinal scaling flow is employed to calculate the transverse momentum
spectra of various hadrons and clusters (e.g. pi, K, N, Phi, Lambda, d, He) in
central heavy-ion collisions at CERN-SPS and BNL-RHIC energies up to pT=4 GeV.
We discuss the sensitivity of these spectra with respect to the initial
transverse density profile as well as to the choice of ``freeze-out''
hypersurface. For SPS energy and pT<2 GeV, overall good agreement of the pT
distributions with data is found when freeze-out occurs along the T=130 MeV
isotherm. Even high-pT neutral pion data can be described for a particular
choice of the initial transverse density profile. It is shown that the average
transverse velocity <vT> of heavy hadrons and hadronic clusters is a good
measure for the collective flow velocity. The latter is found to be rather
similar for SPS and RHIC energies, due to the ``stall'' of the flow within the
long-lived mixed phase at RHIC. In case of thermalization and hydrodynamical
expansion, the mean transverse momentum <pT> increases linearly with the hadron
mass. In contrast, the string model FRITIOF7.02, which does not account for
rescattering of secondary hadrons, predicts a strong dependence of <pT> on the
quark composition of the hadron. Due to the different sensitivity to hard
processes, hadrons with charm (anti-)quarks acquire significantly more
transverse momentum than hadrons without c (or even without s) quarks.


title: Freeze out in hydrodynamical models

abstract:
  We study the effects of strict conservation laws and the problem of negative
contributions to final momentum distribution during the freeze out through
3-dimensional hypersurfaces with space-like normal. We study some suggested
solutions for this problem, and demonstrate it on one example.


title:
QCD bound states and their response to extremes of temperature and
  density

abstract:
  We describe the application of Dyson-Schwinger equations to the calculation
of hadron observables. The studies at zero temperature (T) and quark chemical
potential (mu) provide a springboard for the extension to finite-(T,mu). Our
exemplars highlight that much of hadronic physics can be understood as simply a
manifestation of the nonperturbative, momentum-dependent dressing of the
elementary Schwinger functions in QCD.


title: Anti-Lambda/Anti-Proton ratios at the AGS

abstract:
  We attempt to explain the large ${\bar \Lambda}/\bar p$ ratios measured in
heavy ion collisions at $12~{\rm A\cdot GeV}/c$ beam momentum within an
hadronic framework. The ratios are large compared to corresponding ratios in
$pp$ collisions, and to thermal fits. We show using a simple model and a
detailed cascade calculation 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. Uncertainties in elementary
cross--sections and formation times are also considered.


title:
Liquid-gas phase transition in finite nuclei within Fermionic Molecular
  Dynamics

abstract:
  Within Fermionic Molecular Dynamics (FMD) a quantal nuclear system with only
16 nucleons shows a clearly visible liquid-gas phase transition. The FMD model
is an approximation to the many-body problem which describes the system by
antisymmetrized many-body states in which each nucleon is occupying a Gaussian
shaped time-dependent wave-packet. The statistical ensemble is obtained by time
averaging.


title: Baryon Number Transport via Gluonic Junctions

abstract:
  A novel non-perturbative gluon junction mechanism is introduced within the
HIJING/B nuclear collision event generator to calculate baryon number transport
and hyperon production in pA and AA collisions. This gluonic mechanism can
account for the observed large mid-rapidity valence baryon yield in Pb+Pb at
160 AGeV and predicts high initial baryon densities at RHIC. However, the
highly enhanced Lambda-Lambdabar yield and the baryon transverse momentum flow
observed in this reaction can only be partially described.


title: Relativistic Mean Field Approach and the Pseudo-Spin Symmetry

abstract:
  Based on the Relativistic Mean Field (RMF) approach the existence of the
broken pseudo-spin symmetry is investigated. Both spherical RMF and constrained
deformed RMF calculations are carried out employing realistic Lagrangian
parameters for spherical and for deformed sample nuclei. The quasi - degenerate
pseudo-spin doublets are confirmed to exist near the fermi surface for both
spherical and deformed nuclei.


title:
Entropy Production in Collisions of Relativistic Heavy Ions -- a signal
  for Quark-Gluon Plasma phase transition?

abstract:
  Entropy production in the compression stage of heavy ion collisions is
discussed within three distinct macroscopic models (i.e. generalized RHTA,
geometrical overlap model and three-fluid hydrodynamics). We find that within
these models \sim 80% or more of the experimentally observed final-state
entropy is created in the early stage. It is thus likely followed by a nearly
isentropic expansion. We employ an equation of state with a first-order phase
transition. For low net baryon density, the entropy density exhibits a jump at
the phase boundary. However, the excitation function of the specific entropy
per net baryon, S/A, does not reflect this jump. This is due to the fact that
for final states (of the compression) in the mixed phase, the baryon density
\rho_B increases with \sqrt{s}, but not the temperature T. Calculations within
the three-fluid model show that a large fraction of the entropy is produced by
nuclear shockwaves in the projectile and target. With increasing beam energy,
this fraction of S/A decreases. At \sqrt{s}=20 AGeV it is on the order of the
entropy of the newly produced particles around midrapidity. Hadron ratios are
calculated for the entropy values produced initially at beam energies from 2 to
200 AGeV.


title:
Mesons as qbar-q Bound States from Euclidean 2-Point Correlators in the
  Bethe-Salpeter Approach

abstract:
  We investigate the 2-point correlation function for the vector current. The
gluons provide dressings for both the quark self energy as well as the vector
vertex function, which are described consistently by the rainbow
Dyson-Schwinger equation and the inhomogeneous ladder Bethe-Salpeter equation.
The form of the gluon propagator at low momenta is modeled by a 2-parameter
ansatz fitting the weak pion decay constant. The quarks are confined in the
sense that the quark propagator does not have a pole at timelike momenta. We
determine the ground state mass in the vector channel from the Euclidean time
Fourier transform of the correlator, which has an exponential falloff at large
times. The ground state mass lies around 590 MeV and is almost independent of
the model form for the gluon propagator. This method allows us to stay in
Euclidean space and to avoid analytic continuation of the quark or gluon
propagators into the timelike region.


title:
Formation of $\eta$-mesic Nuclei Using the Recoilless (d,$^3$He)
  Reaction

abstract:
  We propose to use the recoilless (d,$^3$He) reaction to produce $\eta$-mesic
nuclei. This reaction has been used to observe deeply bound pionic states and
proven to be powerful recently. We calculate $\eta$-mesic bound states in the
nucleus using an optical potential and their formation cross section with the
Green function method. Then, we carefully check the experimental feasibility.
We find that $\eta$-mesic nuclei can be observed experimentally using the
(d,$^3$He) reaction. We also mention the possibility to study the formation of
$\omega$-mesic nuclei.


title:
Novel approach to pion and eta production in proton-proton collisions
  near threshold

abstract:
  We evaluate the threshold matrix-element for the reaction $pp \to pp\pi^0$ in
a fully relativistic Feynman diagrammatic approach. We employ a simple
effective range approximation to take care of the S-wave $pp$ final-state
interaction. The experimental value for the threshold amplitude ${\cal A} =
(2.7 - i 0.3)$ fm$^4$ can be reproduced by contributions from tree level chiral
(long-range) pion exchange and short-range effects related to vector meson
exchanges, with $\omega$ exchange giving the largest individual contribution.
Pion loop effects appear to be small. We stress that the commonly used heavy
baryon formalism is not applicable in the NN-system above the pion production
threshold due to the large external momentum, $|\vec p | \simeq \sqrt
{Mm_\pi}$, with $M$ and $m_\pi$ the nucleon and the pion mass, respectively. We
furthermore investigate the reaction $pp\to p n \pi^+$ near threshold within
the same approach. We extract from the data the triplet threshold amplitude as
${\cal B}= (2.8 -i 1.5)$ fm$^4$. Its real part can be well understood from
(relativistic) tree level meson-exchange diagrams. In addition, we investigate
the process $pp \to pp \eta$ near threshold. We use a simple factorization
ansatz for the $pp\eta$ final-state interaction and extract from the data the
modulus of the threshold amplitude, $|{\cal C}| = 1.32 $fm$^4$. With $g_{\eta
N}=5.3$, this value can be reproduced by (relativistic) tree level
meson-exchange diagrams and $\eta$-rescattering, whose strength is fixed by the
$\eta N$ scattering length. We also comment on the recent near threshold data
for $\eta'$-production.


title:
Relativistic Effects in Electromagnetic Meson-Exchange Currents for
  One-Particle Emission Reactions

abstract:
  Following recent studies of non-relativistic reductions of the single-nucleon
electromagnetic current operator, here we extend the treatment to include meson
exchange current operators. We focus on one-particle emission electronuclear
reactions. In contrast to the traditional scheme where approximations are made
for the transferred momentum, transferred energy and momenta of the
initial-state struck nucleons, we treat the problem exactly for the transferred
energy and momentum, thus obtaining new current operators which retain
important aspects of relativity not taken into account in the traditional
non-relativistic reductions. We calculate the matrix elements of our current
operators between the Fermi sphere and a particle-hole state for several
choices of kinematics. We present a comparison between our results using
approximate current operators and those obtained using the fully-relativistic
operators, as well as with results obtained using the traditional
non-relativistic current operators.


title:
Chaotic wave functions and exponential convergence of low-lying energy
  eigenvalues

abstract:
  We suggest that low-lying eigenvalues of realistic quantum many-body
hamiltonians, given, as in the nuclear shell model, by large matrices, can be
calculated, instead of the full diagonalization, by the diagonalization of
small truncated matrices with the exponential extrapolation of the results. We
show numerical data confirming this conjecture. We argue that the exponential
convergence in an appropriate basis may be a generic feature of complicated
("chaotic") systems where the wave functions are localized in this basis.


title: Consistent BCS+RQRPA formalism with application to the double beta decay

abstract:
  A new consistent analysis of the renormalized proton--neutron quasiparticle
random phase approximation based on the simultaneous recalculation of the
one--body density matrix and the pairing tensor has been used to study the
double beta decay. We demonstrated that inclusion of the quasiparticle
correlations at the BCS level reduces the ground state correlations in the
particle--particle channel of the proton--neutron interaction. We also
simplified the RQRPA equations significantly obtaining a low--dimensioned set
of linear equations for the quasiparticle densities. The formalism was applied
to the double beta decay in ^{76}Ge.


title: On Complete Sets of Polarization Observables

abstract:
  A new criterion is developed which provides a check as to whether a chosen
set of polarization observables is complete with respect to the determination
of all independent $T$-matrix elements of a reaction of the type $a+b\to
c+d+...$. As an illustrative example, this criterion is applied to the
longitudinal observables of deuteron electrodisintegration.


title: Thermonuclear Reaction Rate of 23Mg(p,gamma)24$Al

abstract:
  Updated stellar rates for the reaction 23Mg(p,gamma)24Al are calculated by
using all available experimental information on 24Al excitation energies.
Proton and gamma-ray partial widths for astrophysically important resonances
are derived from shell model calculations. Correspondences of experimentally
observed 24Al levels with shell model states are based on application of the
isobaric multiplet mass equation. Our new rates suggest that the
23Mg(p,gamma)24Al reaction influences the nucleosynthesis in the mass A>20
region during thermonuclear runaways on massive white dwarfs.


title: Proton drip-line nuclei in relativistic mean-field theory

abstract:
  The position of the two-proton drip line has been calculated for even-even
nuclei with $10 \leq Z \leq 82$ in the framework of the relativistic mean-field
(RMF) theory. The current model uses the NL3 effective interaction in the
mean-field Lagrangian and describes pairing correlations in the
Bardeen-Cooper-Schrieffer (BCS) formalism. The predictions of the RMF theory
are compared with those of the Hartree-Fock+BCS approach (with effective force
Skyrme SIII) and the finite-range droplet model (FRDM) and with the available
experimental information.


title: Alternative Linear Chiral Models for Nuclear Matter

abstract:
  The equation of state of a family of alternative linear chiral models in the
mean field approximation is discussed. We investigate the analogy between some
of these models with current models in the literature, and we show that it is
possible to reproduce very well the saturation properties of nuclear matter.


title: Relativistic transport theory for $N$, $\Delta$ and $N^{*}$(1440) system

abstract:
  A self-consistent relativistic Boltzmann-Uehling-Uhlenbeck equation for the
$N^{*}$(1440) resonance is developed based on an effective Lagrangian of
baryons interacting through mesons.
  The equation is consistent with that of nucleon's and delta's which we
derived before. Thus, we obtain a set of coupled equations for the $N$,
$\Delta$ and $N^{*}$(1440) distribution functions.
  All the $N^{*}$(1440)-relevant in-medium two-body scattering cross sections
within the $N$, $\Delta$ and $N^{*}$(1440) system are derived from the same
effective Lagrangian in addition to the mean field and presented analytically.
Medium effects on the cross sections are discussed.


title: $\eta^{\prime}$ Production in Proton-Proton Collisions near Threshold

abstract:
  Within the one-pion exchange model we calculate the near-threshold
${\eta}^{\prime}$ production from $pp$ collisions including the final state
interaction between the protons. Since the description of the data is quite
well we conclude that $\eta, \rho$ or $ \omega$ exchange currents either play
no role or cancel each other to a large extent in this reaction.


title: Charmonium Production in Nucleus-Nucleus Collisions

abstract:
  This is a review of theoretical attempts to describe production of heavy
quark bound states in nucleus-nucleus collisions, in particular, the relative
suppression of $J/\psi$ and $\psi'$ production observed in these reactions. The
review begins with a survey of experimental data for proton-induced reactions
and their theoretical interpretation. The evidence for additional suppression
in nucleus-nucleus collisions is discussed and various theoretical models of
charmonium absorption by comoving matter are presented and analyzed. The review
concludes with suggestions for future research that would help clarify the
implications of $J/\psi$ suppression in Pb + Pb collisions observed by the NA50
experiment.