title: Damping rates of hot Giant Dipole Resonances

abstract:
  The damping rate of hot giant dipole resonances (GDR) is investigated.
Besides Landau damping we consider collisions and density fluctuations as
contributions to the damping of GDR. Within the nonequilibrium Green's function
method we derive a non-Markovian kinetic equation. The linearization of the
latter one leads to complex dispersion relations. The complex solution provides
the centroid energy and the damping width of giant resonances. The experimental
damping widths are the full width half maximum (FWHM) and can be reproduced by
the full width of the structure function. Within simple finite size scaling we
give a relation between the minimal interaction strength which is required for
a collective oscillation and the clustersize. We investigate the damping of
giant dipole resonances within a Skyrme type of interaction. Different
collision integrals are compared with each other in order to incorporate
correlations. The inclusion of a conserving relaxation time approximation
allows to find the $T^2$-dependence of the damping rate with a temperature
known from the Fermi-liquid theory. However, memory effects turn out to be
essential for a proper treatment of the damping of collective modes. We derive
a Landau like formula for the one--particle relaxation time similar to the
damping of zero sound.


title: The nucleon wave function in light-front dynamics

abstract:
  The general spin structure of the relativistic nucleon wave function in the
$3q$-model is found. It contains 16 spin components, in contrast to 8 ones
known previously, since in a many-body system the parity conservation does not
reduce the number of the components. The explicitly covariant form of the wave
function automatically takes into account the relativistic spin rotations,
without introducing any Melosh rotation matrices. It also reduces the
calculations to the standard routine of the Dirac matrices and of the trace
techniques. In examples of the proton magnetic moment and of the axial nucleon
form factor, with a particular wave function, we reproduce the results of the
standard approach. Calculations beyond the standard assumptions give different
results.


title: A study of nuclei of astrophysical interest in the continuum shell model

abstract:
  We present here the first application of realistic shell model (SM) including
coupling between many-particle (quasi-)bound states and the continuum of
one-particle scattering states to the spectroscopy of 8B and to the calculation
of astrophysical factors in the reaction 7Be(p,gamma)8B.


title: Neutron star properties with nuclear BHF equations of state

abstract:
  We study the properties of static and rotating neutron stars adopting
non-relativistic equations of state (EOS) for asymmetric nuclear matter based
on the Brueckner-Hartree-Fock (BHF) scheme. The BHF calculation, with the
continuous choice for the single particle potential, appears to be very close
to the full EOS, which includes the three-hole line contribution calculated by
solving the Bethe-Fadeev equations within the gap choice for the single
particle potential. Three-body forces are included in order to reproduce the
correct saturation point for nuclear matter. A comparison with fully
relativistic many-body calculations of nuclear matter EOS is made.


title: Partonic Picture of Nuclear Shadowing at Small x

abstract:
  We find that coherent multiple scatterings of the partonic fluctuations of
the virtual photon with the nucleons inside the nucleus result in the large
nuclear shadowing effect for parton distributions in nuclei. We predict the
gluon shadowing effect at small $x$ and for $Q^2\geq 3 GeV^2$.


title: Effective Theory for Neutron-Deuteron Scattering: Energy Dependence

abstract:
  We report on results of the effective theory method applied to
neutron-deuteron scattering. We extend previous results in the $J=3/2$ channel
to non-zero energies and find very good agreement with experiment without any
parameter fitting.


title:
A new Perspective on the Scalar meson Puzzle, from Spontaneous Chiral
  Symmetry Breaking Beyond BCS

abstract:
  We introduce coupled channels of Bethe-Salpeter mesons both in the boundstate
equation for mesons and in the mass gap equation for chiral symmetry.
Consistency is insured by the Ward Identities for axial currents, which
preserve the Goldstone boson nature of the pion and prevents a systematic shift
of the hadron spectrum. We study the decay of a scalar meson coupled to a pair
of pseudoscalars. We also show that coupled channels reduce the breaking of
chiral symmetry, with the same Feynman diagrams that appear in the coupling of
a scalar meson to a pair of pseudoscalar mesons. Exact calculations are
performed in a particular confining quark model, where we find that the
groundstate $I=0, ^3P_0 q \bar q$ meson is the f_0(980) with a partial decay
width of 40MeV. We also find a 30% reduction of the chiral condensate due to
coupled channels.


title:
Inclusive Neutrino Scattering in C-12: Implications for nu_mu to nu_e
  Oscillations

abstract:
  We study inclusive nu_e and nu_mu cross sections in C-12 in a theory that
takes into account significant nuclear renormalization of strengths. Our
calculation is in excellent agreement with the measured inclusive muon capture
rate and the flux-averaged nu_e cross section, but overestimates the
flux-averaged nu_mu inclusive cross section. These reactions are of crucial
relevance to the issue of possible nu_mu to nu_e oscillations.We also calculate
the flux-averaged cross sections in C-13 and Al-27, which are found to be
consistent with the available experimental result.


title: Inclusive Muon Capture in Light Nuclei

abstract:
  We study total muon capture rates in light nuclei, taking into account
renormalizations of the nuclear vector and axial vector strengths. We estimate
the influence in the results of uncertainties of the spin-isospin interaction
parameter and nuclear densities. A few of these reactions are theoretical
benchmarks for physics involving searches for neutrino oscillations. New
experiments in muon capture in several targets are suggested, in the light of
some discrepancies with theory, crudeness of some experimental results and
relevance to neutrino physics.


title:
Pion-Nucleus Scattering at Medium Energies with Densities from Chiral
  Effective Field Theories

abstract:
  Recently developed chiral effective field theory models provide excellent
descriptions of the bulk characteristics of finite nuclei, but have not been
tested with other observables. In this work, densities from both relativistic
point-coupling models and mean-field meson models are used in the analysis of
meson-nucleus scattering at medium energies. Elastic scattering observables for
790
  MeV/$c$ $\pi^{\pm}$ on $^{208}$Pb are calculated in a relativistic impulse
approximation, using the Kemmer-Duffin-Petiau formalism to calculate the
$\pi^{\pm}$ nucleus optical potential.


title: Electroweak Processes in Few-Nucleon Systems

abstract:
  After a brief introduction into the basic ingredients of electroweak theory
as a spontaneously broken local, non-Abelian gauge symmetry, the general
properties of the electromagnetic current and two-photon operators are
discussed. The specific forms of vector and axial one-nucleon currents are
given, together with lowest order $\pi$ meson exchange and isobar currents as
well as meson production currents. A brief overview is given on the most
important one- and two-boson processes. Electron scattering in the one-boson-
approximation is then considered in greater detail. Formal expressions of the
cross section for inclusive and exclusive processes are given, including parity
violating contributions from $\gamma$-$Z$ interference as well as from parity
violating components in the hadronic wave function. Specific electromagnetic
reactions on the deuteron are then discussed with respect to the influence of
meson exchange currents, isobar configurations in the deuteron groundstate,
relativistic contributions and the role of $\pi$-meson retardation.
Furthermore, recent results on coherent and incoherent $\pi$- and
$\eta$-photoproduction are presented as well as a discussion of the
Gerasimov-Drell-Hearn sum rule and the effect of a parity violating deuteron
component on inclusive electron scattering off the deuteron for quasifree
kinematics. The review closes with a summary and a brief outlook.


title: Analysis of eta production using a generalized Lee model

abstract:
  We have investigated the processes N($\pi$, $\pi$)N and N($\pi$, $\eta$)N
close to eta threshold using a simple, nonrelativistic Lee model which has the
advantage of being analytically solvable. It is then possible to study the
Riemann sheets of the S-matrix and the behavior of its resonance poles
especially close to threshold. A theoretical simulation of the experimental
cusp effect at eta threshold leads to a characteristic distribution of poles on
the Riemann sheets. We find a pole located in the $4^{th}$ Riemann sheet that
up to now has not been discussed. It belongs to the cusp peak at eta threshold.
In addition we obtain the surprising result using the Lee model that the
resonance $S_{11}(1535)$ does not play a large role. The main features of the
experimental data can be reproduced without explicitly introducing this
resonance. Furthermore, we have also studied the reactions N($\gamma$, $\pi$)N
and N($\gamma$, $\eta$)N and find reasonable agreement between the data and
both models with and without the $S_{11}(1535)$ resonance.


title: Eta photoproduction

abstract:
  We present a combined analysis of the new eta photoproduction data for total
and differential cross sections, target asymmetry and photon asymmetry. Using
basic assumptions, this allows a model-independent extraction of the $E_{2-}$
and $M_{2-}$ multipoles as well as resonance parameters of the $D_{13}(1520)$
state. At higher energy, we show that the photon asymmetry is extremely
sensitive to small multipoles that are excited by photons in the helicity 3/2
state. These could be, e.g., the $F_{15}(1680)$, the $F_{17}(1990)$, or the
$G_{17}(2190)$ resonances.


title: Shell Effects on Rotational Damping in Superdeformed Nuclei

abstract:
  Damping of rotational motion in superdeformed Hg and Dy-region nuclei is
studied by means of cranked shell model diagonalization. It is shown that a
shell oscillation in single-particle alignments affects significantly
properties of rotational damping. Onset properties of damping and damping width
for Hg are quite different from those for Dy-region superdeformed nuclei.


title: Orderly spectra from random interactions

abstract:
  We investigate the low-lying spectra of many-body systems with random
two-body interactions, specifying that the ensemble be invariant under
particle-hole conjugation.Surprisingly we find patterns reminiscent of more
orderly interactions, such as a predominance of J=0 ground states separated by
a gap from the excited states, and evidence of phonon vibrations in the
low-lying spectra.


title:
Electron-deuteron scattering in a current-conserving description of
  relativistic bound states: formalism and impulse approximation calculations

abstract:
  The electromagnetic interactions of a relativistic two-body bound state are
formulated in three dimensions using an equal-time (ET) formalism. This
involves a systematic reduction of four-dimensional dynamics to a
three-dimensional form by integrating out the time components of relative
momenta. A conserved electromagnetic current is developed for the ET formalism.
It is shown that consistent truncations of the electromagnetic current and the
$NN$ interaction kernel may be made, order-by-order in the coupling constants,
such that appropriate Ward-Takahashi identities are satisfied. A meson-exchange
model of the $NN$ interaction is used to calculate deuteron vertex functions.
Calculations of electromagnetic form factors for elastic scattering of
electrons by deuterium are performed using an impulse-approximation current.
Negative-energy components of the deuteron's vertex function and retardation
effects in the meson-exchange interaction are found to have only minor effects
on the deuteron form factors.


title:
Medium effect on photon production in ultrarelativistic nuclear
  collisions

abstract:
  The effect of in-medium vector and axial-vector meson masses on photon
production is studied. We assume that the effective mass of a vector meson in
hot nuclear matter decreases according to a universal scaling law, while that
of an axial-vector meson is given by Weinberg's mass formula. We find that the
thermal production rate of photons increases with reduced masses, and is
enhanced by an order of magnitude at T=160 MeV with $m_\rho=300$ MeV. Assuming
a hydrodynamic evolution, we estimate the effect of the reduced masses on
photon production in nucleus-nucleus collisions. The result is compared to
experimental data from the WA80/WA98 collaboration.


title: Regularization Methods for Nucleon-Nucleon Effective Field Theory

abstract:
  Attempts to apply effective field theory (EFT) methods to nonrelativistic
nucleon-nucleon (NN) scattering have raised questions about the nature and
limitations of an EFT expansion when used nonperturbatively. We discuss the
characteristics of a meaningful EFT analysis and compare them with traditional
approaches to NN scattering. A key feature of an EFT treatment is a systematic
expansion in powers of momentum, which we demonstrate using an error analysis
introduced by Lepage. A clear graphical determination of the radius of
convergence for the momentum expansion is also obtained. We use these
techniques to compare cutoff regularization, two forms of dimensional
regularization, and the dibaryon approach, using a simple model for
illustration. The naturalness of the parameters and predictions for bound-state
energies are also shown.


title: Photoprocesses on the 6Li nucleus in the potential cluster model

abstract:
  The photodisintegration of the 6Li nucleus through the channels 3He3H, 4He2H
and the corresponding radiative capture are considered in simple two-cluster
models. Potentials with forbidden states which reproduce the phase shifts of
elastic scattering up to energies of 20 MeV are was used to describe cluster
interactions. It is shown that such the potential cluster model provides an
accurate description of total cross sections for photonuclear processes over
the entire energy region under consideration.


title:
Peripheral NN-Scattering: Role of Delta-Excitation, Correlated Two-Pion
  and Vector Meson Exchange

abstract:
  We evaluate, within one-loop chiral perturbation theory, the two-pion
exchange diagrams with single and double delta-isobar excitation contributing
to elastic NN-scattering. We find that virtual $\Delta$-excitation processes
(in the static limit) produce the correct amount of isoscalar central
attraction as needed in the peripheral partial waves with $L\geq 3$.
Furthermore we compute the two-loop diagrams involving the $\pi\pi$-interaction
(so-called correlated $2\pi$-exchange). Contrary to common believe these
processes lead to negligibly small and repulsive corrections to the
NN-potential. The exchange of vector mesons ($\rho, \omega$) turns out to be
important for the F-wave phase shifts above $T_{lab}=150$ MeV. Without
adjustable parameters we are able to reproduce the empirical NN phase shifts up
to 350 MeV for $L\geq 3$ and up to about (50--80) MeV for the D-waves. This is
therefore the characteristic window in which the NN-interaction is basically
governed by chiral symmetry. Not surprisingly, the lower partial waves require
non-perturbative methods and additional short-distance parametrizations of the
NN-dynamics.


title:
The electron screening in OH-->F transition both for bound and
  scattering states

abstract:
  We estimate the nuclear fusion rates for the transition OH-->F from the
ground and excited molecular states and also consider effect of screening of
electric charges of nuclei by bound electrons in the case of colliding atoms O
and H. We show that the fusion rate for the molecular state is vanishingly
small while the electron screening drastically changes the rate for the
colliding atoms at kinetic energies up to hundreds of keV. The latter may be of
consequence for some astrophysical applications.


title: Coulomb form factors of 6Li and 7Li in potentials cluster model

abstract:
  Elastic and inelastic Coulomb form factors of 6Li and 7Li nuclei are
considered on the basis of 4He2H and 3He3H cluster models. Potentials
containing forbidden states, which describe main characteristics of bound
states and phase shifts of elastic scattering at low energies, are used as
intercluster potentials. It is obtained a good description of elastic form
factors for momenta up to 4 Fm-1 as well as the second maximum at 3 - 4 Fm-1 in
the calculated elastic form factors. The amplitude of this maximum for
inelastic form factors is smaller than the experimental value.


title:
Observation of Partial U_A(1) Restoration from Two-Pion Bose-Einstein
  Correlations

abstract:
  The effective intercept parameter of the two-pion Bose-Einstein correlation
function, lambda_*, is found to be sensitive to the partial restoration of
U_A(1) symmetry in ultra-relativistic nuclear collisions. An increase in the
yield of the eta' meson, proposed earlier as a signal of partial U_A(1)
restoration, is shown to create a ``hole'' in the low p_t region of lambda_*. A
comparison with NA44 data from central S+Pb collisions at 200 AGeV is made and
implications for future heavy ion experiments are discussed.


title: Two-Nucleon Systems from Effective Field Theory

abstract:
  We elaborate on a new technique for computing properties of nucleon-nucleon
interactions in terms of an effective field theory derived from low energy NN
scattering data. Details of how the expansion is carried out to higher orders
are presented. Analytic formulae are given for the amplitude to subleading
order in both the 1S0 and 3S1-3D1 channels.


title:
Photodisintegration of 4He nucleus into p3H and n3He channels in the
  potential cluster models

abstract:
  Processes of direct cluster photodisintegration of 4He nucleus into p3H and
n3He channels are considered on the base of two-cluster potential models.
Intercluster interactions being in agreement with elastic scattering phase
shifts and characteristics of the bound state of a nucleus have, in some cases,
forbidden states. The scattering phase shifts and potentials are separated in
the channels with minimum spin on the base of Young schemes and isospin states.


title: The first excited states of 9Be and 9B

abstract:
  It is found here that the 1/2+ first excited state of 9Be is a virtual state
with the energy of -23.5 KeV. The line shape for the excitation of the state is
approximated with a simple analytic form based on the effective range
expansion. The partner in 9B of this state is found to be a resonance with a
maximum in the peak at about 1.1 MeV, FWHM of 1.5 MeV, and complex energy of
0.6-i0.75 MeV. The line shape for its excitation is calculated in terms of the
p-8Be phase shift. The phase shifts are obtained from N-8Be effective
potentials deduced from the data on on the photodisintegration of 9Be. A
possibility for direct extraction of the energy of the resonant state from
experimental data is also discussed, and an expression for a residue at a
virtual state pole in terms of a quadrature taken over the virtual state
eigenfunction is given.


title:
8Li electron spectrum versus 8B neutrino spectrum: implications for the
  Sudbury Neutrino Observatory

abstract:
  The sensitivity of the Sudbury Neutrino Observatory (SNO) to measure the
shape of the recoil electron spectrum in the charged-current reaction of
$^{8}$B solar neutrinos interacting with deuterium can be improved if the
results of a $^{8}$Li beta-decay calibration experiment are included in the
test. We calculate an improvement in sensitivity, under certain idealistic
assumptions, of about a factor of 2, sufficient to resolve different
neutrino-oscillation solutions to the solar-neutrino problem. We further
examine the role of recoil and radiative corrections on both the $^{8}$B
neutrino spectrum and the $^{8}$Li electron spectrum and conclude that the
influence of these effects on the ratio of the two spectra as measured by SNO
is very small.


title:
Nucleon generalized polarizabilities within a relativistic Constituent
  Quark Model

abstract:
  Nucleon generalized polarizabilities are investigated within a relativistic
framework, defining such quantities through a Lorentz covariant multipole
expansion of the amplitude for virtual Compton scattering. The key physical
ingredients in the calculation of the nucleon polarizabilities are the Lorentz
invariant reduced matrix elements of the electromagnetic transition current,
which can be evaluated from off-energy-shell helicity amplitudes. The evolution
of the proton paramagnetic polarizability, $\beta_{para}(q)$, as a function of
the virtual-photon three-momentum transfer $ q,$ is explicitly evaluated within
a relativistic constituent quark model by adopting transition form factors
obtained in the light-front formalism. The discussion is focussed on the role
played by the effects due to the relativistic approach and to the transition
form factors, derived within different models.


title:
Photoprocesses for the 3H4He and 3He4He channels in the cluster
  potential model

abstract:
  Radiative capture in the 4He3H and 4He3He channels are considered for the 7Li
and 7Be nuclei. The analysis is based on the corresponding two-cluster models.
The potentials of cluster interaction include forbidden states and are made to
be consistent with the phase shifts of elastic scattering at energies up to 20
MeV. Such an approach is shown to describe the total cross sections for
photoprocesses over the entire energy region under consideration.


title:
Radiative capture in 4He12C channel of 16O nucleus in the potential
  cluster model

abstract:
  Radiative capture processes in 4He12C channel of 16O nucleus are considered
on the basis of potential two-cluster model with intercluster interactions
which contain forbidden states and reproduce phase shifts of elastic scattering
and some characteristics of bound states. Astrophysical S-factors are
calculated at low energies. It was shown that the model used enables to
describe the total cross-sections of the photoprocesses.


title: Formation of correlations and energy-conservation at short time scales

abstract:
  The formation of correlations due to collisions in an interacting nucleonic
system is investigated. Results from one-time kinetic equations are compared
with the Kadanoff and Baym two-time equation with collisions included in Born
approximation. A reasonable agreement is found for a proposed approximation of
the memory effects by a finite duration of collisions. This form of collision
integral is in agreement with intuitive estimates from Fermi's golden rule. The
formation of correlations and the build up time is calculated analytically for
the high temperature and the low temperature limit. Different approximate
expressions are compared with the numerical results. We present analytically
the time dependent interaction energy and the formation time for Gau\ss{}- and
Yukawa type of potentials.


title: New collective mode due to collisional coupling

abstract:
  Starting from a nonmarkovian conserving relaxation time approximation for
collisions we derive coupled dispersion relations for asymmetric nuclear
matter. The isovector and isoscalar modes are coupled due to asymmetric nuclear
meanfield acting on neutrons and protons differently. A further coupling is
observed by collisional correlations. The latter one leads to the appearance of
a new soft mode besides isoscalar and isovector modes in the system. We suggest
that this mode might be observable in asymmetric systems. This soft mode
approaches the isovector mode for high temperatures. At the same time the
isovector mode remains finite and approaches a constant value at higher
temperatures showing a transition from zero sound like damping to first sound.
The damping of the new soft mode is first sound like at all temperatures.


title: The Status of the Pion-Nucleon Coupling Constant

abstract:
  A review is given of the various determinations of the different piNN
coupling constants in analyses of the low-energy pp, np, pbarp, and pi-p
scattering data. The most accurate determinations are in the energy-dependent
partial-wave analyses of the NN data. The recommended value is f^2 = 0.075 . A
recent determination of f^2 by the Uppsala group from backward np cross
sections is shown to be model dependent and inaccurate, and therefore
completely uninteresting. We also argue that an accurate determination of f^2
using pp forward dispersion relations is not a realistic option.


title: The Nuclear Sigma Term in the Skyrme Model: Pion-Nucleus Interaction

abstract:
  The nuclear sigma term is calculated including the nuclear matrix element of
the derivative of the NN interaction with respect to the quark mass,
$m_q\frac{\partial V_{NN}}{\partial m_q}$. The NN potential is evaluated in the
skyrmion-skyrmion picture within the quantized product ansatz. The contribution
of the NN potential to the nuclear sigma term provides repulsion to the
pion-nucleus interaction. The strength of the s-wave pion-nucleus optical
potential is estimated including such contribution. The results are consistent
with the analysis of the experimental data.


title:
Exponential Potential for Nucleon-Nucleon Interaction with forbidden
  states

abstract:
  An exponential version of a deep nucleon-nucleon potential involving
forbidden states and a tensor component is proposed. The parameters of
interaction are chosen by fitting the low-energy characteristics and phase
shifts of np scattering at energies up to 500 MeV.


title: Systematic Theoretical Search for Dibaryons in a Relativistic Model

abstract:
  A relativistic quark potential model is used to do a systematic search for
quasi-stable dibaryon states in the $u$, $d$, and $s$ three flavor world.
Flavor symmetry breaking and channel coupling effects are included and an
adiabatic method and fractional parentage expansion technique are used in the
calculations. The relativistic model predicts dibaryon candidates completely
consistent with the nonrelativistic model.


title: Electron Screening in 7Be + p --> 8B + photon reaction

abstract:
  We evaluate the effect of screening by bound electron in (7Be,e) + p -->
(8B,e) + photon transition in the framework of the adiabatic representation of
the three particle problem. Comparison with two approaches (united nucleus and
static) is presented. We discuss possible applications of this effect both for
Solar Neutrinos and low energy fusion experiments.


title: Pion Dissociation In Hot Quark Medium

abstract:
  Pion dissociation in a medium of hot quark matter is studied. The decay width
of pion is found to be large but finite at temperatures much higher than the so
called critical temperature of chiral or deconfinement transition.
Consequently, pions should coexist with quarks and gluons at such high
temperatures. The result is in agreement with the lattice calculations. The
implication of the above result in the study of Quark-Gluon plasma is
discussed.


title:
Exponential potential of NN interactions with forbidden state in S -
  wave

abstract:
  An exponential version of a deep nucleon-nucleon potential involving
forbidden states and a tensor component is proposed. The parameters of
interaction are chosen by fitting the low-energy characteristics and phase
shifts of np scattering at energies up to 500 MeV. Such potential have not node
in D wave as against earlier proposed.


title: Dependence of lepton pair emission on EoS and initial state

abstract:
  We present results from a hydrodynamic calculation for thermal emission of
lepton pairs in central lead-lead collisions at the CERN SPS energy. Dependence
of the emission on the initial conditions and Equation of State (EoS) is
considered and the spectra are compared with CERES data and calculated
distribution of Drell--Yan pairs.


title: Electromagnetic properties of off-shell particles and gauge invariance

abstract:
  Electromagnetic properties of off-shell particles are discussed on the basis
of a purely electromagnetic reaction: virtual Compton scattering off a proton.
It is shown that the definition of off-shell electromagnetic form factors is
not gauge invariant and that these cannot be investigated in practice. Using
only fundamental requirements of gauge invariance it is demonstrated that
off-shell effects are cancelled in the longitudinal components of the total
conserved current by the minimal contact current, while the off-shellness
appears only in the the transverse (gauge invariant) non-pole part. This
provides the possibility to introduce an on-shell extrapolated form factor
F_1^+(q^2) in a gauge invariant way for the unphysical time-like region,
4m_e^2<q^2, 4M_N^2.


title: Charmonium Suppression with cc~ Dissociation by Strings

abstract:
  We study the production of cc~ pairs in nuclear reactions at SPS energies
within the covariant transport approach HSD. The production of cc~ is treated
perturbatively employing experimental cross sections while the interactions of
cc~ pairs with baryons are included by conventional cascade-type two-body
collisions. Adopting 6 mb for the cc~-baryon cross sections the data on J/\Psi
suppression in p+A reactions are reproduced in line with calculations based on
the Glauber model. Additionally the dissociation of the cc~ pairs by strings is
included in a purely geometrical way. We find good agreement with experimental
data from the NA38 and NA50 collaboration with an estimate for the string
radius of ~0.2-0.3 fm.


title:
Coherent Photoproduction of Pions on Spin-Zero Nuclei in a relativistic,
  non-local Model

abstract:
  A relativistic and non-local model for the coherent photoproduction of pions
on spin-zero nuclei is presented. The production operator is derived from an
effective Lagrangian model that contains all the degrees of freedom known to
contribute to the elementary process. Using the framework of DWIA, the matrix
elements of this operator are evaluated using relativistic bound state wave
functions. Final state interactions are accounted for via a pion-nucleus
optical potential. The effects of in-medium modifications of the production
operator are discussed. We give results for $^{12}C$ and $^{40}Ca$, and compare
our calculations to the data of the A2 collaboration at MAMI.


title: Antiproton Production in p+d Reaction at Subthreshold Energies

abstract:
  An enhancement of antiprotons produced in p+d reaction in comparison with
ones in p+p elementary reaction is investigated.
  In the neighborhood of subthreshold energy the enhancement is caused by the
difference of available energies for antiproton production. The cross section
in p+d reaction, on the other hand, becomes just twice of the one in elementary
p+p reaction at the incident energy far from the threshold energy when
non-nucleonic components in deuteron target are not considered.


title: Beta decay and shape isomerism in 74Kr

abstract:
  We study the properties of $^{74}$Kr, and particularly the Gamow Teller
strength distribution, using a deformed selfconsistent HF+RPA method with
Skyrme type interactions. Results are presented for two density-dependent
effective two-body interactions, including the dependence on deformation of the
HF energy that exhibits two minima at close energies and distant deformations,
one prolate and one oblate. We study the role of deformation, residual
interaction, pairing and RPA correlations on the Gamow Teller strength
distribution. Results on moments of inertia and gyromagnetic factors, as well
as on $E0$ and $M1$ transitions are also presented.


title:
One- and two-neutron capture reactions of light nuclei in nuclear
  astrophysics

abstract:
  We discuss models to calculate one- and two-neutron capture reactions on
light nuclei. These are applied to calculate the reaction rates of
15N(n,gamma)16N, 16N(n,gamma)17}N and 4He(2n,gamma)6He. The possible
astrophysical importance is discussed.


title: A model of short-range correlations in the charge response

abstract:
  The validity of a model treating the short-range correlations up to the first
order is studied by calculating the charge response of an infinite system and
comparing the obtained results with those of a Fermi Hypernetted Chain
calculation.


title:
New technique for phase shift analysis: multi-energy solution of inverse
  scattering problem

abstract:
  We demonstrate a new approach to the analysis of extensive multi-energy data.
For the case of d + He-4, we produce a phase shift analysis covering for the
energy range 3 to 11 MeV. The key idea is the use of iterative perturbative
data-to-potential inversion which can produce potentials which reproduce the
data simultaneously over a range of energies. It thus effectively regularizes
the extraction of phase shifts from diverse, incomplete and possibly somewhat
contradictory data sets. In doing so, it will provide guidance to
experimentalists as to what further measurements should be made. This study is
limited to vector spin observables and spin-orbit interactions. We discuss
alternative ways in which the theory can be implemented and which provide
insight into the ambiguity problems. We compare the extrapolation of these
solutions to other energies. Majorana terms are presented for each potential
component.


title:
$\omega$ and $\rho$ Photoproduction with an Effective Quark Model
  Lagrangian

abstract:
  An unified approach for vector meson photoproduction is presented in the
constit quark model. The s- and u-channel resonance contributions are generated
using an effective quark vector-meson Lagrangian. In addition, taking into
account $\pi^0$ and $\sigma$ t-channel exchanges for diffractive production,
the available total and differential cross section data for $\omega$, $\rho^0$,
$\rho^+$, and $\rho^-$ photoproduction can be well described with the same
quark model parameter set. Our results clearly indicate that polarization
observables are essential to identify so-called "missing" resonances.


title: Using inverse scattering methods to study inter-nucleus potentials

abstract:
  It is now straightforward to carry out S-matrix to potential inversion over a
very wide range of energies and for a wide range of projectile-target
combinations. Inversion is possible in many cases involving spin. IP inversion
also permits direct scattering data-to-potential inversion and furnishes
powerful tools for the phenomenological analysis of nuclear scattering. The
resulting single particle potentials exhibit various generic properties which
challenge fundamental reaction theories as well as yield information on
densities, provide input for reaction calculations. S-matrix to potential
inversion is also a powerful tool for directly investigating theoretical
processes which contribute to inter-nuclear potentials. Various studies have
given insight into contributions to the dynamic polarisation potential (DPP)
due to breakup processes and due to collective and reaction channel coupling
and have also illuminated the role played by exchange processes in leading to
non-locality and parity dependence of the potentials. A case study involving d
+ He-4 is a model for ways in which inversion applied jointly to theory and
experiment might illuminate the scattering of exotic nuclei.


title: Flavor and Charge Symmetry in the Parton Distributions of the Nucleon

abstract:
  Recent calculations of charge symmetry violation(CSV) in the valence quark
distributions of the nucleon have revealed that the dominant symmetry breaking
contribution comes from the mass associated with the spectator quark
system.Assuming that the change in the spectator mass can be treated
perturbatively, we derive a model independent expression for the shift in the
parton distributions of the nucleon. This result is used to derive a relation
between the charge and flavor asymmetric contributions to the valence quark
distributions in the proton, and to calculate CSV contributions to the nucleon
sea. The CSV contribution to the Gottfried sum rule is also estimated, and
found to be small.


title: Isovector Pairing in Odd-A Proton-Rich Nuclei

abstract:
  A simple model based on the group SO(5) suggests that both the like-particle
and neutron-proton components of isovector pairing correlations in odd-A nuclei
are Pauli blocked. The same effect emerges from Monte Carlo Shell-model
calculations of proton-rich nuclei in the full fp shell. There are small
differences between the two models in their representation of the effects of an
odd nucleon on the competition between like-particle and neutron-proton
pairing, but they can be understood and reduced by using a two-level version of
the SO(5) model. On the other hand, in odd-odd nuclei with N not equal to Z
SO(5) disagrees more severely with the shell model because it incorrectly
predicts ground-state isospins. The shell model calculations for any fp-shell
nuclei can be extended to finite temperature, where they show a decrease in
blocking.


title: Kinetic equation consistent with the equation of state of nuclear matter

abstract:
  A kinetic equation which combines the quasiparticle drift of Landau's
equation with a dissipation governed by a nonlocal and noninstant scattering
integral in the spirit of Snider's equation for gases is derived. Consequent
balance equations for the density, momentum and energy include quasiparticle
contributions and the second order quantum virial corrections. The medium
effects on binary collisions are shown to mediate the latent heat, i.e., an
energy conversion between correlation and thermal energy. An implementation to
heavy ion collisions is discussed.


title: Current Issues in the Nuclear Chiral Perturbation Approach

abstract:
  After outlining the basic ideas of nuclear chiral perturbation theory, I
discuss its application, presenting three examples which I believe are of great
current interest: (1) Exchange currents in those cases where the leading
chiral-order terms dominate; (2) The near-threshold $p+p\ra p+p+\pi^0$
reaction, for which the leading order terms are suppressed and consequently
higher-order corrections play a prominent role; (3) Radiative $\mu$-capture on
the proton.


title:
Vector Meson Photoproduction with an Effective Lagrangian in the Quark
  Model II: $\omega$ Photoproduction

abstract:
  An investigation of $\gamma p\to \omega p$ is presented in a constituent
quark model approach. The sparse data in the large $t$ region where the
resonances dominate is well described within the model, while the diffractive
behavior in the small $t$ region requires an additional t-channel exchange.
Taking into account the t-channel $\pi^0$ exchange, we find a good overall
agreement with the available data with only 3 free parameters. Our study shows
that the differential cross section is not sensitive to s-channel resonances,
however, the polarization observables are demonstrated to be very sensitive.
Thus, measuring polarization observables is the crucial part of the vector
meson photoproduction program in the search for "missing" resonances.


title:
The photoprocesses in the Nd and d3He systems on the basis of potential
  cluster models

abstract:
  Direct cluster disintegration and radiative capture in the pd, nd, and d3He
channels are considered on the basis of potential two-cluster models.
Interaction between clusters is described by potentials that, in some cases,
involve forbidden states and which are fitted to the phase shifts of elastic
scattering at low energies. Phase shifts and potentials of scattering are
separated according to the Young orbital diagrams.


title:
Photodisintegration of the 7Li nucleus through the n6Li channel in the
  potential cluster model

abstract:
  The photodisintegration of the 7Li nucleus through the n6Li channel is
considered on the basis of a potential two-cluster model.
Intercluster-interaction potentials involve forbidden states and reproduce the
phase shifts of low-energy elastic scattering that are obtained by the
resonating-group method. The proposed model is shown to describe the total
cross section for photodisintegration in the energy range under consideration.


title: Nucleon-Nucleon potentials with forbidden states up to 500 MeV

abstract:
  Central nucleon-nucleon potentials involving forbidden states are obtained
for the Gaussian, exponential, and Yukawa type. The parameters of interaction
are obtained by fitting the scattering phase shifts for energies up to 500 MeV,
low-energy parameters, and some features of the deuteron. The deuteron form
factor for low momentum transfers, the momentum distributions of nucleons, and
the cross section for deuteron photodisintegration are calculated.


title: The d'-dibaryon in a colored cluster model

abstract:
  The mass and wave function of a six-quark system with quantum numbers
J^P=0^-, T=0, called d', are calculated. We use a colored diquark-tetraquark
cluster model for the six-quark wave function. A constituent quark model
Hamiltonian with a two-body confinement potential, and residual one-gluon,
one-pion, and one-sigma exchange interactions is used. The complications due to
the quark exchange interactions between tetraquark and diquark clusters (Pauli
principle) are taken into account within the framework of the Resonating Group
Method. The calculated d' mass is some 350 MeV above the empirical value if the
same two-body confinement strength as in the nucleon and Delta is used. This
paper also examines the validity of the usual assumption of a universal
two-quark confinement strength. We propose that the effective two-body
confinement strength in an exotic six-quark system, such as the d', could be
weaker than in a single baryon. The weaker confinement hypothesis leads to a d'
mass of M=2092 MeV and a d' radius of r=1.53 fm.


title:
Symmetric and asymmetric nuclear matter in the relativistic approach at
  finite temperatures

abstract:
  The properties of hot matter are studied in the frame of the relativistic
Brueckner-Hartree-Fock theory. The equations are solved self-consistently in
the full Dirac space. For the interaction we used the potentials given by
Brockmann and Machleidt. The obtained critical temperatures are smaller than in
most of the nonrelativistic investigations. We also calculated the
thermodynamic properties of hot matter in the relativistic Hartree--Fock
approximation, where the force parameters were adjusted to the outcome of the
relativistic Brueckner--Hartree--Fock calculations at zero temperature. Here,
one obtains higher critical temperatures, which are comparable with other
relativistic calculations in the Hartree scheme.


title:
Analysis of exchange terms in a projected ERPA Theory applied to the
  quasi-elastic (e,e') reaction

abstract:
  A systematic study of the influence of exchange terms in the longitudinal and
transverse nuclear response to quasi-elastic (e,e') reactions is presented. The
study is performed within the framework of the extended random phase
approximation (ERPA), which in conjuction with a projection method permits a
separation of various contributions tied to different physical processes. The
calculations are performed in nuclear matter up to second order in the residual
interaction for which we take a (pi+rho)-model with the addition of the
Landau-Migdal g'-parameter. Exchange terms are found to be important only for
the RPA-type contributions around the quasielastic peak.


title: S-wave $\pi^0$ Production in pp Collision in a Covariant OBE Model

abstract:
  The total cross section for the pp -> pp pi^0 reaction at energies close to
threshold is calculated using a covariant one-boson-exchange model, where a
boson B created on one of the incoming protons is converted into a neutral pion
on the second. The amplitudes for the conversion processes, B N -> N pi^0, are
taken to be the sum of s, u and t-channel pole terms. The main contributions to
the primary production amplitude is due to an effective isoscalar sigma meson
pole in a t-channel, which is enhanced strongly due to offshellness. With this
contribution included the model reproduces, both the scale and energy
dependence of the cross section.


title:
$\chi$PT Calculations with two-pion Loops for S-wave $\pi^0$ Production
  in pp Collision

abstract:
  The total cross section for the $pp \to pp \pi^0$ reaction at energies close
to threshold is calculated within the frame of a chiral perturbation theory,
taking into account tree and one loop diagrams up to chiral order D=2. Two-pion
loop contributions dominate $\pi^0$ production at threshold. The calculated
cross section reproduces data, both scale and energy dependence, fairly well.


title: Analysis of chiral and thermal susceptibilities

abstract:
  We calculate the chiral and thermal susceptibilities for two confining
Dyson-Schwinger equation models of QCD with two light flavours, a quantitative
analysis of which yields the critical exponents, beta and delta, that
characterise the second-order chiral symmetry restoration transition. The
method itself is of interest, minimising the influence of numerical noise in
the calculation of the order parameter for chiral symmetry breaking near the
critical temperature. For the more realistic of the two models we find: T_c
approx. 153 MeV, and the non-mean-field values: beta = 0.46 +/- 0.04, delta =
4.3 +/- 0.3 and 1/(beta delta)= 0.54 +/- 0.05, which we discuss in comparison
with the results of other models.


title:
Analysis of NN Amplitudes up to 2.5 GeV: An Optical Model and Geometric
  Interpretation

abstract:
  We analyse the SM97 partial wave amplitudes for nucleon--nucleon (NN)
scattering to 2.5 GeV, in which resonance and meson production effects are
evident for energies above pion production threshold. Our analyses are based
upon boson exchange or quantum inversion potentials with which the
sub-threshold data are fit perfectly. Above 300 MeV they are extrapolations, to
which complex short ranged Gaussian potentials are added in the spirit of the
optical models of nuclear physics and of diffraction models of high energy
physics. The data to 2.5 GeV are all well fit. The energy dependences of these
Gaussians are very smooth save for precise effects caused by the known $\Delta$
and N$^\star$ resonances. With this approach, we confirm that the geometrical
implications of the profile function found from diffraction scattering are
pertinent in the regime 300 MeV to 2.5 GeV and that the overwhelming part of
meson production comes from the QCD sector of the nucleons when they have a
separation of their centres of 1 to 1.2 fm. This analysis shows that the
elastic NN scattering data above 300 MeV can be understood with a local
potential operator as well as has the data below 300 MeV.


title:
Shell model calculation of the beta- and beta+ partial halflifes of 54Mn
  and other unique second forbidden beta decays

abstract:
  The nucleus 54Mn has been observed in cosmic rays. In astrophysical
environments it is fully stripped of its atomic electrons and its decay is
dominated by the beta- branch to the 54Fe ground state. Application of 54Mn
based chronometer to study the confinement of the iron group cosmic rays
requires knowledge of the corresponding halflife, but its measurement is
impossible at the present time. However, the branching ratio for the related
beta+ decay of 54Mn was determined recently. We use the shell model with only a
minimal truncation and calculate both beta+ and beta- decay rates of 54Mn. Good
agreement for the beta+ branch suggests that the calculated partial halflife of
the beta- decay, (4.94 \pm 0.06) x 10^5 years, should be reliable. However,
this halflife is noticeably shorter than the range 1-2 x 10^6 y indicated by
the fit based on the 54Mn abundance in cosmic rays. We also evaluate other
known unique second forbidden beta decays from the nuclear p and sd shells
(10Be, 22Na, and two decay branches of 26Al) and show that the shell model can
describe them with reasonable accuracy as well.


title: Formation time effect on J/\psi dynamical nuclear suppression

abstract:
  The proposed hadronic and string cascade model, JPCIAE, for ultrarelativistic
nucleus - nucleus collisions based on the LUND model and the PYTHIA event
generator especially, is used to investigate the $J/\psi$ suppression due to
the nuclear absorption of a $J/\psi$ in minimum bias pA and BA collisions at
200 A GeV energy. With the different sets of reasonable formation time for
hadron and $J/\psi$ the results of $J/\psi$ suppression factor from both the
usual scenario and the Glauber - like simulations are comparable with all the
NA38 pA and BA data, except the NA50 data of Pb + Pb collisions. However, the
difference between the usual scenario and the Glauber - like simulation, hence
the difference between the dynamical simulation and Glauber theory, can not be
ignored. The sensitive effect of the hadron formation time on the $J/\psi$
suppression is studied in detail. The results seem to denote that for the
$J/\psi$ suppression the meson absorption plays role in pA as well as in BA
collisions.


title: J/\Psi production, $\chi$ polarization and Color Fluctuations

abstract:
  The hard contributions to the heavy quarkonium-nucleon cross sections are
calculated based on the QCD factorization theorem and the nonrelativistic
quarkonium model. We evaluate the nonperturbative part of these cross sections
which dominates at $\sqrt{s_{NN}}\approx 20$ GeV at the Cern Super Proton
Synchrotron (SPS) and becomes a correction at $\sqrt{s_{NN}}\approx 6$ TeV at
the CERN Large Hadron Collider (LHC). $\J$ production at the CERN SPS is well
described by hard QCD, when the larger absorption cross sections of the $\chi$
states predicted by QCD are taken into account. We predict an $A$-dependent
polarization of the $\chi$ states. The expansion of small wave packets is
discussed.


title: Microscopic Models for Ultrarelativistic Heavy Ion Collisions

abstract:
  In this paper, the concepts of microscopic transport theory are introduced
and the features and shortcomings of the most commonly used ansatzes are
discussed. In particular, the Ultrarelativistic Quantum Molecular Dynamics
(UrQMD) transport model is described in great detail. Based on the same
principles as QMD and RQMD, it incorporates a vastly extended collision term
with full baryon-antibaryon symmetry, 55 baryon and 32 meson species. Isospin
is explicitly treated for all hadrons. The range of applicability stretches
from $E_{lab}< 100$ MeV/nucleon up to $E_{lab}> 200$ GeV/nucleon, allowing for
a consistent calculation of excitation functions from the intermediate energy
domain up to ultrarelativistic energies. The main physics topics under
discussion are stopping, particle production and collective flow.


title:
Tensor 2H4He Interaction and 6Li Properties in the Potential Cluster
  Model

abstract:
  A new parameterization of the gaussian 2H4He potentials with forbidden states
and tensor component which correctly reproduce scattering phase shift at low
energies is offered. On the basis these interactions in a two - cluster model
it is possible to describe all main characteristics of a 6Li nucleus bound
state, including a sign and value of a quadrupole moment.


title:
Study of Superdeformation in Non-rotating States using the
  Skyrme-Hartree-Fock Method

abstract:
  The superdeformation (SD) in non-rotating states is studied with the HF+BCS
method using the Skyrme interaction. In applying the BCS theory, the seniority
pairing force is employed, of which strengths are determined in order to
reproduce the empirical pairing gap formula, $\bar{\Delta} = 12 A^{-1/2}$ MeV,
through a smooth level density obtained in the Thomas-Fermi approximation.
Properties of superdeformation are investigated by calculating potential energy
surfaces (PES) for various sets of the pairing force strengths and the Skyrme
force parameter for 194Hg and 236,238U. The best results are obtained using
both the SkM* force and the pairing force strength determined in this paper. By
making use of this set of forces, a systematic calculation of SD states is
carried out extensively for even-even nuclei for 20 <= Z <= 82. From our
calculation, the barriers preventing the decay into the normally deformed
states are about twice as high as those predicted by Krieger et al., who used
the same Skyrme interaction but a pairing force stronger than ours. The
differences of the present results from the Nilsson-Strutinsky calculation are
analyzed.


title: The $A_y$ Puzzle and the Nuclear Force

abstract:
  The nucleon-deuteron analyzing power $A_y$ in elastic nucleon-deuteron
scattering poses a longstanding puzzle. At energies $E_{lab}$ below
approximately 30 MeV $A_y$ cannot be described by any realistic NN force. The
inclusion of existing three-nucleon forces does not improve the situation.
Because of recent questions about the $^3P_J$ NN phases, we examine whether
reasonable changes in the NN force can resolve the puzzle. In order to do this
we investigate the effect on the $^3P_J$ waves produced by changes in different
parts of the potential (viz., the central force, tensor force, etc.), as well
as on the 2-body observables and on $A_y$. We find that it is not possible with
reasonable changes in the NN potential to increase the 3-body $A_y$ and at the
same time to keep the 2-body observables unchanged. We therefore conclude that
the $A_y$ puzzle is likely to be solved by new three-nucleon forces, such as
those of spin-orbit type, which have not yet been taken into account.


title:
Electromagnetic Effects in Light Nuclei and the Potential Cluster Model.
  I

abstract:
  Photodisintegration and radiative capture in the N2H, N3H, N3He, 2H2H, 2H3He,
2H4He, 3He3H, 4He3H, and 4He3He channels are studied on the basis of the
corresponding two-cluster potential models. The astrophysical S factors at low
energies are calculated. It is shown that various electromagnetic
characteristics of light nuclei, including the Coulomb form factors at momenta
of up to 4 F-1 can be studied using a single set of intercluster interactions
containing forbidden states and consistent with the phase shifts of the cluster
low-energy elastic scattering. The calculated inelastic form factors have a
second maximum at 3-4 F-1, although it is lower than the experimental one. The
orbital states are classified for the lightest cluster systems, and the phase
shifts and intercluster potentials are separated on the basis of Young orbital
schemes.
  It is first part of the review. Other parts will be published later.


title:
Electromagnetic Effects in Light Nuclei and the Potential Cluster Model.
  II

abstract:
  Photodisintegration and radiative capture in the N2H, N3H, N3He, 2H2H, 2H3He,
2H4He, 3He3H, 4He3H, and 4He3He channels are studied on the basis of the
corresponding two-cluster potential models. The astrophysical S factors at low
energies are calculated. It is shown that various electromagnetic
characteristics of light nuclei, including the Coulomb form factors at momenta
of up to 4 F-1 can be studied using a single set of intercluster interactions
containing forbidden states and consistent with the phase shifts of the cluster
low-energy elastic scattering. The calculated inelastic form factors have a
second maximum at 3-4 F-1, although it is lower than the experimental one. The
orbital states are classified for the lightest cluster systems, and the phase
shifts and intercluster potentials are separated on the basis of Young orbital
schemes.
  It is second part of the review. Firs part on nucl-th/9803039.


title:
Electromagnetic Effects in Light Nuclei and the Potential Cluster Model.
  III

abstract:
  Photodisintegration and radiative capture in the N2H, N3H, N3He, 2H2H, 2H3He,
2H4He, 3He3H, 4He3H, and 4He3He channels are studied on the basis of the
corresponding two-cluster potential models. The astrophysical S factors at low
energies are calculated. It is shown that various electromagnetic
characteristics of light nuclei, including the Coulomb form factors at momenta
of up to 4 F-1 can be studied using a single set of intercluster interactions
containing forbidden states and consistent with the phase shifts of the cluster
low-energy elastic scattering. The calculated inelastic form factors have a
second maximum at 3-4 F-1, although it is lower than the experimental one. The
orbital states are classified for the lightest cluster systems, and the phase
shifts and intercluster potentials are separated on the basis of Young orbital
schemes. It is third part of the review. First part on nucl-th/9803039, second
part on nucl-th/9803040 .


title: Spin Information from Vector-Meson Decay in Photoproduction

abstract:
  For the photoproduction of vector mesons, all single and double spin
observables involving vector meson two-body decays are defined consistently in
the $\gamma N$ center of mass. These definitions yield a procedure for
extracting physically meaningful single and double spin observables that are
subject to known rules concerning their angle and energy evolution. As part of
this analysis, we show that measuring the two-meson decay of a photoproduced
$\rho$ or $\phi$ does not determine the vector meson's vector polarization, but
only its tensor polarization. The vector meson decay into lepton pairs is also
insensitive to the vector meson's vector polarization, unless one measures the
spin of one of the leptons. Similar results are found for all double spin
observables which involve observation of vector meson decay. To access the
vector meson's vector polarization, one therefore needs to either measure the
spin of the decay leptons, make an analysis of the background interference
effects or relate the vector meson's vector polarization to other accessible
spin observables.


title:
Electromagnetic Effects in Light Nuclei and the Potential Cluster Model.
  IV

abstract:
  Photodisintegration and radiative capture in the N2H, N3H, N3He, 2H2H, 2H3He,
2H4He, 3He3H, 4He3H, and 4He3He channels are studied on the basis of the
corresponding two-cluster potential models. The astrophysical S factors at low
energies are calculated. It is shown that various electromagnetic
characteristics of light nuclei, including the Coulomb form factors at momenta
of up to 4 F-1 can be studied using a single set of intercluster interactions
containing forbidden states and consistent with the phase shifts of the cluster
low-energy elastic scattering. The calculated inelastic form factors have a
second maximum at 3-4 F-1, although it is lower than the experimental one. The
orbital states are classified for the lightest cluster systems, and the phase
shifts and intercluster potentials are separated on the basis of Young orbital
schemes.
  It is fourth part of the review. The first part on nucl-th/9803039, second
part on nucl-th/9803040, third part on nucl-th/9803041.


title: Effects of Meson Mass Decrease on Superfluidity in Nuclear Matter

abstract:
  We calculate the $^1S_0$ pairing gap in nuclear matter by adopting the
"in-medium Bonn potential" proposed by Rapp et al. [e-print nucl-th/9706006],
which takes into account the in-medium meson mass decrease, as the
particle-particle interaction in the gap equation. The resulting gap is
significantly reduced in comparison with the one obtained by adopting the
original Bonn potential.


title:
Relativistic quantum transport theory of hadronic matter: the coupled
  nucleon, delta and pion system

abstract:
  We derive the relativistic quantum transport equation for the pion
distribution function based on an effective Lagrangian of the QHD-II model. The
closed time-path Green's function technique, the semi-classical, quasi-particle
and Born approximation are employed in the derivation. Both the mean field and
collision term are derived from the same Lagrangian and presented analytically.
The dynamical equation for the pions is consistent with that for the nucleons
and deltas which we developed before. Thus, we obtain a relativistic transport
model which describes the hadronic matter with $N$, $\Delta$ and $\pi$ degrees
of freedom simultaneously. Within this approach, we investigate the medium
effects on the pion dispersion relation as well as the pion absorption and pion
production channels in cold nuclear matter. In contrast to the results of the
non-relativistic model, the pion dispersion relation becomes harder at low
momenta and softer at high momenta as compared to the free one, which is mainly
caused by the relativistic kinetics. The theoretically predicted free $\pi N
\to \Delta$ cross section is in agreement with the experimental data. Medium
effects on the $\pi N \to \Delta$ cross section and momentum-dependent
$\Delta$-decay width are shown to be substantial.


title: Higher Order Hadronic Energy Level Shifts in Protonium

abstract:
  Using effective field theory for a proton and antiproton bound in a Coulomb
potential, the shift of the ground state energy level is calculated to
arbitrary order in the scattering length. Including the next order contact
interaction, the correction due to the effective range parameter can also be
obtained.


title:
Disappearance of Elliptic Flow: A New Probe for the Nuclear Equation of
  State

abstract:
  Using a relativistic hadron transport model, we investigate the utility of
the elliptic flow excitation function as a probe for the stiffness of nuclear
matter and for the onset of a possible quark-gluon-plasma (QGP)
phase-transition at AGS energies 1 < E_Beam < 11 AGeV. The excitation function
shows a strong dependence on the nuclear equation of state, and exhibits
characteristic signatures which could signal the onset of a phase transition to
the QGP.


title:
Role of Fragment Higher Static Deformations in the Cold Binary Fission
  of $^{252}$Cf

abstract:
  We study the binary cold fission of $^{252}$Cf in the frame of a cluster
model where the fragments are born to their respective ground states and
interact via a double-folded potential with deformation effects taken into
account up to multipolarity $\lambda=4$. The preformation factors were
neglected. In the case when the fragments are assumed to be spherical or with
ground state quadrupole deformation, the $Q$-value principle dictates the
occurence of a narrow region around the double magic $^{132}$Sn, like in the
case of cluster radioactivity. When the hexadecupole deformation is turned on,
an entire mass-region of cold fission in the range 138 - 156 for the heavy
fragment arise, in agreement with the experimental observations.
  This fact suggests that in the above mentioned mass-region, contrary to the
usual cluster radioactivity where the daughter nucleus is always a
neutron/proton (or both) closed shell or nearly closed shell spherical nucleus,
the clusterization mechanism seems to be strongly influenced by the
hexadecupole deformations rather than the $Q$-value.


title: Neutronless $^{10}$be-Accompanied Ternary Fission of $^{252}$Cf}

abstract:
  A new type of decay corresponding to the neutronless $^{10}$Be-accompanied
fragmentation of $^{252}$Cf is studied. We employ a cluster model similar to
the model used for the description of cluster radioactivity.
  No preformation factors were considered.
  The ternary relative isotopic yields were calculated as the ratio of the
penetrability of a given ternary fragmentation over the sum of penetrabilities
of all possible ternary neutronless fragmentations. The corresponding barriers
between the light and heavy fragment and between the $^{10}$Be cluster and the
two heavier fragments were computed with the help of a double folding potential
generated by M3Y-$NN$ effective interaction and realistic fragment ground state
deformations.
  Also, we studied the influence of the fragment excitation energies on the
yields, by including the level densities and the
  $\beta$-stretching of the fragments.
  The new phenomenon could be experimentally observed by the triple gamma
coincidence technique between the fragments and $^{10}$Be.


title: Molecular vibrational states in the binary cold fission of $^{252}$Cf

abstract:
  We predict a molecular vibrational state in the cold binary fission of
$^{252}$Cf using a simple decay cluster model. The Hamiltonian of two even-even
fragments in the pole-pole configuration is built in the same fashion as that
for the dinuclear molecule formed in heavy-ions collisions. The interaction
between the two fragments is described by the double-folding M3Y potential. The
spectrum of the butterfly vibrations is derived and its dependence on fragments
deformation and mass-assymetry is discussed. Some experimental implications are
commented.


title: Toroidal collective motions in the atomic nucleus

abstract:
  The work deals with one of the topics of collective motion. In the frame of
Nuclear Fluid Dynamics, a model which portrays the nuclear matter as a quantum
elastic body, the torus-like motions and their associated energies are computed
using the thirteen moment approximation. The spin-dependent collective
excitations, with toroidal electromagnetic structure, are studied by means of
the Generalized Goldhaber-Teller model, with emphasize on the 1$^{-}$ spin-flip
mode and its excitation in spherical nuclei by inelastic electron scattering.
We discuss the importance of toroidal contributions in the inclusive electron
scattering $(e, e')$ and exclusive coincidence electron scattering $(e,
e'\gamma)$. In order to extract the toroidal multipole, we use the
backscattering angles in the first mentioned reaction, and the separation of
the longitudinal/transverse interference in the second case. The introduction
of a quantity which accounts for the deviations from the Siegert theorem, shows
the importance of toroidal quadrupole transitions at high-momentum transfer.


title: Electromagnetic Radiation from Hot and Dense Hadronic Matter

abstract:
  The modifications of hadronic masses and decay widths at finite temperature
and baryon density are investigated using a phenomenological model of hadronic
interactions in the Relativistic Hartree Approximation. We consider an
exhaustive set of hadronic reactions and vector meson decays to estimate the
photon emission from hot and dense hadronic matter. The reduction in the vector
meson masses and decay widths is seen to cause an enhancement in the photon
production. It is observed that the effect of $\rho$-decay width on photon
spectra is negligible. The effects on dilepton production from pion
annihilation are also indicated.


title: Pole Term and Gauge Invariance in Deep Inelastic Scattering

abstract:
  In this paper we reconcile two contradictory statements about deep inelastic
scattering (DIS) in manifestly covariant theories: (i) the scattering must be
gauge invariant, even in the deep inelastic limit, and (ii) the pole term
(which is not gauge invariant in a covariant theory) dominates the scattering
amplitude in the deep inelastic limit. An ``intermediate'' answer is found to
be true. We show that, at all energies, the gauge dependent part of the pole
term cancels the gauge dependent part of the rescattering term, so that both
the pole and rescattering terms can be separately redefined in a gauge
invariant fashion. The resulting, redefined pole term is then shown to dominate
the scattering in the deep inelastic limit. Details are worked out for a simple
example in 1+1 dimensions.


title: Perturbative description of nuclear double beta decay transitions

abstract:
  A consistent treatment of intrinsic and collective coordinates is applied to
the calculation of matrix elements describing nuclear double beta decay
transitions. The method, which was developed for the case of nuclear rotations,
is adapted to include isospin and number of particles degrees of freedom. It is
shown that the uncertainties found in most models, in dealing with these decay
modes, are largely due to the mixing of physical and spurious effects in the
treatment of isospin dependent interactions.


title:
Thermodynamics of a finite system of classical particles with short and
  long range interactions and nuclear fragmentation

abstract:
  We describe a finite inhomogeneous three dimensional system of classical
particles which interact through short and (or) long range interactions by
means of a simple analytic spin model. The thermodynamic properties of the
system are worked out in the framework of the grand canonical ensemble. It is
shown that the system experiences a phase transition at fixed average density
in the thermodynamic limit. The phase diagram and the caloric curve are
constructed and compared with numerical simulations. The implications of our
results concerning the caloric curve are discussed in connection with the
interpretation of corresponding experimental data.


title: Two-neutron removal reactions of 6He treated as a three-body halo

abstract:
  We formulate a method to compute breakup processes of three-body halo systems
reacting with a target. The reaction between one of the particles and the
target as well as the corresponding pairwise final state interactions are
carefully treated. Both absorption and diffraction processes are included.
Detailed differential and total cross sections are calculated for two-neutron
(2n) removal from 6He by fragmentation on 12C. Effects due to the core
shadowing are taken into account. Good agreement with available experimental
data is obtained.


title: Photon- and meson-induced reactions on the nucleon

abstract:
  In an unitary effective Lagrangian model we develop a unified description of
both meson scattering and photon-induced reactions on the nucleon. Adding the
photon to an already existing model for meson-nucleon scattering yields both
Compton and meson photoproduction amplitudes. In a simultaneous fit to all
available data involving the final states $\gamma N$, $\pi N$, $\pi\pi N$,
$\eta N$ and $K \Lambda$ the parameters of the nucleon resonances are
extracted.


title:
Relativistic and Non-Relativistic Mean Field Investigation of the
  Superdeformed Bands in $^{62}$Zn

abstract:
  Following the discovery of the superdeformed(SD) band in $^{62}$Zn, we
calculate several low-lying SD bands in $^{62}$Zn using Relativistic Mean Field
and Skyrme-Hartree-Fock models. Both models predict similar results, but still
we can see some qualitative differences in the results of these two models,
which are coming from the difference of the detail of single-particle levels.


title: Seeing phi meson through the dilepton spectra in heavy-ion collisions

abstract:
  Dilepton spectra from the decay of phi mesons produced in heavy-ion
collisions at SIS/GSI energies ($\sim 2$ GeV/nucleon) are studied in the
relativistic transport model. We include phi mesons produced from
baryon-baryon, pion-baryon, and kaon-antikaon collisions. The cross sections
for the first two processes are obtained from an one-boson-exchange model,
while that for the last process is taken to be the Breit-Wigner form through
the phi meson resonance. For dileptons with invariant mass near the phi meson
peak, we also include contributions from neutron-proton bremsstrahlung,
pion-pion annihilation, and the decay of rho and omega mesons produced in
baryon-baryon and meson-baryon collisions. Effects due to medium modifications
of the kaon and vector (rho, omega and phi) meson properties are investigated.
We find that the kaon medium effects lead to a broadening of the dilepton
spectrum as a result of the increase of phi meson decay width. Furthermore, the
dropping of phi meson mass in nuclear medium leads to a shoulder structure in
the dilepton spectrum besides the main peak at the bare phi meson mass. The
experimental measurement of the dilepton spectra from heavy-ion collisions is
expected to provide useful information about the phi meson properties in dense
matter.


title:
LUCIAE 3.0: A new version of a computer program for Firecracker Model
  and rescattering in relativistic heavy-ion collisions

abstract:
  LUCIAE is a Monte Carlo program that, connected to FRITIOF, implements both
the Firecracker Model (FCM), a possible mechanism for collective multi-gluon
emission from the colour fields of interacting strings, and the reinteraction
of the final state hadrons in relativistic heavy ion collisions. This paper
includes a brief presentation of the dynamics of LUCIAE with an emphasis on the
new features in this version, as well as a description of the program.


title: Increase of Effective String Tension and Production of Strange Particles

abstract:
  The increase of effective string tension as a result of the hard gluon kinks
on a string is investigated using a parametrization form. In this form the
effective string tension increasing with energies in hadron-hadron collisions
is due to the mini-jet (gluon) production in the collisions. The data of the
energy dependence of the strange quark suppression factor in hh collisions are
very well reproduced with this mechanism. Meanwhile, the experimental phenomena
of approximate energy independence of the strange quark suppression factor in
e$^+$e$^-$-annihilations are discussed.


title:
Strange Antibaryon Production Data and Reduction of Strangeness
  Suppression in Sulphur-Nucleus Collisions at 200A GeV

abstract:
  We have used the event generator LUCIAE to analyse NA35 data of the $\bar p$
and $\bar{\Lambda}$ yields, the ratio $\bar{\Lambda}/\bar p$, and the
transverse mass distributions of $\bar p$ and $\bar{\Lambda}$ in pp and central
sulphur-nucleus collisions at 200A GeV. The NA35 data could be reproduced
reasonably if one assumes that the s quark pair suppression factor and concerns
in nucleus-nucleus collisions are larger than the nucleon-nucleon collision. It
seems to indicate that NA35 data might imply the reduction of strangeness
suppression in ultrarelativistic nucleus-nucleus collisions comparing to the
nucleon-nucleon collision at the same energy. However, the ratio
$\bar{\Lambda}/\bar p$ approaching to unity in AA collisions comparing to the
pp collision does not necessarily mean a flavor symmetry since hadronic
rescattering plays a role as well.


title:
Production of mini-(gluon)jets and strangeness enhancement in pA and AA
  collisions at relativistic energies

abstract:
  The idea that effective string tension increases as a result of the hard
gluon kinks on a string is applied to study the strange particle production in
proton-nucleus and nucleus-nucleus collisions. It is found that the effective
string tension increases with the increase of centrality and mass of the
colliding system as a consequence of the mini-(gluon)jet production stemming
from the collective string-string interaction. This mechanism leads to
strangeness enhancement in pA and AA collisions through the enhanced production
of the strange quark pairs from the color field of strings. We discuss
different roles played by this mechanism and rescattering of the final state
hadrons in the production of strange particles and compare our results with
experimental data.


title: Low-momentum effective theory for nucleons

abstract:
  Starting from a precise two-nucleon potential, we use the method of unitary
transformations to construct an effective potential that involves only momenta
less than a given maximal value. We describe this method for an S-wave
potential of the Malfliet-Tjon type. It is demonstrated that the bound and
scattering state spectrum calculated within the effective theory agrees exactly
with the one based on the original potential. This might open an avenue for the
construction of effective chiral few-nucleon forces and for a systematic
treatment of relativistic effects in few-body systems.


title: A model for pion Delta electroproduction on the proton

abstract:
  We have extended a model for the $\gamma N\to \pi\pi N$ reaction to virtual
photons and selected the diagrams which have a $\Delta$ in the final state.
With this model we have evaluated cross sections for the virtual photon cross
section as a function of $Q^2$ for different energies. The agreement found with
the $\gamma_v p\to\Delta^0\pi^+$ and $\gamma_v p\to\Delta^{++}\pi^-$ reactions
is good. The sensitivity of the results to $N\Delta$ transition form factors is
also studied. The present reaction, selecting a particular final state, is an
extra test for models of the $\gamma_{v} N\to \pi\pi N$ amplitude. The
experimental measurement of the different isospin channels for this reaction
are encouraged as a means to unravel the dynamics of the two pions
photoproduction processes.


title:
$\nu d \to \mu^- \Delta^{++} n$ Reaction and Axial Vector $N-\Delta $
  Coupling

abstract:
  The reaction $\nu d \to \mu^- \Delta^{++} n$ is studied in the region of low
$q^2$ to investigate the effect of deuteron structure and width of the $\Delta$
resonance on the differential cross section. The results are used to extract
the axial vector $N-\Delta$ coupling $C^{A}_5$ from the experimental data on
this reaction. The possibility to determine this coupling from electroweak
interaction experiments with high intensity electron accelerators is discussed.


title:
Local Thermodynamical Equilibrium and the Equation of State of Hot,
  Dense Matter Created in Au+Au Collisions at AGS

abstract:
  Local kinetic and chemical equilibration is studied for Au+Au collisions at
10.7 AGeV in the microscopic Ultrarelativistic Quantum Molecular Dynamics model
(UrQMD). The UrQMD model exhibits dramatic deviations from equilibrium during
the high density phase of the collision. Thermal and chemical equilibration of
the hadronic matter seems to be established in the later stages during a
quasi-isentropic expansion, observed in the central reaction cell
($S/A=S/A=s/\rho_B ~\cong~$ 12). At latest stages of the reactions (of order of
10 fm/c) the hadron energy spectra in the cell are nicely reproduced by
Boltzmann distributions with a common rapidly dropping temperature. Hadron
yields change drastically and at the late expansion stage follow closely those
of an ideal gas statistical model. The detailed comparison with the UrQMD box
calculations for infinite equilibrated matter is done. It also shows that the
system in the central zone reaches the equilibrium at late stages of the
reaction. The equation of state seems to be simple at late times:
$P\cong0.12\epsilon$ which coincides with Shuryak predictions for the resonance
gas. The contribution of the strange particles into the total energy density of
the system in the central region of the reaction seems to be of order of 1-3 %
(strange particle density in the central zone is negligibly small e.g.
$\rho_S=0.008$). The time evolution of other thermodynamical variables in the
cell is also presented.


title: The neutron charge form factor in helium-3

abstract:
  In order to measure the charge form factor of the neutron, $G^n_E(Q^2)$, one
needs to use a neutron bound in a nuclear target. We calculate the change in
the form factor for a neutron bound in $^3He$, with respect to the free case,
using several versions of the quark meson coupling model. It is found that the
form factor may be suppressed by as much as 12% at $Q^2 = 0.5{GeV}^2$ with
respect to that of the free neutron.


title: Nuclear Scales

abstract:
  Nuclear scales are discussed from the nuclear physics viewpoint. The
conventional nuclear potential is characterized as a black box that
interpolates nucleon-nucleon (NN) data, while being constrained by the best
possible theoretical input. The latter consists of the longer-range parts of
the NN force (e.g., OPEP, TPEP, the $\pi$-$\gamma$ force), which can be
calculated using chiral perturbation theory and gauged using modern phase-shift
analyses. The shorter-range parts of the force are effectively parameterized by
moments of the interaction that are independent of the details of the force
model, in analogy to chiral perturbation theory. Results of GFMC calculations
in light nuclei are interpreted in terms of fundamental scales, which are in
good agreement with expectations from chiral effective field theories. Problems
with spin-orbit-type observables are noted.


title: Cross Section Uncertainties in the Gallium Neutrino Source Experiments

abstract:
  The 51Cr neutrino source experiments play a unique role in testing overall
operations of the GALLEX and SAGE solar neutrino experiments. Recently Hata and
Haxton argued that the excited-state contribution to the 71Ga cross section for
51Cr neutrino absorption might not be known reliably, despite forward-angle
(p,n) measurements. A large-basis shell model calculation reported here
indicates that the unusual situation they envisioned - destructive interference
between weak spin and strong spin-tensor amplitudes - does occur for the
transition to the first excited state in 71Ge. The calculation provides a
counterexample to procedures previously used to determine the 51Cr cross
section: the predicted (p,n) cross section for this state agrees with
experiment, while the BGT value is well outside the accepted
3-standard-deviation limit. The results argue for a shift in the interpretation
of the source experiments: they become more crucial as measurements of the 71Ga
detector response to 7Be solar neutrinos, and less definitive as wholly
independent tests of 71Ge recovery and counting efficiencies.


title: Method of integral transforms for calculating few-body reactions

abstract:
  A non-conventional approach to calculating reactions in quantum mechanics is
presented. Reaction observables are obtained with bound state calculation
techniques. The accuracy of the method to calculate few-nucleon response
functions is discussed.


title: $K^-/K^+$ ratios in relativistic heavy-ion collisions

abstract:
  We study $K^-/K^+$ ratios as a function of centrality (participant nucleon
number), transverse mass ($m_t$), and rapidity, in heavy-ion collisions at beam
energies between 1A and 2A GeV. We use the relativistic transport model that
includes expicitly the strangeness degrees of freedom and consider two
scenarios for kaon properties in dense matter, one with and one without medium
modifications of their properties. In both scenarios, The $K^-/K^+$ ratio does
not change very much with the centrality, while the $K/\pi$ and ${\bar K}/\pi$
ratios increase with increasing centrality. Significant differences are
predicted, both in magnitudes and shapes, for the $m_t$ spectra and rapidity
distributions of $K^-/K^+$ ratio. Experimental measurement of these ratios,
currently under investigation by the FOPI, KaoS, E866, and E895 collaborations,
will be useful in revealing the kaon in-medium properties.


title: Large-basis shell-model calculations for p-shell nuclei

abstract:
  Results of large-basis shell-model calculations for nuclei with A=7-11 are
presented. The effective interactions used in the study were derived
microscopically from the Reid93 potential and take into account the Coulomb
potential as well as the charge dependence of T=1 partial waves. For A=7, a
$6\hbar\Omega$ model space was used, while for the rest of the studied
nuclides, the calculations were performed in a $4\hbar\Omega$ model space. It
is demonstrated that the shell model combined with microscopic effective
interactions derived from modern nucleon-nucleon potentials is capable of
providing good agreement with the experimental properties of the ground state
as well as with those of the low-lying excited states.


title: Sigma and omega meson propagation in a dense nuclear medium

abstract:
  The propagation of the scalar ($\sigma$) and vector ($\omega$) mesons in
nuclear matter is studied in detail using the Walecka model over a wide range
of densities and including the effects of a finite $\sigma$ width through the
inclusion of a two-pion loop. We calculate the dispersion relation and spectral
functions of the $\sigma$ and (transverse and longitudinal) $\omega$ mesons,
including the effect of $\sigma$-$\omega$ mixing in matter. It is shown that
the mixing effect is quite important in the propagation of the (longitudinal)
$\omega$ and $\sigma$ mesons above normal nuclear matter density. We find that
there is a two-peak structure in the spectral function of the $\sigma$ channel,
caused by $\sigma$-$\omega$ mixing.


title: Comparison of techniques for computing shell-model effective operators

abstract:
  Different techniques for calculating effective operators within the framework
of the shell model using the same effective interaction and the same excitation
spaces are presented. Starting with the large-basis no-core approach, we
compare the time-honored perturbation-expansion approach and a model-space
truncation approach. Results for the electric quadrupole and magnetic dipole
operators are presented for $^6$Li. The convergence trends and dependence of
the effective operators on differing excitation spaces and Pauli Q-operators is
studied. In addition, the dependence of the electric-quadrupole effective
charge on the harmonic-oscillator frequency and the mass number, for A=5,6, is
investigated in the model-space truncation approach.


title: Two Phase Simulation of Ultrarelativistic Nuclear Collisions

abstract:
  A two phase cascade is presented for the treatment of ultra-high energy
ion-ion collisions at energies from 17-200 GeV. First a high energy, fast
cascade is performed, in which original baryons and freed hard partons, if any,
collide. This stage ignores energy loss from soft (slow) processes. In this
first version no hard processes, aside from Drell-Yan production, are included.
The space-time history of the hard phase is then used as input to reconstruct
soft energy-loss, which occurs over a longer time scale. Soft meson production
is therefore treated as coherent over groups of interacting nucleons. Two body
data, though, are used extensively to guide the reinitialisation of the
cascade, which satisfies conservation laws for charge, strangeness and of
course, energy-momentum. A second phase, low energy cascade is finally carried
out among the products of the hard cascade. The model selected to describe
elementary hadron-hadron collisions in the soft cascade incorporates generic
mesons and baryons, which are the agents for rescattering. We imagine a
constituent quark model applies, with generic mesons consisting of an excited
quark-antiquark pair, and generic baryons constructed from three quarks. The
chief result is a reconciliation of the important Drell-Yan measurements,
indicating high-mass lepton pairs are produced as if no energy is lost from the
nucleons, with the apparent success of a purely hadronic, soft cascade in
describing nucleon stopping and meson production in heavy ion experiments at
the CERN SPS.


title: K^+ versus \Lambda flow in relativistic heavy-ion collisions

abstract:
  We study $K^+$ and $\Lambda$ flow in heavy-ion collisions at beam energies of
about 2A GeV. We present our results in both the `traditional' (i.e., in terms
of the average transverse momentum in the reaction plane) as well as `modern'
(i.e., in terms of coefficients of the Fourier analysis of azimuthal
distributions) methods of flow analysis. We find significant differences
between the $K^+$ and the $\Lambda$ flow: while the $\Lambda$ flow is basically
similar to that of nucleons, the $K^+$ flow almost disappears. This difference
is attributed chiefly to their different mean field potentials in dense matter.
The comparisons with the experimental data, as well as theoretical results from
independent calculations, indicate clearly the pivotal roles of both $K^+$ and
$\Lambda$ medium effects. We emphasize that similar experimental data from
independent collaborations are essential for the eventual verification of these
medium effects.


title: The Pion-Nucleon coupling constant from np charge exchange scattering

abstract:
  A novel extrapolation method has been used to deduce the charged Pion-Nucleon
coupling constant from backward $np$ differential scattering cross sections. We
applied it to new measurements performed at 162 MeV at the The Svedberg
Laboratory in Uppsala. In the angular range $150^\circ-180^\circ$, the
carefully normalized data are steeper than those of most previous measurements.
The extracted value, $g^2_{\pi^\pm} = 14.52 \pm 0.26$, in good agreement with
the classical value, is higher than those determined in recent nucleon-nucleon
partial-wave analyses.


title: Non-radiative synthesis of Be7 in solar plasma

abstract:
  The nuclear reaction e + He3 + He4 ---> e + Be7 is considered at
thermonuclear energies. The motion of the electron is treated within the
adiabatic approximation and the He3-He4 scattering state is calculated using an
effective He3-He4 potential constructed via the Marchenko inverse scattering
method. The reaction rate thus obtained for solar interior conditions is
approximately 10^{-4} of the corresponding rate for the radiative capture He3 +
He4 ----> Be7 + gamma. However, at the conditions corresponding to the early
stages of the primordial nucleosynthesis, the non-radiative fusion is five
times faster than the radiative one. The importance of the non-radiative
processes for the energy balance in the sun, which for electrons is totally
opaque, is discussed.


title: Relativistic Spin-Flavor States in Light Front Dynamics

abstract:
  Orthonormal spin-flavor wave functions of Lorentz covariant quark models of
the Bakamjian-Thomas type are constructed for nucleon resonances. Three
different bases are presented. The manifestly Lorentz covariant Dirac-Melosh
basis is related to the Pauli-Melosh basis and the symmetrized Bargmann-Wigner
basis that are manifestly orthogonal.


title: Strangeness Production and Ultrarelativistic Cascades

abstract:
  A two phase cascade, LUCIFER II, developed for the treatment of ultra high
energy ion-ion collisions is applied to the production of strangeness at SPS
energies $\sqrt{s}=17-20$. This simulation is able to simultaneously describe
both hard processes such as Drell-Yan and slower, soft processes such as the
production of light mesons, including strange mesons, by separating the
dynamics into two steps, a fast cascade involving only nucleons in the original
colliding relativistic ions followed, after an appropriate delay, by
multiscattering of the resulting excited baryons and mesons produced virtually
in the first step. No energy loss can take place in the short time interval
over which the first cascade takes place. The chief result is a reconciliation
of the important Drell-Yan measurements with the apparent success of standard
cascades to describe the nucleon stopping and meson production in heavy ion
experiments at the CERN SPS. A byproduct, obtained here in preliminary
calculations, is a description of strangeness production in the collision of
massive ions.


title: Charge-Asymmetry of the Nucleon-Nucleon Interaction

abstract:
  Based upon the Bonn meson-exchange model for the nucleon-nucleon ($NN$)
interaction, we study systematically the charge-symmetry-breaking (CSB) of the
$NN$ interaction due to nucleon mass splitting. Particular attention is payed
to CSB generated by the $2\pi$-exchange contribution to the $NN$ interaction,
$\pi\rho$ diagrams, and other multi-meson-exchanges. We calculate the CSB
differences in the $^1S_0$ effective range parameters as well as phase shift
differences in $S$, $P$ and higher partial waves up to 300 MeV lab. energy. We
find a total CSB difference in the singlet scattering length of 1.6 fm which
explains the empirical value accurately. The corresponding CSB phase-shift
differences are appreciable at low energy in the $^1S_0$ state. In the other
partial waves, the CSB splitting of the phase shifts is small and increases
with energy, with typical values in the order of 0.1 deg at 300 MeV in $P$ and
$D$ waves.


title:
What Do We Know about Low--Energy $\bar{K}N$ Interactions? Need and
  Possibilities of New Experiments at DA$\Phi$NE

abstract:
  We present results from a dispersion--relation investigation on a
coupled--channel analysis of $\bar{K}N$--initiated processes in the low-- and
intermediate--energy region. The analysis demonstrates both the effectiveness
of these relations to constrain the parameters of the unmeasurable ${\pi}Y$
channels and the need for better data in the low--energy region, such as could
be provided at a $\phi$--factory. (pres. by G.V. at the "International Workshop
on the Spectoscopy of Hypernuclei", Sendai, Japan, January 8-10, 1998, to be
publ. in Genshikaku Kenkyuu).


title:
Enhancement of nucleon-nucleon cross section in sidewards flowing
  nuclear matter through zero sound mode excitation

abstract:
  We investigate the modification induced on the nucleon-nucleon cross section
by screening of the interaction inside nuclear matter. The interaction is
described by the relativistic one boson exchange of $\sigma$, $\omega$ and
$\pi$ mesons. Medium effects enter as loop corrections to the meson propagators
and are characterized not only by density, but also by temperature and velocity
with respect to the center of mass of the collision. The cross section displays
peaks for some specific values of the velocity, corresponding to the excitation
of zero-sound modes of the longitudinal $\omega$ field. The enhancement factor
amounts to about 1.5 under reasonable conditions. It increases with density and
is reduced at finite temperature. These findings may have verifiable
consequences on the angular dependence of the measurable secondary particle
distributions.


title:
The physics of Hanbury Brown--Twiss intensity interferometry: from stars
  to nuclear collisions

abstract:
  In the 1950's Hanbury Brown and Twiss showed that one could measure the
angular sizes of astronomical radio sources and stars from correlations of
signal intensities, rather than amplitudes, in independent detectors. Their
subsequent correlation experiments demonstrating quantum bunching of photons in
incoherent light beams were seminal in the development of quantum optics. Since
that time the technique of "intensity interferometry" has become a valuable
probe of high energy nuclear and particle collisions, providing information on
the space-time geometry of the collision. The effect is one of the few
measurements in elementary particle detection that depends on the wave
mechanics of the produced particles. Here we discuss the basic physics of
intensity interferometry, and its current applications in high energy nuclear
physics, as well as recent applications in condensed matter and atomic physics.


title: The equation of state for nucleon matter and neutron star structure

abstract:
  Properties of dense nucleon matter and the structure of neutron stars are
studied using variational chain summation methods and the new Argonne v18
two-nucleon interaction. The neutron star gravitational mass limit obtained
with this interaction is 1.67 M_{solar}. Boost corrections to the two-nucleon
interaction, which give the leading relativistic effect of order (v/c)^2, as
well as three-nucleon interactions, are also included in the nuclear
Hamiltonian. Their successive addition increases the mass limit to 1.80 and
2.20 M_{solar}. Hamiltonians including a three-nucleon interaction predict a
transition in neutron star matter to a phase with neutral pion condensation at
a baryon number density of 0.2 fm^{-3}. We also investigate the possibility of
dense nucleon matter having an admixture of quark matter, described using the
bag model equation of state. Neutron stars of 1.4 M_{solar} do not appear to
have quark matter admixtures in their cores. However, the heaviest stars are
predicted to have cores consisting of a quark and nucleon matter mixture. These
admixtures reduce the maximum mass of neutron stars from 2.20 to 2.02 (1.91)
M_{solar} for bag constant B = 200 (122) MeV/fm^3. Stars with pure quark matter
in their cores are found to be unstable. We also consider the possibility that
matter is maximally incompressible above an assumed density, and show that
realistic models of nuclear forces limit the maximum mass of neutron stars to
be below 2.5 M_{solar}. The effects of the phase transitions on the composition
of neutron star matter and its adiabatic index are discussed.


title: Renormalising NN scattering: is power counting powerless?

abstract:
  The renormalisation of NN scattering in theories with zero-range interactions
is examined using a cut-off regularisation where the cut-off is taken to
infinity, dimensional regularisation (DR) with minimal subtraction, and DR with
power-divergence subtraction. In the infinite cut-off limit power counting
breaks down: terms of different orders in the potential contribute to the
scattering amplitude at the same order. Minimal subtraction does yield a
systematic expansion, but with a very limited range of validity for systems
that have unnaturally large scattering lengths. For a finite cut-off, the
behaviour of the couplings as the cut-off is lowered shows that a theory with a
natural scattering length approaches an IR fixed point. In the corresponding
effective theory, loop corrections can be treated perturbatively. In contrast,
if there is an IR fixed point for systems with an infinite scattering length it
must be a nonperturbative one, with no power counting. For such systems,
power-divergence subtraction appears to yield a systematic expansion, but with
a different power counting from Weinberg's. However the scheme omits IR
divergent terms that would otherwise lead to nonperturbative behaviour and so
the interpretation of the fixed point remains unclear.