title:
Parity violating elastic electron scattering and neutron density
  distributions in the Relativistic Hartree-Bogoliubov model

abstract:
  Parity violating elastic electron scattering on neutron-rich nuclei is
described in the framework of relativistic mean-field theory. Self-consistent
ground state density distributions of Ne, Na, Ni and Sn isotopes are calculated
with the relativistic Hartree- Bogoliubov model, and the resulting neutron
radii are compared with available experimental data. For the elastic scattering
of 850 MeV electrons on these nuclei, the parity-violating asymmetry parameters
are calculated using a relativistic optical model with inclusion of Coulomb
distortion effects. The asymmetry parameters for chains of isotopes are
compared, and their relation to the Fourier transforms of neutron densities is
studied. It is shown that parity-violating asymmetries are sensitive not only
to the formation of the neutron skin, but also to the shell effects of the
neutron density distribution.


title:
Systematic Study of Triaxial Deformation in the Relativistic Mean Field
  Theory

abstract:
  We use the relativistic mean field (RMF) theory to systematically study the
change of deformation of even-even nuclei in the proton-rich Xe region. We
investigate the appearance of triaxial deformation in 25 nuclei in the region
covering Z=50-58 and N=64-72 by performing constrained, triaxially symmetric
RMF calculations of their energy surfaces. We include pairing correlations
using the BCS formalism. We find that the Sn isotopes are spherical and the Te
isotopes are very gamma unstable with shallow minima around gamma = 60 degrees.
Adding more protons, the Xe, Ba and Ce isotopes have prolate deformations with
their sizes increasing with proton number. The neutron number dependence is
found to be small. We compare the calculated results with the available
experimented data on the binding energy and the radii.


title: Interactions of charmed mesons with nucleons in the $\bar p d$ reaction

abstract:
  We study the possibility to measure the elastic $\Phi N$ ($\Phi \equiv
J/\psi, \psi(2S), \psi(3770),\chi_{2c}$) scattering cross section in the
reaction $\bar p{+}d{\to}\Phi{+}n_{sp}$ and the elastic $D(\bar D) N$
scattering cross section in the reaction $\bar p{+}d \to D^- D^0 p_{sp}$. Our
studies indicate that the elastic scattering cross sections can be determined
for $\Phi$ momenta about 4-6 GeV/c and $D/ \bar D$ momenta 2 -- 5 GeV/c by
selecting events with $p_t \geq 0.4$ GeV/c for $\Phi$'s and $p_t(p_{sp})\geq$
0.5 GeV/c for $D/\bar D$-meson production.


title:
Approximate particle number projection with density dependent forces:
  Superdeformed bands in the A=150 and A=190 regions

abstract:
  We derive the equations for approximate particle number projection based on
mean field wave functions with finite range density dependent forces. As an
application ground bands of even-A superdeformed nuclei in the A=150 and A=190
regions are calculated with the Gogny force.
  We discuss nuclear properties such as quadrupole moments, moments of inertia
and quasiparticle spectra, among others, as a function of the angular momentum.
We obtain a good overall description.


title: Partial Dynamical SU(3) Symmetry in Deformed Nuclei

abstract:
  We discuss characteristic features of SU(3) partial dynamical symmetry in
relation to nuclear spectroscopy and compare with previous broken-SU(3)
calculations for ^{168}Er.


title:
A variational approach to approximate particle number projection with
  effective forces

abstract:
  Kamlah's second order method for approximate particle number projection is
applied for the first time to variational calculations with effective forces.
High spin states of normal and superdeformed nuclei have been calculated with
the finite range density dependent Gogny force for several nuclei. Advantages
and drawbacks of the Kamlah second order method as compared to the
Lipkin-Nogami recipe are thoroughly discussed. We find that the Lipkin-Nogami
prescription occasionally may fail to find the right energy minimum in the
strong pairing regime and that Kamlah's second order approach, though providing
better results than the LN one, may break down in some limiting situations.


title:
Extraction of the D13(1520) photon-decay couplings from pion- and
  eta-photoproduction data

abstract:
  We compare results for the D13(1520) photon-decay amplitudes determined in
analyses of eta- and pion-photoproduction data. The ratio of helicity
amplitudes (A_3/2 / A_1/2), determined from eta-photoproduction data, is quite
different from that determined in previous analyses of pion-photoproduction
data. We consider how strongly the existing pion-photoproduction data constrain
both this ratio and the individual photon-decay amplitudes.


title: Multi-pion production in the d d -> alpha X reaction

abstract:
  A simple model, based on two parallel and independent N N -> d pi processes,
has recently been proposed for two-pion production in the d d -> alpha X
reaction. It reproduces all observed features, including the sharp peak
structure in momentum distributions (the ABC effect) and the strong
oscillations in the deuteron vector and tensor analyzing powers. This model is
now extended to describe also four-pion production with the same basic
mechanism, but with two n p -> d pi pi processes as input. The calculations of
the high missing mass spectra are within about 30% of the experimental data for
beam energies in the range 1.9 < T_d < 2.4 GeV.


title:
Constructing Effective Pair Wave Function from Relativistic Mean Field
  Theory with a Cutoff

abstract:
  We propose a simple method to reproduce the ^1S_0 pairing properties of
nuclear matter, which are obtained using a sophisticated model, by introducing
a density-independent cutoff into the relativistic mean field model. This can
be applied successfully to the physically relevant density range.


title:
Sensitivity of tensor analyzing power in the process $d+p\to d+X$ to the
  longitudinal isoscalar form factor of the Roper resonance electroexcitation

abstract:
  The tensor analyzing power of the process $d + p \to d + X$, for forward
deuteron scattering in the momentum interval 3.7 to 9 GeV/c, is studied in the
framework of $\omega$ exchange in an algebraic collective model for the
electroexcitation of nucleon resonances. We point out a special sensitivity of
the tensor analyzing power to the isoscalar longitudinal form factor of the
Roper resonance excitation. The main argument is that the $S_{11}(1535)$,
$D_{13}(1520)$ and $S_{11}(1650)$ resonances have only isovector longitudinal
form factors. It is the longitudinal form factor of the Roper excitation, which
plays an important role in the $t-$dependence of the tensor analyzing power. We
discuss possible evidence of swelling of hadrons with increasing excitation
energy.


title:
Higher Partial Waves in an Effective Field Theory Approach to nd
  Scattering

abstract:
  The phase shifts for the higher partial waves (l\ge 1) in the spin quartet
and doublet channel of nd scattering at centre-of-mass energies up to 15 MeV
are presented at next-to-leading and next-to-next-to-leading order in an
effective field theory in which pions are integrated out. As available, the
results agree with both phase shift analyses and potential model calculations.


title: A Sketch of Two and Three Bodies

abstract:
  A cartoon of the Effective Field Theory of many nucleon systems is drawn,
concentrating on Compton scattering in the two nucleon system, and on $nd$
scattering in the three body system.


title: Parity Dependence of Nuclear Level Densities

abstract:
  A simple formula for the ratio of the number of odd- and even-parity states
as a function of temperature is derived. This formula is used to calculate the
ratio of level densities of opposite parities as a function of excitation
energy. We test the formula with quantum Monte Carlo shell model calculations
in the $(pf+g_{9/2})$-shell. The formula describes well the transition from low
excitation energies where a single parity dominates to high excitations where
the two densities are equal.


title: Nuclear Effects in High Energy Photon and Neutral Pion Production

abstract:
  We study the mechanism of the $\gamma$ and $\pi^0$ enhancement at large
transverse momenta in proton-nucleus collisions. A proposed mechanism suggests
an increase in the width of the transverse momentum distribution of partons in
a semihard process.


title: Wave Function Structure in Two-Body Random Matrix Ensembles

abstract:
  We study the structure of eigenstates in two-body interaction random matrix
ensembles and find significant deviations from random matrix theory
expectations. The deviations are most prominent in the tails of the spectral
density and indicate localization of the eigenstates in Fock space. Using ideas
related to scar theory we derive an analytical formula that relates
fluctuations in wave function intensities to fluctuations of the two-body
interaction matrix elements. Numerical results for many-body fermion systems
agree well with the theoretical predictions.


title:
On the Response Function Technique for Calculating the Random-Phase
  Approximation Correlation Energy

abstract:
  We develop a scheme to exactly evaluate the correlation energy in the
random-phase approximation, based on linear response theory. It is demonstrated
that our formula is completely equivalent to a contour integral representation
recently proposed by Donau et al. being numerically more efficient for
realistic calculations. Numerical examples are presented for pairing
correlations in rapidly rotating nuclei.


title:
Photoproduction of meson and baryon resonances in a chiral unitary
  approach

abstract:
  By means of a coupled channel non-perturbative unitary approach, it is
possible to extend the strong constrains of Chiral Perturbation Theory to
higher energies. In particular, it is possible to reproduce the lowest lying
resonances in meson-meson scattering up to 1.2 GeV using the parameters of the
O(p^2) and O(p^4) Chiral Lagrangian. The meson baryon sector can also be
tackled along similar lines. We report on an update of these results showing
some examples of photon induced reactions where the techniques have been
recently applied.


title: One- and two-proton transfer reactions with vibrational Nuclei

abstract:
  We extend a semiclassical model of transfer reactions to the case in which
one of the collision partners is a vibrational nucleus. The model is applied to
one- and two-proton stripping reactions in the 37Cl + 98Mo system, for which a
rapid transition from normal to anomalous slope in the two proton transfer
reaction at energies around the Coulomb barrier is experimentally observed.
This behavior is satisfactorily reproduced by the present extension of the
model.


title:
Phenomenological construction of a relativistic nucleon-nucleon
  interaction for the superfluid gap equation in finite density systems

abstract:
  We construct phenomenologically a relativistic particle-particle channel
interaction which suits the gap equation for nuclear matter. This is done by
introducing a density-independent momentum-cutoff parameter to the relativistic
mean field (Hartree and Hartree-Fock) models so as to reproduce the pairing
properties obtained by the Bonn-B potential and not to change the saturation
property. The interaction so obtained can be used for the Relativistic
Hartree-Bogoliubov calculation, but some reservation is necessary for the
Relativistic Hartree-Fock-Bogoliubov calculation.


title: Low-m_t charged pion asymmetry enhancement from hadronization of QGP

abstract:
  We show that in sudden hadronization of QGP a non-equilibrium value of the
pion phase space occupancy parameter gamma_q>1 is expected in order to
accommodate the entropy excess in QGP and the process of gluon fragmentation.
When gamma_q is near to its maximum allowed value, pion overabundance is shown
to arise at low $m_\bot$, where the charged pion asymmetry is also amplified.
These effects are considered and we show that their magnitude suffices to
explain pertinent experimental data obtained in 160-200AGeV Pb- and S- induced
reactions.


title:
Reaction mechanism and characteristics of T_{20} in d + ^3He backward
  elastic scattering at intermediate energies

abstract:
  For backward elastic scattering of deuterons by ^3He, cross sections \sigma
and tensor analyzing power T_{20} are measured at E_d=140-270 MeV. The data are
analyzed by the PWIA and by the general formula which includes virtual
excitations of other channels, with the assumption of the proton transfer from
^3He to the deuteron. Using ^3He wave functions calculated by the Faddeev
equation, the PWIA describes global features of the experimental data, while
the virtual excitation effects are important for quantitative fits to the
T_{20} data. Theoretical predictions on T_{20}, K_y^y (polarization transfer
coefficient) and C_{yy} (spin correlation coefficient) are provided up to GeV
energies.


title: Studying Phase Transitions in Nuclear Collisions

abstract:
  In this talk I discuss three main topics concerning the theoretical
description and observable signatures of possible phase transitions in nuclear
collisions. The first one is related to the multifragmentation of thermalized
sources and its connection to a liquid-gas phase transition in finite systems.
The second one is dealing with the Coulomb excitation of ultrarelativistic
heavy ions resulting in their deep disintegration. The third topic is devoted
to the description of a first order phase transition in rapidly expanding
matter. The resulting picture is that a strong collective flow of matter will
lead to the fragmentation of a metastable phase into droplets. If the
transition from quark-gluon plasma to hadron gas is of the first order it will
manifest itself by strong nonstatistical fluctuations in observable hadron
distributions.


title: Quark mean field model for nuclear matter and finite nuclei

abstract:
  We study nuclear matter and finite nuclei in terms of the quark mean field
(QMF) model, in which we describe the nucleon using the constituent quark
model. The meson mean fields, in particular the sigma meson, created by other
nucleons act on quarks inside a nucleon and change the nucleon properties in
nuclear medium. The QMF model predicts an increasing size of the nucleon as
well as a reduction of the nucleon mass in the nuclear environment. The present
model is applied to study the properties of finite nuclei after fixing all the
parameters by the nuclear matter properties, and it is found to give
satisfactory results on the nuclear properties.


title:
Single Photon Production in Relativisitic Heavy Ion Collisions and Quark
  Hadron Phase Transition

abstract:
  We discuss the recent developments in the study of single photon production
in relativistic heavy ion collisions. In particular their production at SPS,
RHIC, and LHC energies is re-examined in view of the results of Aurenche et al
which show that the rate of photon production from quark gluon plasma,
evaluated at the order of two loops far exceeds the rates evaluated at one-loop
level which have formed the basis of all the estimates of photons so far. We
find that the production of photons from quark matter could easily out-shine
those from the hadronic matter in certain ideal conditions. We further show
that the earlier results lending support to the possibility of quark-hadron
phase transition from the measured yield of single photons in $S+Au$ collisions
at CERN SPS remain valid when an account is made for these developments, though
they leave a scope for the formation of (chemically) non-equilibrated plasma.


title: A renormalisation-group treatment of two-body scattering

abstract:
  A Wilsonian renormalisation group is used to study nonrelativistic two-body
scattering by a short-ranged potential. We identify two fixed points: a trivial
one and one describing systems with a bound state at zero energy. The
eigenvalues of the linearised renormalisation group are used to assign a
systematic power-counting to terms in the potential near each of these fixed
points. The expansion around the nontrivial fixed point is shown to be
equivalent to the effective-range expansion.


title: Photodisintegration of Three-Body Nuclei with Realistic 2N and 3N Forces

abstract:
  Total photonuclear absorption cross sections of $^3$H and $^3$He are studied
using realistic NN and NNN forces. Final state interactions are fully included.
Two NN potential models, the AV14 and the r-space Bonn-A potentials, are
considered. For the NNN forces the Urbana-VIII and Tucson-Melbourne models are
employed. We find the cross section to be sensitive to nuclear dynamics. Of
particular interest in this work is the effect which NNN forces have on the
cross section. The addition of NNN forces not only lowers the peak height but
increases the cross section beyond 70 MeV by roughly 15%. Cross sections are
computed using the Lorentz integral transform method.


title:
Formal comparison of SUSY in the nuclear U(6/2) model and in quantum
  field theory

abstract:
  A nuclear physics example of the U(6/2) supersymmetry group is considered. It
is shown that this group contains a supersymmetric subgroup with a structure
similar to the SUSY model of the quantum field theory (QFT). A comparison of
two models help to clarify the relation between the supersymmetry schemes of
QFT and of nuclear physics. Using this similarity a relation between the
numbers of the bosonic and fermionic states similar to the fundamental relation
in QFT is obtained. For those supermultiplets with at least two fermions the
number of the bosonic and fermionic states are equal as in QFT.


title:
Photo- and Electro-Disintegration of 3He at Threshold and pd Radiative
  Capture

abstract:
  The present work reports results for: pd radiative capture observables
measured at center-of-mass (c.m.) energies in the range 0--100 keV and at 2 MeV
by the TUNL and Wisconsin groups, respectively; contributions to the
Gerasimov-Drell-Hearn (GDH) integral in 3He from the two- up to the three-body
breakup thresholds, compared to experimental determinations by the TUNL group
in this threshold region; longitudinal, transverse, and interference response
functions measured in inclusive polarized electron scattering off polarized 3He
at excitation energies below the threshold for breakup into ppn, compared to
unpolarized longitudinal and transverse data from the Saskatoon group. The
calculations are based on a realistic Hamiltonian with two- and three-nucleon
interactions and a realistic current operator, including one- and two-body
components. The theoretical predictions obtained by including only one-body
currents are in violent disagreement with data. These differences between
theory and experiment are, to a large extent, removed when two-body currents
are taken into account, although some rather large discrepancies remain in the
c.m. energy range 0--100 keV, particularly for the pd differential cross
section and tensor analyzing power at small angles, and contributions to the
GDH integral. A rather detailed analysis indicates that these discrepancies
have, in large part, a common origin, and can be traced back to an excess
strength obtained in the theoretical calculation of the E1 reduced matrix
element associated with the pd channel having L,S,J=1,1/2,3/2. It is suggested
that this lack of E1 strength observed experimentally might have implications
for the nuclear interaction at very low energies. Finally, the validity of the
long-wavelength approximation for electric dipole transitions is discussed.


title: Parity splitting in the alternating parity bands of some actinide nuclei

abstract:
  An angular momentum dependence of the parity splitting in the alternating
parity bands of nuclei with strong octupole correlations is considered basing
on the model of the octupole motion in a one-dimensional potential well
conserving axial symmetry. A sign reversal of the parity splitting at higher
values of the angular momentum is interpreted as a result of the Coriolis
coupling to K=1 octupole mode. New experimental data on the spectra of the
alternating parity octupole bands are used.


title:
Pairing correlations in nuclear systems, from infinite matter to finite
  nuclei

abstract:
  Finite nuclei such as those found in the chain of even tin isotopes from
^{102}Sn to ^{130}Sn, exhibit a near constancy of the 2^+_1-0^+_1 excitation
energy, a constancy which can be related to strong pairing correlations and the
near degeneracy in energy of the relevant single particle orbits. Large
shell-model calculations for these isotopes reveal that the major contribution
to pairing correlations in the tin isotopes stems from the ^1S_0 partial wave
in the nucleon-nucleon interaction. Omitting this partial wave and the ^3P_2
wave in the construction of an effective interaction, results in a spectrum
which has essentially no correspondence with experiment. These partial wave are
also of importance for infinite neutron matter and nuclear matter and give the
largest contribution to the pairing interaction and energy gap in neutron star
matter.


title:
Spin-dependent correlations and the semi-exclusive ^{16}O(e,e'p)
  reaction

abstract:
  The effect of central, tensor and spin-isospin nucleon-nucleon correlations
upon semi-exclusive ^{16}O(e,e'p) reactions is studied for Q^2 and Bjorken x
values in the range $0.2 \lesssim Q^2 \lesssim 1.1 (GeV/c)^2$ and 0.15
$\lesssim$ x $\lesssim$ 2. The fully unfactorized calculations are performed in
a framework that accounts not only for the dynamical coupling of virtual
photons to correlated nucleon pairs but also for meson-exchange and
$\Delta_{33}$-isobar currents. Tensor correlations are observed to produce
substantially larger amounts of semi-exclusive ^{16}O(e,e'p) strength than
central correlations do and are predominantly manifest in the proton-neutron
knockout channel. With the exception of the $x \approx 2$ case, in all
kinematical situations studied the meson-exchange and isobar currents are a
strong source of A(e,e'p) strength at deep missing energies. This feature gives
the A(e,e'p) strength at deep missing energies a pronounced transverse
character.


title: Multiboson effects in multiparticle production

abstract:
  The influence of multiboson effects on pion multiplicities, single-pion
spectra and two-pion correlation functions is discussed in terms of an
analytically solvable model. The applicability of its basic factorization
assumption is clarified. An approximate scaling of the basic observables with
the phase space density is demonstrated in the low density (gas) limit. This
scaling and also its violation at high densities due to the condensate
formation is described by approximate analytical formulae which allow, in
principle, for the identification of the multiboson effects among others. For
moderate densities indicated by the experimental data, a fast saturation of
multiboson effects with the number of contributing cumulants is obtained,
allowing for the account of these effects in realistic transport code
simulations. At high densities, the spectra are mainly determined by the
universal condensate term and the initially narrow Poisson multiplicity
distribution approaches a wide Bose-Einstein one. As a result, the intercepts
of the inclusive and fixed-$n$ correlation functions (properly normalized to 1
at large relative momenta) approach 2 and 1, respectively and their widths
logarithmically increase with the increasing phase space density. It is shown
that the neglect of energy-momentum constraints in the model is justified
except near a multipion threshold, where these constraints practically exclude
the possibility of a very cold condensate production. It is argued that
spectacular multiboson effects are likely to be observed only in the rare
events containing sufficiently high density (speckle) fluctuations.


title:
Beyond the time independent mean field theory for nuclear and atomic
  reactions: Inclusion of particle-hole correlations in a generalized random
  phase approximation

abstract:
  The time independent mean field method (TIMF) for scattering defines
biorthonormal sets of single-particle wave functions and corresponding creation
and annihilation operators. 2p - 2h correlations can be introduced through a
generalized random phase approximation; 1p - 1h contributions vanish (Brillouin
theorem). While the general variational method for scattering by Giraud and
Nagarajan solves inhomogeneous Euler equations by inversion of the standard,
hermitean Hamiltonian, the present approach diagonalizes a non-hermitean
Hamiltonian, which carries the information about entrance and exit channels.


title: Statistical Theory of Parity Nonconservation in Compound Nuclei

abstract:
  We present the first application of statistical spectroscopy to study the
root-mean-square value of the parity nonconserving (PNC) interaction matrix
element M determined experimentally by scattering longitudinally polarized
neutrons from compound nuclei. Our effective PNC interaction consists of a
standard two-body meson-exchange piece and a doorway term to account for
spin-flip excitations. Strength functions are calculated using realistic
single-particle energies and a residual strong interaction adjusted to fit the
experimental density of states for the targets, ^{238} U for A\sim 230 and
^{104,105,106,108} Pd for A\sim 100. Using the standard Desplanques, Donoghue,
and Holstein estimates of the weak PNC meson-nucleon coupling constants, we
find that M is about a factor of 3 smaller than the experimental value for
^{238} U and about a factor of 1.7 smaller for Pd. The significance of this
result for refining the empirical determination of the weak coupling constants
is discussed.


title:
Isoscalar off-shell effects in threshold pion production from pd
  collisions

abstract:
  We test the presence of pion-nucleon isoscalar off-shell effects in the
$pd\to \pi^+ t$ reaction around the threshold region. We find that these
effects significantly modify the production cross section and that they may
provide the missing strength needed to reproduce the data at threshold.


title:
Brueckner Theory of Nuclear Matter with Nonnucleonic Degrees of Freedom
  and Relativity

abstract:
  For the past 40 years, Brueckner theory has proven to be a most powerful tool
to investigate systematically models for nuclear matter. I will give an
overview of the work done on nuclear matter theory, starting with the simplest
model and proceeding step by step to more sophisticated models by extending the
degrees of freedom and including relativity. The final results of a
comprehensive hadronic theory of nuclear matter are compared to the predictions
by currently fashionable two-nucleon force models. It turns out that a
two-nucleon force can, indeed, reproduce those results if the potential is
nonlocal, since nonlocality is an inherent quality of the more fundamental
fieldtheoretic approach. This nonlocality is crucial for creating sufficient
nuclear binding.


title: The $\Delta$-excitation in the nuclear charge longitudinal response

abstract:
  The presence of a resonant structure corresponding to the $\Delta$ excitation
in the longitudinal response to an e.m. probe is investigated. It is shown that
many-body effects could significantly increase the relativistic contribution
suggested by M.Ericson and coworkers


title: A System of Interest in Spectroscopy: The qp-Rotor System

abstract:
  A rotor system, having the symmetry afforded by the two-parameter quantum
algebra Uqp(u(2)), is investigated in this communication. This system is useful
in rotational spectroscopy of molecules and nuclei. In particular, it is shown
to lead to a model (viz., the qp-rotor model) for describing (via an energy
formula and a qp-deformation of E2 reduced transition probabilities) rotational
bands of deformed and superdeformed nuclei.


title: Nuclear Skins and Halos in the Mean-Field Theory

abstract:
  Nuclei with large neutron-to-proton ratios have neutron skins, which manifest
themselves in an excess of neutrons at distances greater than the radius of the
proton distribution. In addition, some drip-line nuclei develop very extended
halo structures. The neutron halo is a threshold effect; it appears when the
valence neutrons occupy weakly bound orbits. In this study, nuclear skins and
halos are analyzed within the self-consistent Skyrme-Hartree-Fock-Bogoliubov
and relativistic Hartree-Bogoliubov theories for spherical shapes. It is
demonstrated that skins, halos, and surface thickness can be analyzed in a
model-independent way in terms of nucleonic density form factors. Such an
analysis allows for defining a quantitative measure of the halo size. The
systematic behavior of skins, halos, and surface thickness in even-even nuclei
is discussed.


title: Origin of Relativistic Effects in the Reaction D(e,e'p)n at GeV Energies

abstract:
  In a series of recent publications, a new approach to the non-relativistic
reduction of the electromagnetic current operator in calculations of
electro-nuclear reactions has been introduced. In one of these papers, the
conjecture that at energies of a few GeV, the bulk of the relativistic effects
comes from the current and not from the nuclear dynamics was made, based on the
large relativistic effects in the transverse-longitudinal response. Here, we
explicitly compare a fully relativistic, manifestly covariant calculation
performed with the Gross equation, with a calculation that uses a
non-relativistic wave function and a fully relativistic current operator. We
find very good agreement up to missing momenta of 400 MeV/c, thus confirming
the previous conjecture. We discuss slight deviations in cross sections for
higher missing momenta and their possible origin, namely p-wave contributions
and off-shell effects.


title: Prompt Contributions to the Dilepton Yield in Heavy Ion Collisions

abstract:
  The mass spectrum is calculated for those dileptons which are produced in the
early phase of a heavy ion collisions via the direct production NN ->
(l^+)(l^-)X and via the Compton process GN -> (l^+)(l^-)X with prompt gluons
radiated in preceding NN interactions. Both mechanisms produce a mass spectrum
which decreases steeply with invariant mass of the l^+l^- pair and which is
below the CERES data for Pb-Au collisions by about one order of magnitude.


title: Scaling law for the electromagnetic form factors of the proton

abstract:
  The violation of the scaling law for the electric and magnetic form factors
of the proton are examined within the cloudy bag model. The suppression of the
ratio of the electric and magnetic form factors is natural in the bag model.
The pion cloud plays a moderate role in understanding the recent data from
TJNAF.


title:
alpha-decay chains of Z=114, A=289 and Z=118, A=293 in the relativistic
  mean-field model

abstract:
  A comparison of calculated and experimental Q_alpha values of superheavy
even-even nuclei and a few selected odd-N nuclei is presented in the framework
of the relativistic mean-field model with the parameterization NL-Z2. Blocking
effects are found to be important for a proper description of Q_alpha of odd
mass nuclei. The model gives a good overall description of the available
experimental data. The mass and charge assignment of the recently measured
decay chains from Dubna and Berkeley is in agreement with the predictions of
the model. The analysis of the new data does not allow a final conclusion about
the location of the expected island of spherical doubly-magic superheavy
nuclei.


title: Band structure from random interactions

abstract:
  The anharmonic vibrator and rotor regions in nuclei are investigated in the
framework of the interacting boson model using an ensemble of random one- and
two-body interactions. We find a predominance of L(P)=0(+) ground states, as
well as strong evidence for the occurrence of both vibrational and rotational
band structures. This remarkable result suggests that such band structures
represent a far more general (robust) property of the collective model space
than is generally thought.


title: Selected nucleon form factors and a composite scalar diquark

abstract:
  A covariant, composite scalar diquark, Fadde'ev amplitude model for the
nucleon is used to calculate pseudoscalar, isoscalar- and isovector-vector,
axial-vector and scalar nucleon form factors. The last yields the nucleon
sigma-term and on-shell sigma-nucleon coupling. The calculated form factors are
soft, and the couplings are generally in good agreement with experiment and
other determinations. Elements in the dressed-quark-axial-vector vertex that
are not constrained by the Ward-Takahashi identity contribute ~20% to the
magnitude of g_A. The calculation of the nucleon sigma-term elucidates the only
unambiguous means of extrapolating meson-nucleon couplings off the meson
mass-shell.


title: Exotic Stochastic Processes from Complex Quantum Environments

abstract:
  Stochastic processes are shown to emerge from the time evolution of complex
quantum systems. Using parametric, banded random matrix ensembles to describe a
quantum chaotic environment, we show that the dynamical evolution of a particle
coupled to such environments displays a variety of stochastic behaviors,
ranging from turbulent diffusion to L\'evy processes and Brownian motion.
Dissipation and diffusion emerge naturally in the stochastic interpretation of
the dynamics. This approach provides a derivation of a fractional kinetic
theory in the classical limit and leads to classical L\'evy dynamics.


title:
Do Rotational Bands Extend Beyond the Shell Model Limit - The Strange
  Case of the J=6^{+}_{1} in ^{8}Be

abstract:
  This paper has been withdrawn by the authors as we await a larger model space
calculation.


title:
One-loop calculations of hyperon polarizabilities under the large N_c
  consistency condition

abstract:
  The spin-averaged electromagnetic polarizabilities of the hyperons $\Lambda$
and $\Sigma$ are calculated within the one-loop approximation by use of the
dispersion theory. The photon and meson couplings to hyperons are determined so
as to satisfy the large N_c consistency condition. It is shown that in order
for the large N_c consistency condition to hold exotic hyperon states such as
$\Sigma^{**}$ with I=2 and J=3/2 are required in the calculation of the
magnetic polarizability of the $\Sigma$ state.


title:
The Impact of Isospin Breaking on the Distribution of Transition
  Probabilities

abstract:
  In the present paper we investigate the effect of symmetry breaking in the
statistical distributions of reduced transition amplitudes and reduced
transition probabilities. These quantities are easier to access experimentally
than the components of the eigenvectors and were measured by Adams et al. for
the electromagnetic transitions in ^{26}Al. We focus on isospin symmetry
breaking described by a matrix model where both, the Hamiltonian and the
electromagnetic operator, break the symmetry. The results show that for partial
isospin conservation, the statistical distribution of the reduced transition
probability can considerably deviate from the Porter-Thomas distribution.


title: Magnetic Oscillations in the Nambu - Jona-Lasinio model

abstract:
  The phase structure of a simple Nambu-Jona-Lasinio model has been
investigated at non-zero values of $\mu$ and H, where H is an external magnetic
field and $\mu$ is the chemical potential. On this basis magnetic oscillations
effects were considered. It was shown that there are standard (periodic) van
Alphen-de Haas magnetic oscillations of some thermodynamical quantities,
including magnetization, pressure and particle density in the NJL system.
Besides, we have found non-standard, i.e. non-periodic, magnetic oscillations,
since the frequency of oscillations is a H-dependent quantity. Finally, there
arises an oscillating behaviour not only for thermodynamical quantities, but
also for a dynamical quantity like the quark mass. The possibility for magnetic
oscillations of some physical quantities inside neutron stars is discussed.


title: Quarks and Neutron Halo Nuclei, Nuclear Clusters and Nuclear Molecules

abstract:
  It is shown that the hole in the centre of $ ^{3}H $, $ ^{3}He $ and $ ^{4}He
$, the neutron halos in nuclei, the $ \alpha - $ and other clustering effects
in nuclei and the nuclear molecules all basically arise due to the same
underlying effect. We shall show that all these ground state properties of
nuclei are manifestations of quark effects. The role of triton clustering in
very neutron rich nuclei is emphasized. All these require the concept of hidden
colour states which arise from confinement ideas of QCD for the multi-quark
systems. This provides comprehensive understanding of diverse nuclear effects
and makes unique predictions.


title: Twenty-Five Years of Progress in the Three-Nucleon Problem

abstract:
  Twenty-five years ago the International Few-Body Conference was held in
Quebec City. It became very clear at that meeting that the theoretical
situation concerning the He3 and H3 ground states was confused. A lack of
computational power prevented converged brute-force solutions of the Faddeev or
Schroedinger equations, both for bound and continuum states of the
three-nucleon systems. Pushed by experimental programs at Bates and elsewhere
and facilitated by the rapid growth of computational power, converged solutions
were finally achieved about a decade later. Twenty-five years ago the first
three-nucleon force based on chiral-symmetry considerations was produced. Since
then this symmetry has been our guiding principle in constructing three-nucleon
forces and, more recently, nucleon-nucleon forces. We are finally nearing an
understanding of the common ingredients used in constructing both types of
forces. I will discuss these and other issues involving the few-nucleon systems
and attempt to define the current state-of-the-art.


title: The role of S_11 resonance in pi N Scattering

abstract:
  We analyze Pion Nucleon Scattering up to 700 MeV using a simple,
relativistic, unitary model\cite{1}. The kernel of the integral equation
includes nucleon, roper, delta, D_13 as well as S_11 poles with their
corresponding crossed pole terms approximated by contact interactions. The s-
and p- wave phase shifts are calculated from the model and shown to agree very
well with the values derived from pi N scattering data \cite {2}. All
parameters which involve S_{11} are presented.


title: Diffusion over a saddle with a Langevin equation

abstract:
  The diffusion problem over a saddle is studied using a multi-dimensional
Langevin equation. An analytical solution is derived for a quadratic potential
and the probability to pass over the barrier deduced. A very simple solution is
given for the one dimension problem and a general scheme is shown for higher
dimensions.


title:
Isotopic dependence of fusion cross sections in reactions with heavy
  nuclei

abstract:
  The dependence of fusion cross section on the isotopic composition of
colliding nuclei is analysed within the dinuclear system concept for compound
nucleus formation. Probabilities of fusion and surviving probabilities,
ingredients of the evaporation residue cross sections, depend decisively on the
neutron numbers of the dinuclear system. Evaporation residue cross sections for
the production of actinides and superheavy nuclei, listed in table form, are
discussed and compared with existing experimental data. Neutron-rich
radioactive projectiles are shown to lead to similar fusion cross sections as
stable projectiles.


title: SU(3) realization of the rigid asymmetric rotor within the IBM

abstract:
  It is shown that the spectrum of the asymmetric rotor can be realized quantum
mechanically in terms of a system of interacting bosons. This is achieved in
the SU(3) limit of the interacting boson model by considering higher-order
interactions between the bosons. The spectrum corresponds to that of a rigid
asymmetric rotor in the limit of infinite boson number.


title: What is the structure of the Roper resonance?

abstract:
  We investigate the structure of the nucleon resonance N^*(1440) (Roper)
within a coupled-channel meson exchange model for pion-nucleon scattering. The
coupling to pipiN states is realized effectively by the coupling to the sigmaN,
piDelta and rhoN channels. The interaction within and between these channels is
derived from an effective Lagrangian based on a chirally symmetric Lagrangian,
which is supplemented by well known terms for the coupling of the Delta isobar,
the omega meson and the 'sigma', which is the name given here to the strong
correlation of two pions in the scalar-isoscalar channel. In this model the
Roper resonance can be described by meson-baryon dynamics alone; no genuine
N^*(1440) (3 quark) resonance is needed in order to fit piN phase shifts and
inelasticities.


title:
Self-consistent theory of large amplitude collective motion:
  Applications to approximate quantization of non-separable systems and to
  nuclear physics

abstract:
  The goal of the present account is to review our efforts to obtain and apply
a ``collective'' Hamiltonian for a few, approximately decoupled, adiabatic
degrees of freedom, starting from a Hamiltonian system with more or many more
degrees of freedom. The approach is based on an analysis of the classical limit
of quantum-mechanical problems. Initially, we study the classical problem
within the framework of Hamiltonian dynamics and derive a fully self-consistent
theory of large amplitude collective motion with small velocities. We derive a
measure for the quality of decoupling of the collective degree of freedom. We
show for several simple examples, where the classical limit is obvious, that
when decoupling is good, a quantization of the collective Hamiltonian leads to
accurate descriptions of the low energy properties of the systems studied. In
nuclear physics problems we construct the classical Hamiltonian by means of
time-dependent mean-field theory, and we transcribe our formalism to this case.
We report studies of a model for monopole vibrations, of $^{28}$Si with a
realistic interaction, several qualitative models of heavier nuclei, and
preliminary results for a more realistic approach to heavy nuclei. Other topics
included are a nuclear Born-Oppenheimer approximation for an {\em ab initio}
quantum theory and a theory of the transfer of energy between collective and
non-collective degrees of freedom when the decoupling is not exact. The
explicit account is based on the work of the authors, but a thorough survey of
other work is included.


title: Single Boson Images Via an Extended Holstein Primakoff Mapping

abstract:
  The Holstein-Primakoff mapping for pairs of bosons is extended in order to
accommodate single boson mapping. The proposed extension allows a variety of
applications and especially puts the formalism at finite temperature on firm
grounds. The new mapping is applied to the O(N+1) anharmonic oscillator with
global symmetry broken down to O(N). It is explicitly demonstrated that
N-Goldstone modes appear. This result generalizes the Holstein-Primakoff
mapping for interacting boson as developed in ref.[1].


title: Neutron Stars: Recent Developments

abstract:
  Recent developments in neutron star theory and observation are discussed.
Based on modern nucleon-nucleon potentials more reliable equations of state for
dense nuclear matter have been constructed. Furthermore, phase transitions such
as pion, kaon and hyperon condensation, superfluidity and quark matter can
occur in cores of neutron stars. Specifically, the nuclear to quark matter
phase transition and its mixed phases with intriguing structures is treated.
Rotating neutron stars with and without phase transitions are discussed and
compared to observed masses, radii and glitches. The observations of possible
heavy $\sim 2M_\odot$ neutron stars in X-ray binaries and QPO's require
relatively stiff equation of states and restrict strong phase transitions to
occur at very high nuclear densities only.


title: Comment on "Nucleon form factors and a nonpointlike diquark"

abstract:
  Authors of Phys. Rev. C 60, 062201 (1999) presented a calculation of the
electromagnetic form factors of the nucleon using a diquark ansatz in the
relativistic three-quark Faddeev equations. In this Comment it is pointed out
that the calculations of these form factors stem from a three-quark bound state
current that contains overcounted contributions. The corrected expression for
the three-quark bound state current is derived.


title: Many-body corrections to the nuclear anapole moment II

abstract:
  The contribution of many-body effects to the nuclear anapole moment were
studied earlier in [1]. Here, more accurate calculation of the many-body
contributions is presented, which goes beyond the constant density
approximation for them used in [1]. The effects of pairing are now included.
The accuracy of the short range limit of the parity violating nuclear forces is
discussed.


title: Tensor correlations in nuclei and exlusive electron scattering

abstract:
  The effect of tensor nucleon-nucleon correlations upon exclusive and
semi-exclusive electronuclear reactions is studied. Differential cross sections
for the semi-exclusive ^{16}O(e,e'p) and exclusive ^{16}O(e,e'pn) processes are
computed by explicitly evaluating the dynamical electromagnetic coupling to a
tensor correlated nucleon pair. In both reaction channels the tensor
correlations contribute in a very substantial way. Tensor correlations are
found to generate more electronuclear strength than central Jastrow
correlations do.


title: Quadrupole Pairing Interaction and Signature Inversion

abstract:
  The signature inversion in the \pi h11/2 \otimes \nu h11/2 rotational bands
of odd-odd Cs and La isotopes and the \pi h11/2 \otimes \nu i13/2 bands of
odd-odd Tb, Ho and Tm nuclei is investigated using pairing and deformation self
consistent mean field calculations. The model can rather satisfactorily account
for the anomalous signature splitting, provided that spin assignments in som of
the bands are revised. Our calculations show that signature inversioncan appear
already at axially symmetric shapes. It is found that this is due to the
contribution of the \lambda\mu=22 component of the quadrupole pairing
interaction to the mean field potential.


title: T=0 Neutron-Proton Correlations at High Angular Momenta

abstract:
  The properties of T=0 neutron-proton correlations are discussed within the
frame work of different model calculations. Single-j shell calculations reveal
that the T=0 correlations remain up to the highest frequencies. They are more
complex and cannot be restricted to L=0 pairs only. Whereas it may be difficult
to find clear evidence for T=0 pairing at low spins, T=0 correlations are found
to induce a new excitation scheme at high angular momenta.


title: Nuclear disintegration induced by virtual photons at heavy-ion colliders

abstract:
  A model of electromagnetic interaction of relativistic heavy ions which makes
it possible to calculate the inclusive and exclusive characteristics of such
interactions is presented. The multistep model includes (1) the single and
double virtual photon absorption by a nucleus, (2) intranuclear cascades of
produced hadrons and (3) statistical decay of excited residual nuclei described
by evaporation, fission and multifragmentation mechanisms. Components of the
model were verified by comparison of calculation results with experimental data
obtained with monoenergetic photons and heavy ions at KEK-Tanashi Synchrotron
and CERN SPS accelerator, respectively.


title: Recent Results from Jefferson Lab

abstract:
  Recent results on studies of the structure of nucleons and nuclei in the
regime of strong interaction QCD are discussed. Use of high current polarized
electron beams, polarized targets, and recoil polarimeters, in conjunction with
modern spectrometers and detector instrumentation allow much more detailed
studies of nucleon and nuclear structure than has been possible in the past.
The CEBAF accelerator at Jefferson Lab was build to study the internal
structure of hadrons in a regime where confinement is important and strong
interaction QCD is the relevant theory. I discuss how the first experiments
already make significant contributions towards an improved understanding of
hadronic structure.


title:
Unusual statistics of interference effects in neutron scattering from
  compound nuclei

abstract:
  We consider interference effects between p-wave resonance scattering
amplitude and background s-wave amplitude in low-energy neutron scattering from
a heavy nucleus which goes through the compound nucleus stage. The first effect
is in the difference between the forward and backward scattering cross
sections. Because of the chaotic nature of the compound states, this effect is
a random variable with zero mean. However, a statistical consideration shows
that the probability distribution of this effect does not obey the standard
central limit theorem. That is, the probability density for the effect averaged
over n resonances does not become a Gaussian distribution with the variance
decreasing as 1/sqrt(n) (``violation'' of the theorem!). We derive the
probability distribution of the effect and the limit distribution of the
average. It is found that the width of this distribution does not decrease with
the increase of n, i.e., fluctuations are not suppressed by averaging.
Furthermore, we consider the correlation between the neutron spin and the
scattering plane and find that this effect, although much smaller, shows
fluctuations which actually increase upon averaging over many measurements.
Limits of the effects due to finite resonance widths are also considered. In
the appendix we present a simple derivation of the limit theorem for the
average of random variables with infinite variances.


title: An Isobaric Model for Kaon photoproduction

abstract:
  The kaon photoproduction is analyzed up to $E_\gamma^{\rm Lab}$=2.0 GeV by
using an isobaric model based on effective Lagrangians and by taking a cross
symmetry into account. Both {\it pseudovector} and {\it pseudoscalar} couplings
for kaon-baryon-baryon (baryon spin=1/2) interactions are considered with form
factors. A vector meson($K^*(890)$), an axial vector meson($K_1(1270)$),
nucleon resonances($J\le5/2$), and hyperon resonances($J\le3/2$) are treated as
participating particles. By determining unknown coupling constants through a
systematic fitting of the differential cross section, the total cross section,
the single polarization observable, and the radiative kaon capture branching
ratio to their experimental data, we find out a simple model which reproduces
all the experimental data well.


title:
Pion Scalar Density and Chiral Symmetry Restoration at Finite
  Temperature and Density

abstract:
  This paper is devoted to the evaluation of the pionic scalar density at
finite temperature and baryonic density. We express the latter effect in terms
of the nuclear response evaluated in the random phase approxima- tion. We
discuss the density and temperature evolution of the pionic density which
governs the quark condensate evolution. Numerical evalua- tions are performed.


title: Effects of HBT correlations on flow measurements

abstract:
  The methods currently used to measure collective flow in nucleus--nucleus
collisions assume that the only azimuthal correlations between particles are
those arising from their correlation with the reaction plane. However, quantum
HBT correlations also produce short range azimuthal correlations between
identical particles. This creates apparent azimuthal anisotropies of a few
percent when pions are used to estimate the direction of the reaction plane.
These should not be misinterpreted as originating from collective flow. In
particular, we show that the peculiar behaviour of the directed and elliptic
flow of pions observed by NA49 at low p_T can be entirely understood in terms
of HBT correlations. Such correlations also produce apparent higher Fourier
harmonics (of order n larger than 3) of the azimuthal distribution, with
magnitudes of the order of 1%, which should be looked for in the data.


title: The directed flow maximum near c_s=0

abstract:
  We investigate the excitation function of quark-gluon plasma formation and of
directed in-plane flow of nucleons in the energy range of the BNL-AGS and for
the E(Lab)=40AGeV Pb+Pb collisions performed recently at the CERN-SPS. We
employ the three-fluid model with dynamical unification of kinetically
equilibrated fluid elements. Within our model with first-order phase transition
at high density, droplets of QGP coexisting with hadronic matter are produced
already at BNL-AGS energies, E(Lab)=10AGeV. A substantial decrease of the
isentropic velocity of sound, however, requires higher energies, E(Lab)=40AGeV.
We show the effect on the flow of nucleons in the reaction plane. According to
our model calculations, kinematic requirements and EoS effects work
hand-in-hand at E(Lab)=40AGeV to allow the observation of the dropping velocity
of sound via an increase of the directed flow around midrapidity as compared to
top BNL-AGS energy.


title:
Pion and Kaon Electromagnetic Form Factors in a $SU_{L}(3)\otimes
  SU_{R}(3)$ Effective Lagrangian

abstract:
  A SU(2) effective lagrangian is extended to a $SU_{L}(3)\otimes SU_{R}(3)$ by
including the vector and axial vector meson. With this effective lagrangian,
electromagnetic form factors of charged pion and kaon are calculated. The
pseudoscalar meson loops are taken into account. Good agreement with
experimental data is obtained for those form factors. Decay widths of $\rho\to
\pi\pi$ and $\phi\to K^{+}K^{-}$ are also calculated and shown to agree with
experimental data very well.


title: Properties of \beta-stable neutron star matter with hyperons

abstract:
  We present results from many-body calculations for \beta-stable neutron star
matter with nucleonic and hyperonic degrees of freedom, employing the most
recent parametrizations of the baryon-baryon interaction of the Nijmegen group.
It is found that the only strange baryons emerging in \beta-stable matter up to
total baryonic densities of 1.2 fm^{-3} are \Sigma^- and \Lambda. The
corresponding equations of state are thence used to compute properties of
neutron stars such as the masses, moments of inertia and radii. We also study
the possibility of forming a hyperon superfluid and discuss its implications
for neutron stars.


title: The Role of Meson Retardation in the NN Interaction above Pion Threshold

abstract:
  A model is developed for the hadronic interaction in the two-nucleon system
above pion threshold which is based on meson, nucleon and $\Delta$ degrees of
freedom and which includes full meson retardation in the exchange operators.
For technical reasons, the model allows maximal one meson to be present
explicitly. Thus the Hilbert space contains besides $NN$ and $N\Delta$ also
configurations consisting of two nucleons and one meson. For this reason, only
two- and three-body unitarity is obeyed, and the model is suited for reactions
in the two nucleon sector only, where one pion is produced or absorbed.
Starting from a realistic pure nucleonic retarded potential, which had to be
renormalized because of the additional $\pi$ and $\Delta$ degrees of freedom, a
reasonable fit to experimental $NN$-scattering data could be achieved.


title:
Positivity restrictions in polarized coincidence electronuclear
  scattering

abstract:
  We make a systematic examination of the role played by the restriction that
the cross section in polarized coincidence electronuclear processes must be
positive. The necessary formalism for unpolarized scattering structure
functions is developed within two frameworks: (i) the response tensor method;
and (ii) the Jacob-Wick method. Equivalence of the two methods is demonstrated
for unpolarized scattering, and then the simpler Jacob-Wick method is applied
to the polarized pseudoscalar electroproduction off a nucleon. We derive three
known and eight new inequalities among the polarized target structure
functions, as well as eleven new polarized ejectile structure functions
inequalities. We also provide rules for this method to be used in deuteron
two-body electrodisintegration in conjunction with the results published in
Phys. Rev. C 40, 2479 (1989).


title: What is the Physics behind the 3He-4He Anomaly ?

abstract:
  We show that coalescence of nucleons emitted prior to thermalization in
highly excited nuclei can explain the anomaly of kinetic energies of helium
clusters. A new coalescence algorithm has been included into the statistical
approach to nuclear reactions formerly used to describe intermediate mass
fragment production.


title:
Local realizations of contact interactions in two- and three-body
  problems

abstract:
  Mathematically rigorous theory of the two-body contact interaction in three
dimension is reviewed. Local potential realizations of this proper contact
interaction are given in terms of Poschl-Teller, exponential and square-well
potentials. Three body calculation is carried out for the halo nucleus 11Li
using adequately represented contact interaction.


title:
Fine Structure in the Decay of Deformed Proton Emitters: Non-adiabatic
  Approach

abstract:
  The coupled-channel Schrodinger equation with outgoing wave boundary
conditions is employed to study the fine structure seen in the proton decay of
deformed even-N, odd-Z rare earth nuclei 131-Eu and 141-Ho. Experimental
lifetimes and proton-decay branching ratios are reproduced. The comparison with
the standard adiabatic theory is made.


title: Meson-baryon interaction in the quark-gluon exchange framework

abstract:
  We extend the Fock-Tani formalism to include the meson-baryon interaction.
The Fock-Tani formalism is a first principle method which allows the use of
field theoretic methods for treating systems of composite particles. An
application of this general result can be the $K^{+}N$ system which is now
reconized as much more suitable system for the investigation of the short range
nature of the hadronic repulsion.


title: Ground state correlations and mean-field in $^{16}$O: Part II

abstract:
  We continue the investigations of the $^{16}$O ground state using the
coupled-cluster expansion [$\exp({\bf S})$] method with realistic nuclear
interaction. In this stage of the project, we take into account the three
nucleon interaction, and examine in some detail the definition of the internal
Hamiltonian, thus trying to correct for the center-of-mass motion. We show that
this may result in a better separation of the internal and center-of-mass
degrees of freedom in the many-body nuclear wave function. The resulting ground
state wave function is used to calculate the "theoretical" charge form factor
and charge density. Using the "theoretical" charge density, we generate the
charge form factor in the DWBA picture, which is then compared with the
available experimental data. The longitudinal response function in inclusive
electron scattering for $^{16}$O is also computed.


title:
Three-body matrix elements for calculations of mean field and exp(S)
  ground sate correlations

abstract:
  In this document we present our approach to the computation of three-body
matrix elements, based on the Urbana family of three-nucleon potentials. The
calculations refer only to the necessary matrix elements needed to include the
three-nucleon interaction in the manner presented in nucl-th/9912023.


title:
Coulomb corrections to low energy antiproton annihilation cross sections
  on protons and nuclei

abstract:
  We calculate, in a systematic way, the enhancement effect on
antiproton-proton and antiproton-nucleus annihilation cross sections at low
energy due to the initial state electrostatic interaction between the
projectile and the target nucleus. This calculation is aimed at future
comparisons between antineutron and antiproton annihilation rates on different
targets, for the extraction of pure isospin channels.


title:
Chiral unitary meson-baryon dynamics in the presence of resonances:
  Elastic pion-nucleon scattering

abstract:
  We develop a novel approach to chiral meson-baryon dynamics incorporating
unitarity constraints and explicit resonance fields. It is based on the most
general structure of any pion-nucleon partial wave amplitude neglecting the
unphysical cuts as derived from the N/D method. This amplitude is then matched
to the one-loop heavy baryon chiral perturbation theory result at third order
and to tree level exchanges of baryon- and meson states in the s,t and u
channels. This generates the left-hand cuts. The unitarization procedure does
not involve form factors or regulator functions. The resonance parameters are
determined from fits to the S- and P-wave pion-nucleon partial wave amplitudes
for energies up to 1.3 GeV. In particular, the $\Delta (1232)$ is accurately
reproduced whereas scalar and vector meson couplings are less precisely pinned
down. We also obtain a satisfactory description of the $\pi$N threshold
parameters. Further extensions of this method to coupled channels and the
three-flavor case are briefly discussed.


title: Determination of the Mean-Field Momentum-Dependence using Elliptic Flow

abstract:
  Midrapidity nucleon elliptic flow is studied within the Boltzmann-equation
simulations of symmetric heavy-ion collisions. The simulations follow a lattice
Hamiltonian extended to relativistic transport. It is demonstrated that in the
peripheral heavy-ion collisions the high-momentum elliptic flow is strongly
sensitive to the momentum dependence of mean field at supranormal densities.
The high transverse-momentum particles are directly and exclusively emitted
from the high-density zone in the collisions, while remaining particles
primarily continue along the beam axis. The elliptic flow was measured by the
KaoS Collaboration as a function of the transverse momentum at a number of
impact parameters in Bi + Bi collisions at 400, 700, and 1000 MeV/nucleon. The
observed elliptic anisotropies in peripheral collisions, which quickly rise
with momentum, can only be explained in simulations when assuming a strong
momentum dependence of nucleonic mean field. This momentum dependence must
strengthen with the rise of density above normal. The mean-field
parametrizations, which describe the data in simulations with various success,
are confronted with mean fields from microscopic nuclear-matter calculations.
Two of the microscopic potentials in the comparisons have unacceptably weak
momentum-dependencies at supranormal densities. The optical potentials from the
Dirac-Brueckner-Hartree-Fock calculations, on the other hand, together with the
UV14 + TNI potential from variational calculations, agree rather well within
the region of sensitivity with the parametrized potentials that best describe
the data.


title:
Effect of nuclear deformation on J/Psi suppression in relativistic
  nucleus-nucleus collisions

abstract:
  Using a hadron-string cascade model, JPCIAE, we study the effect of nuclear
deformation on J/Psi suppression in the collision of uranium nuclei at 200A
GeV/c. We find that the J/Psi survival probability is much smaller if the major
axes of both deformed nuclei are along the beam direction than if they are
perpendicular to the beam direction.


title:
Nuclear symmetry energy in presence of hyperons in the nonrelativistic
  Thomas-Fermi approximation

abstract:
  We generalise the finite range momentum and density dependent
Seyler-Blanchard nucleon-nucleon effective interaction to the case of
interaction between two baryons. This effective interaction is then used to
describe dense hadronic matter relevant to neutron stars in the nonrelativistic
Thomas-Fermi approach. We investigate the behaviour of nuclear symmetry energy
in dense nuclear and hyperon matter relevant to neutron stars. It is found that
the nuclear symmetry energy always increases with density in hyperon matter
unlike the situation in nuclear matter. This rising characteristic of the
symmetry energy in presence of hyperons may have significant implications on
the mass-radius relationship and the cooling properties of neutron stars. We
have also noted that with the appearance of hyperons, the equation of state
calculated in this model remains causal at high density.


title:
Low- and intermediate-energy nucleon-nucleon interactions and the
  analysis of deuteron photodisintegration within the dispersion relation
  technique

abstract:
  The nucleon-nucleon interaction in the region of the nucleon kinetic energy
up to 1000 MeV is analysed together with the reaction $\gamma d \to pn$ in the
photon energy range $E_{\gamma}=0-400$ MeV. Nine nucleon-nucleon $s$-channel
partial amplitudes are reconstructed in the dispersion relation $N/D$ method:
$^1S_0$, $^3S_1-^3D_1$, $^3P_0$, $^1P_1$, $^3P_1$, $^3P_2$, $^1D_2$, $^3D_2$
and $^3F_3$. Correspondingly, the dispersive representation of partial
amplitudes $N\Delta \to pn$, $NN^* \to pn$ and $NN\pi \to pn$ is given. Basing
on that, we have performed parameter-free calculation of the amplitude $\gamma
d \to pn$, taking into account: $(i)$ pole diagram, $(ii)$ nucleon-nucleon
final-state rescattering $\gamma d \to pn \to pn$, and $(iii)$ inelastic
final-state rescatterings $\gamma d \to N\Delta(1232) \to pn$, $\gamma d \to
NN^*(1400) \to pn$ and $\gamma d \to NN\pi \to pn$. The $\gamma d \to pn$
partial amplitudes for nine above-mentioned channels are found. It is shown
that the process $\gamma d \to pn \to pn$ is significant for the waves $^1S_0$,
$^3P_0$, $^3P_1$, at $E_{\gamma} =50 -100$ MeV, while $\gamma d \to N\Delta \to
pn$ for the waves $^3P_2$, $^1D_2$,$^3F_3$ dominates at $E_{\gamma} > 300$ MeV.
Meson exchange current contributions into the deuteron disintegration are
estimated: they are significant at $E_\gamma =100-400$ MeV.


title:
Coulomb Corrections to Elastic Electron-Proton Scattering and the Proton
  Charge Radius

abstract:
  Recent values of the proton charge radius derived from the Lamb shift in
electronic hydrogen tend to be larger than those from electron scattering.
Therefore low-momentum-transfer scattering data from different groups and
laboratories have been reanalyzed with Coulomb and recoil corrections included.
This was done by calculating at each scattering angle and scattering energy the
corresponding correction obtained from a partial wave program which includes
recoil approximately. Corrections due to magnetic scattering were also made
before the rms-radius was determined by a fit which allows free normalization
for each experiment. It is shown that an analysis of electron scattering data
including Coulomb corrections lowers the $\chi^2$ of the fit and increases the
proton radius by about (0.008 - 0.013) fm depending on the fit strategy. A
value of r_p = 0.880 (15) fm is obtained which is in good agreement with the
one extracted from Lamb shift measurements.


title:
On the Delta-Delta component of the deuteron in the relativistic field
  theory model of the deuteron

abstract:
  The Delta-Delta component of the deuteron, where Delta stands for the
Delta(1232) resonance, is calculated in the relativistic field theory model of
the deuteron. For the probability of the Delta-Delta component of the deuteron
we give P(Delta-Delta) = 0.08 %. This prediction agrees good with the
experimental estimate P(Delta-Delta) < 0.4 % at 90 % of CL (D. Allasia et al.,
Phys. Lett. B174 (1986) 450).


title: On neutral pion electroproduction off deuterium

abstract:
  Threshold neutral pion electroproduction on the deuteron is studied in the
framework of baryon chiral perturbation theory at next-to-leading order in the
chiral expansion. To this order in small momenta, the amplitude is finite and a
sum of two- and three-body interactions with no undetermined parameters. We
calculate the S-wave multipoles for threshold production and the deuteron
S-wave cross section as a function of the photon virtuality. We also discuss
the sensitivity to the elementary neutron amplitudes.


title:
New Result for the Pion-Nucleon Sigma Term from an Updated VPI/GW
  Pion-Nucleon Partial-Wave and Dispersion Relation Analysis

abstract:
  A new result for the nucleon sigma term from an updated pion-nucleon
partial-wave and dispersion relation analysis of the Virginia Polytechnic
Institute (now George Washington University) group is discussed. Using a method
similar to that of Gasser, Leutwyler, Locher, and Sainio, we obtain Sigma=90
+/- 8 MeV (preliminary), in disagreement with the canonical result 64 +/- 8
MeV, but consistent with expectations based on new information on the $\pi$NN
coupling constant, pionic atoms, and the Delta resonance width.


title: A composite bosons minimal basis for the pairing Hamiltonian

abstract:
  The pairing interaction among identical nucleons in a single-particle level
is treated in the hamiltonian formalism using even Grassmann variables. A
minimal (irreducible) basis having a remarkable symmetry property is set up
using composite, commuting variables with a finite index of nilpotency.
Eigenvalues and eigenfunctions of given energy, seniority and zero third
component of the angular momentum of the pairing hamiltonian are then found.
The eigenvectors, which cannot be cast solely in terms of composite bosons with
angular momentum zero and two, are expanded in the minimal basis with
coefficients analytically expressed in terms of a generalized hypergeometric
function.


title:
Quantum Statistical Model of Nuclear Multifragmentation in the Canonical
  Ensemble Method

abstract:
  A quantum statistical model of nuclear multifragmentation is proposed. The
recurrence equation method used within the canonical ensemble makes the model
solvable and transparent to physical assumptions and allows to get results
without involving the Monte Carlo technique. The model exhibits the first order
phase transition. Quantum statistics effects are clearly seen on the
microscopic level of occupation numbers but are almost washed out for global
thermodynamic variables and the averaged observables studied. In the latter
case, the recurrence relations for multiplicity distributions of both
intermediate-mass and all fragments are derived and the specific changes in the
shape of multiplicity distributions in the narrow region of the transition
temperature is stressed. The temperature domain favorable to search for the HBT
effect is noted.


title:
An investigation of standard thermodynamic quantities as determined via
  models of nuclear multifragmentation

abstract:
  Both simple and sophisticated models are frequently used in an attempt to
understand how real nuclei breakup when subjected to large excitation energies,
a process known as nuclear multifragmentation. Many of these models assume
equilibriumthermodynamics and produce results often interpreted as evidence of
a phase transition. This work examines one class of models and employs standard
thermodynamical procedure to explore the possible existence and nature of a
phase transition. The role of various terms, e.g. Coulomb and surface energy,
is discussed.


title: Parity Violating Measurements of Neutron Densities

abstract:
  Parity violating electron nucleus scattering is a clean and powerful tool for
measuring the spatial distributions of neutrons in nuclei with unprecedented
accuracy. Parity violation arises from the interference of electromagnetic and
weak neutral amplitudes, and the $Z^0$ of the Standard Model couples primarily
to neutrons at low $Q^2$. The data can be interpreted with as much confidence
as electromagnetic scattering. After briefly reviewing the present theoretical
and experimental knowledge of neutron densities, we discuss possible parity
violation measurements, their theoretical interpretation, and applications. The
experiments are feasible at existing facilities. We show that theoretical
corrections are either small or well understood, which makes the interpretation
clean. The quantitative relationship to atomic parity nonconservation
observables is examined, and we show that the electron scattering asymmetries
can be directly applied to atomic PNC because the observables have
approximately the same dependence on nuclear shape.


title: The hot neutron star

abstract:
  In this paper the equation of state of hot neutron matter is calculated.
  Involving the Oppenheimer-Volkov-Tolman equation global parameters of a
neutron star at the finite temperature are obtained. The objective of our work
was to study the influence of the temperature on the main parameters of a
neutron star.


title: The Role of the D13 (1520) Resonance in eta Electroproduction

abstract:
  We investigate the electroproduction of eta mesons below a center of momentum
energy of 1.6 GeV, with particular emphasis on the roles of the N*(1535) and
N*(1520) resonances. Using the effective Lagrangian approach, we show that the
transverse helicity amplitude of the N*(1535) can be extracted with good
accuracy from the new eta electroproduction data, under reasonable assumptions
for the strength of the longitudinal helicity amplitude. In addition, although
the differential cross section is found to to have a small sensitivity to the
N*(1520) resonance, it is shown that a recently completed double polarization
experiment is very sensitive to this resonance.


title:
Collective T=0 pairing in N=Z nuclei? Pairing vibrations around 56Ni
  revisited

abstract:
  We present a new analysis of the pairing vibrations around 56Ni, with
emphasis on odd-odd nuclei. This analysis of the experimental excitation
energies is based on the subtraction of average properties that include the
full symmetry energy together with volume, surface and Coulomb terms. The
results clearly indicate a collective behavior of the isovector pairing
vibrations and do not support any appreciable collectivity in the isoscalar
channel.


title:
Non-linear screening corrections of stellar nuclear reaction rates and
  their effects on solar neutrino fluxes

abstract:
  Non-linear electron screening corrections of stellar nuclear fusion rates are
calculated analytically in the framework of the Debye-Huckel model and compared
with the respective ones of Salpeter's weak screening approximation. In typical
solar conditions, the deviation from Salpeter's screening factor is less than
one percent, while for hotter stars such corrections turn out to be of the
order of one percent only over the limits of the Debye-Huckel model. Moreover,
an investigation of the impact of the derived non-linear screening effects on
the solar neutrino fluxes yields insignificant corrections for both the pp and
CNO chain reactions.


title: Kaon Condensation in Dense Matter

abstract:
  The kaon energy in neutron matter is calculated analytically with the
Klein-Gordon equation, by making a Wigner-Seitz cell approximation and
employing a $K^-N$ square well potential. The transition from the low density
Lenz potential, proportional to scattering length, to the high density Hartree
potential is found to begin at fairly low densities. Exact non-relativistic
calculations of the kaon energy in a simple cubic crystal of neutrons are used
to test the Wigner-Seitz and the Ericson-Ericson approximation methods. All the
calculations indicate that by $\sim 4$ times nuclear matter density the Hartree
limit is reached, and as the Hartree potential is less attractive, the density
for kaon condensation appears to higher than previously estimated. Effects of a
hypothetical repulsive core in the $K^-N$ potential are also studied.


title: Pion-Baryon Couplings

abstract:
  We have extended and applied a general QCD parameterization method to the
emission of pions from baryons. We use it to calculate the strength and sign of
the coupling of pions to the octet and decuplet of baryons. Certain relations
between octet and decuplet couplings are pointed out.


title: Temperature dependent BCS equations with continuum coupling

abstract:
  The temperature dependent BCS equations are modified in order to include the
contribution of the continuum single particle states. The influence of the
continuum upon the critical temperature corresponding to the phase transition
from a superfluid to a normal state and upon the behaviour of the excitation
energy and of the entropy is discussed.


title: Model for $J/\psi$ absorption in hadronic matter

abstract:
  The cross sections for $J/\psi$ absorption by $\pi$ and $\rho$ mesons are
studied in a meson-exchange model that includes not only
pseudoscalar-pseudoscalar-vector-meson couplings but also three-vector-meson
and four-point couplings. We find that they are much larger than in a previous
study where only pseudoscalar-pseudoscalar-vector-meson couplings were
considered. Including form factors at interaction vertices, the $J/\psi$
absorption cross sections $\sigma_{\pi \psi}$ and $\sigma_{\rho \psi}$ are
found to have values on the order of 7 mb and 3 mb, respectively. Their thermal
averages in hadronic matter at temperature T=150 MeV are, respectively, about 1
mb and 2 mb.


title:
Single-Particle Spin-Orbit Strengths of the Nucleon and Hyperons by SU6
  Quark-Model

abstract:
  The quark-model hyperon-nucleon interaction suggests an important
antisymmetric spin-orbit component. It is generated from a color analogue of
the Fermi-Breit interaction dominating in the one-gluon exchange process
between quarks. We discuss the strength S_B of the single-particle spin-orbit
potential, following the Scheerbaum's prescription. Using the SU6 quark-model
baryon-baryon interaction which was recently developed by the Kyoto-Niigata
group, we calculate NN, Lambda N and Sigma N G-matrices in symmetric nuclear
matter and apply them to estimate the strength S_B. The ratio of S_B to the
nucleon strength S_N =~ -40 MeV*fm^5 is (S_Lambda)/(S_N) =~ 1/5 and
(S_Sigma)/(S_N) =~ 1/2 in the Born approximation. The G-matrix calculation of
the model FSS modifies S_Lambda to (S_Lambda)/(S_N) =~ 1/12. For S_N and
S_Sigma, the effect of the short-range correlation is comparatively weak
against meson-exchange potentials with a short-range repulsive core. The
significant reduction of the Lambda single-particle potential arises from the
combined effect of the antisymmetric LS force, the flavor-symmetry breaking
originating from the strange to up-down quark-mass difference, as well as the
effect of the short-range correlation. The density dependence of S_B is also
examined.


title: Large Lorentz Scalar and Vector Potentials in Nuclei

abstract:
  In nonrelativistic models of nuclei, the underlying mass scales of low-energy
quantum chromodynamics (QCD) are largely hidden. In contrast, the covariant
formulations used in relativistic phenomenology manifest the QCD scales in
nuclei through large Lorentz scalar and four-vector nucleon self-energies. The
abundant and varied evidence in support of this connection and the consequences
are reviewed.


title:
d+3He Elastic Backward Scattering and the 3He Structure at Sort
  Distances

abstract:
  We study how d+3He beckward elastic scattering is connected with momentum
distribution of the deuteron in 3He. With this aim th relativistic calculations
in the framework of proton exchange is investigated. We also consider possible
reaction mechanisms beyond the proton exchange


title: Solutions of the Wick-Cutkosky model in the Light-Front Dynamics

abstract:
  We study relativistic effects in a system of two scalar particles interacting
via a scalar exchange in the Light Front Dynamcis framework. The results are
compared to those provided by Bethe-Salpeter and non relativistic equations. It
is found in particular that for massive exchange, the relativistic description
is of crucial importance even in the limit of zero binding energy.
  PACS: 11.10, 03.70, 03.65P Keywords: Light-Front Dynamics, Relativistic
equations, Quantum Field Theory


title: Virtual states of light non-Borromean halo nuclei

abstract:
  It is shown that the three-body non-Borromean halo nuclei like ^{12}Be,
^{18}C, ^{20}C have p-wave virtual states with energy of about 1.6 times the
corresponding neutron-core binding energy. We use a renormalizable model that
guarantees the general validity of our results in the context of short range
interactions.


title: Structure of ^{19}C from Coulomb dissociation studies

abstract:
  We investigate the structure of the neutron rich nucleus ^{19}C through
studies of its breakup in the Coulomb field of target nuclei. The breakup
amplitude is calculated within an adiabatic treatment of the projectile
excitation, which allows the use of the realistic wave functions for the
relative motion between the fragments in the ground state of the projectile.
The angular distribution of the center of mass of ^{19}C, longitudinal momentum
distribution of ^{18}C and relative energy spectrum of the fragments (neutron -
^{18}C) following the breakup of ^{19}C on heavy targets at beam energies below
100 MeV/nucleon have been computed using different configurations for the
ground state wave function of ^{19}C. In all the cases, the data seem to favor
a ^{18}C(0$^+)\otimes1s_{1/2}$ configuration for the ground state of ^{19}C,
with the one-neutron separation energy of 0.53 MeV.


title:
Chiral SU(3) Dynamics with Coupled Channels: Inclusion of P-Wave
  Multipoles

abstract:
  We extend our recent non-perturbative chiral SU(3) coupled channel approach
to pion- and photon-induced $\eta$- and $K$-meson production off protons by
including all strong and electromagnetic p-wave multipoles. We identify the
p-wave amplitudes of the next-to-leading order SU(3) chiral meson-baryon
Lagrangian with a coupled channel potential which is iterated to infinite
orders in a separable Lippmann-Schwinger equation. Our approach to $\eta$- and
$K$-photoproduction introduces no additional free parameters. By adjusting a
few finite range parameters and the unknown parameters in the Lagrangian, we
are able to simultaneously describe a very large amount of low-energy data.
These include the total and differential cross sections of the $\pi$-induced
reactions $\pi^- p \to \eta n, K^0 \Lambda, K^0 \Sigma^0, K^+ \Sigma^-$ and
$\pi^+ p \to K^+ \Sigma^+$ as well as those of photoproduction $\gamma p \to
\eta p, K^+\Lambda, K^+ \Sigma^0, K^0 \Sigma^+$. The polarization observables
measured in $\eta$- and $K$-photoproduction are particularly sensitive to
interference terms between the s- and p-wave multipoles. The total cross
section data are remarkably well reproduced in all channels. There remain,
however, some open questions concerning details of angular distributions and
polarization observables.


title:
Chiral $\pi$-exchange NN-potentials: Results for diagrams proportional
  to g_A^4 and g_A^6

abstract:
  We calculate in (two-loop) chiral perturbation theory the local NN-potentials
generated by the three-pion exchange diagrams proportional to g_A^4 and g_A^6.
Surprisingly, we find that the total isoscalar central $3\pi$-exchange
potential vanishes identically. The individually largest $3\pi$-exchange
potentials are of isoscalar spin-spin, isovector central and isoscalar tensor
type. For these potentials simple analytical expressions can be given. The
strength of these dominant $3\pi$-exchange potentials at r=1.0 fm is 4.6 MeV,
2.9 MeV and 1.4 MeV, respectively. Furthermore, we observe that the spin-spin
and tensor potentials due to the diagrams proportional to g_A^6 do not exist in
the infinite nucleon mass limit.


title: Statistical aspects of nuclear coupling to continuum

abstract:
  Various global characteristics of the coupling between the bound and
scattering states are explicitly studied based on realistic Shell Model
Embedded in the Continuum. In particular, such characteristics are related to
those of the scattering ensemble. It is found that in the region of higher
density of states the coupling to continuum is largely consistent with the
statistical model. However, assumption of channel equivalence in the
statistical model is, in general, violated.

categories: nucl-th chao-dyn cond-mat.str-el nlin.CD


title:
Low momentum nucleon-nucleon potential and shell model effective
  interactions

abstract:
  A low momentum nucleon-nucleon (NN) potential V-low-k is derived from meson
exhange potentials by integrating out the model dependent high momentum modes
of V_NN. The smooth and approximately unique V-low-k is used as input for shell
model calculations instead of the usual Brueckner G matrix. Such an approach
eliminates the nuclear mass dependence of the input interaction one finds in
the G matrix approach, allowing the same input interaction to be used in
different nuclear regions. Shell model calculations of 18O, 134Te and 135I
using the same input V-low-k have been performed. For cut-off momentum Lambda
in the vicinity of 2 fm-1, our calculated low-lying spectra for these nuclei
are in good agreement with experiments, and are weakly dependent on Lambda.


title: Ground State Correlations in 16O and 40Ca

abstract:
  We study the ground state properties of doubly closed shell nuclei $^{16}$O
and $^{40}$Ca in the framework of Correlated Basis Function theory using state
dependent correlations, with central and tensor components. The realistic
Argonne $v_{14}$ and $v'_{8}$ two-nucleon potentials and three-nucleon
potentials of the Urbana class have been adopted. By means of the Fermi
Hypernetted Chain integral equations, in conjunction with the Single Operator
Chain approximation, we evaluate the ground state energy, one- and two-body
densities and electromagnetic and spin static responses for both nuclei. In
$^{16}$O we compare our results with the available Monte Carlo and Coupled
Cluster ones and find a satisfying agreement. As in the nuclear matter case
with similar interactions and wave functions, the nuclei result under-bound by
2--3 MeV/A.


title: Dipole and Quadrupole Moments of Mirror Nuclei 8B and 8li

abstract:
  Magnetic dipole and electric quadrupole moments of the mirror nuclei 8Li and
8B are analysed in the framework of the multiparticle shell model by using two
approaches : i) the one-particle spectroscopic factors and ii) the one-particle
fractional parentage coefficients.
  These two approaches are compared both each to other and with a microscopic
multicluster model. The one-particle nucleon states are calculated taking into
account the continuum by the method of the expansion of the Sturm - Liouville
functions. The experimental magnetic and quadrupole moments of 8Li and 8Bare
reproduced well by using fractional parentage coefficients technique. The root
mean-square radii and the radial density distributions are obtained for these
nuclei.


title:
Hyperon Single-Particle Potentials Calculated from SU6 Quark-Model
  Baryon-Baryon Interactions

abstract:
  Using the SU6 quark-model baryon-baryon interaction recently developed by the
Kyoto-Niigata group, we calculate NN, Lambda N and Sigma N G-matrices in
ordinary nuclear matter. This is the first attempt to discuss the Lambda and
Sigma single-particle potentials in nuclear medium, based on the realistic
quark-model potential. The Lambda potential has the depth of more than 40 MeV,
which is more attractive than the value expected from the experimental data of
Lambda-hypernuclei. The Sigma potential turns out to be repulsive, the origin
of which is traced back to the strong Pauli repulsion in the Sigma N (I=3/2)
^3S_1 state.


title:
Lippmann-Schwinger Resonating-Group Formalism for NN and YN Interactions
  in an SU6 Quark Model

abstract:
  We formulate a Lippmann-Schwinger-type resonating-group equation to calculate
invariant amplitudes of the quark-model baryon-baryon interaction. When applied
to our recent SU6 quark model for the nucleon-nucleon and hyperon-nucleon
interactions, this technique yields very accurate phase-shift parameters for
all partial waves up to the energies of several GeV. The technique also has a
merit of a straightforward extension to the G-matrix equation. A new analytic
method is proposed to calculate the quark-exchange Born kernel for the
momentum-dependent two-body interaction. The partial-wave decomposition in the
momentum representation is carried out numerically. The invariant amplitudes
are then used to calculate single-nucleon potentials in normal nuclear matter
for high incident momenta q_1 > 3 (1/fm), in which the so-called t^eff-rho
prescription is found to be a good approximation to the single-particle
potentials directly calculated in the lowest-order Brueckner theory.


title:
A Schematic Model for $\rho$-$a_1$ Mixing at Finite Density and
  In-Medium Effective Lagrangian

abstract:
  Based on schematic two-level models extended to $a_1$-meson degrees of
freedom, we investigate possible mechanisms of chiral restoration in the
vector/axialvector channels in cold nuclear matter. In the first part of this
article we employ the massive Yang-Mills framework to construct an effective
chiral Lagrangian based on low-energy mesonic modes at finite density. The
latter are identified through nuclear collective excitations of `meson'-sobar
type such as $\pi\leftrightarrow [\Delta (1232)N^{-1}]\equiv\hat\pi$,
$\rho\leftrightarrow [N^* (1520)N^{-1}]\equiv\hat\rho$, etc.. In a mean-field
type treatment the in-medium gauge coupling $\hat g$, the (axial-) vector meson
masses and $\hat f_\pi$ are found to decrease with density indicating the
approach towards chiral restoration in the language of in-medium effective
fields. In the second part of our analysis we evaluate the (first) in-medium
Weinberg sum rule which relates vector and axialvector correlators to the pion
decay constant. Using in-medium $\rho$/$a_1$ spectral functions (computed in
the two-level model) also leads to a substantial reduction of the pion decay
constant with increasing density.


title: Dissipation in finite Fermi systems

abstract:
  We present a systematic theory of dissipation in finite Fermi systems like
nuclei and metallic clusters. This theory is based on the application of
semiclassical methods and random matrix theory to linear response of many-body
systems. The theory is developed in the approximation wherein the many-body
system can be treated as a single particle in an effective, time-dependent
mean-field. We find semiclassical expressions for energy dissipation relevant
in one-body dissipation in heavy nuclei. We also show that this energy
dissipation, related to damping of collective excitations, is irreversible. The
irreversibility is proved by our development of a quantum diffusion equation.
It may be noted that the quantum diffusion equation is derived from the von
Neumann equation and makes no assumption about the initial form of the density
operator. It is shown that, in the semiclassical limit, the quantum diffusion
equation reduces to the classical Smoluchowski equation. Further, we show that
the dissipation is a purely quantal phenomenon as it is related to the
geometric phase acquired by a single-particle wavefunction as the system
evolves in a slow-varying mean-field. It is explicitly shown that the
dissipation rate is related to the nature of dynamics and the spectrum of the
classical Liouvillian operator. Finally, we present an expression for the
viscosity tensor encountered in nuclear fission in terms of periodic orbits of
the single particle in an adiabatically deforming nucleus.


title: H-dibaryon

abstract:
  The quark cluster model studies concerning the H-dibaryon are reviewed. The
covered topics are the H-dibaryon itself, the interaction between a nucleon and
an H-dibaryon, and the one between two H-dibaryons. A related study on the
H-dibaryon in nuclear matter is also reviewed and its implication to double
hypernuclei is discussed.


title: Nonextensive statistics in stellar plasma and solar neutrinos

abstract:
  Nonextensive and quantum uncertainty effects (related to the quasiparticles
composing the stellar core) have strong influence on the nuclear rates and, of
course, affect solar neutrino fluxes. Both effects do coexist and are due to
the frequent collisions among the ions. The weakly nonextensive nature of the
solar core is confirmed. The range of predictions for the neutrino fluxes is
enlarged and the solar neutrino problem becomes less dramatic.

categories: nucl-th astro-ph cond-mat.stat-mech hep-ph


title:
Study of Light Lambda- and Lambda Lambda-Hypernuclei with the Stochastic
  Variational Method and Effective Lambda N Potentials

abstract:
  We first determine the Lambda-N S-wave phase shifts so as to reproduce the
experimental Lambda separation energies of A=3, 4 Lambda-hypernuclei, and then
construct three phase-equivalent Lambda-N potentials with different central
repulsion. By the stochastic variational method with correlated Gaussian basis
we perform an extensive calculation of ab initio type for the hypernuclei of up
to A=6. The binding energies and the sizes of the Lambda-hypernuclei are very
insensitive to the type of the phase-equivalent Lambda-N potentials. We use two
different Lambda-Lambda potentials which both reproduce Delta B_{Lambda Lambda}
of 6He_{Lambda Lambda} reasonably well. Any combination of these Lambda-N and
Lambda-Lambda potentials predicts hitherto undiscovered particle-stable bound
states, 4H_{Lambda Lambda}, 5H_{Lambda Lambda} and 5He_{Lambda Lambda}:
Predicted values of B_{Lambda Lambda} are about 0.4, 5.5 and 6.3 MeV,
respectively. The binding energy of 4H_{Lambda Lambda} is so small that its
possibility crucially depends on the strength of the Lambda-Lambda interaction.
The binding energies of both 5He_Lambda and 6He_{Lambda Lambda} are calculated
to be strongly overbound compared to experiment. In relation to this well-known
anomaly we examine the effect of the quark substructure of $N$ and Lambda on
their binding energies. The effect is negligible if the baryon size in which
three quarks are confined is smaller than 0.6 fm, but becomes appreciable,
particularly in 6He_{Lambda Lambda}, if the size is taken to be as large as 0.7
fm. We discuss the extent to which the nucleon subsystem in the hypernuclei
changes by the addition of Lambda particles. The charge symmetry breaking of
the Lambda-N potential is phenomenologically determined and concluded to be
weakly spin-dependent.


title: Hyperon stars in the Brueckner-Bethe-Goldstone theory

abstract:
  In the framework of the Brueckner-Bethe-Goldstone theory, we determine a
fully microscopic equation of state for asymmetric and $\beta$-stable nuclear
matter containing $\sim$ and $\la$ hyperons. We use the Paris and the new
Argonne $Av_{18}$ two-body nucleon interaction, whereas the nucleon-hyperon
interaction is described by the Njimegen soft-core model. We stress the role
played by the three-body nucleon interaction, which produces a strong repulsion
at high densities. This enhances enormously the hyperon population, and
produces a strong softening of the equation of state, which turns out almost
independent on the nucleon-nucleon interaction. We use the new equation of
state in order to calculate the structure of static neutron stars. We obtain a
maximum mass configuration with $M_{\rm max}$ = 1.26 (1.22) when the Paris
($Av_{18}$) nucleon potential is adopted. Central densities are about 10 times
normal nuclear matter density. Stellar rotations, treated within a perturbative
approach, increase the value of the limiting mass by about 12%.


title:
Target-mass corrections and the Bloom-Gilman duality of the nucleon
  structure function

abstract:
  The occurrence of the Bloom-Gilman local duality in the low-order moments of
the nucleon structure function is investigated for values of the squared
four-momentum transfer Q**2 between ~ 0.5 and 10 (GeV/c)**2. At variance with
previous analyses truncated Cornwall-Norton moments, limited to the
nucleon-resonance production regions, are considered. The role played by
target-mass corrections is illustrated, showing that target-mass effects are
necessary (but not sufficient) for producing the observed Bloom-Gilman duality
of the nucleon structure function. The possibility of a local duality between
the unphysical region at large values of the Nachtmann variable and the nucleon
elastic peak contribution is analyzed. It is found that the proton magnetic
form factor extracted assuming local duality is significantly below the
experimental data at low and intermediate values of Q**2.


title: Solving the pairing problem with exact particle number conservation

abstract: This paper has been withdrawn by the authors


title: The electro production of d* dibaryon

abstract:
  $d^*$ dibaryon study is a critical test of hadron interaction models. The
electro production cross sections of $ed\to ed^*$ have been calculated based on
the meson exchange current model and the cross section around 30 degree of 1
GeV electron in the laboratory frame is about 10 nb. The implication of this
result for the $d^*$ dibaryon search has been discussed.


title: Critical Line for H-Superfluidity in Strange Quark Matter?

abstract:
  Based upon the analogy to the electroweak phase diagram, I propose that in
QCD there might be a critical line for a superfluid transition, in the plane of
chemical potential and temperature. The order parameter has the quantum numbers
of the H-dibaryon, but the transition is driven by color superconductivity in
strange quark matter.


title:
Partial Dynamical SU(3) Symmetry and the Nature of the Lowest K=0
  Collective Excitation in Deformed Nuclei

abstract:
  We discuss the implications of partial dynamical SU(3) symmetry (PDS) for the
structure of the lowest K=0^{+} (K=0_2) collective excitation in deformed
nuclei. We consider an interacting boson model Hamiltonian whose ground and
gamma bands have good SU(3) symmetry while the K=0_2 band is mixed. It is shown
that the double-phonon components in the K=0_2 wave function arise from SU(3)
admixtures which, in turn, can be determined from absolute E2 rates connecting
the K=0_2 and ground bands. An explicit expression is derived for these
admixtures in terms of the ratio of K=0_2 and gamma bandhead energies. The
SU(3) PDS predictions are compared with existing data and with broken-SU(3)
calculations for ^{168}Er.


title:
Point symmetries in the Hartree-Fock approach: Densities, shapes and
  currents

abstract:
  Three mutually perpendicular symmetry axes of the second order, inversion,
and time reversal can be used to construct a double point group denoted by
D2h(TD). Properties of this group are analyzed in relation to the symmetry and
symmetry-breaking effects within the mean-field (Hartree-Fock) theories, both
in even and odd fermion systems. We enumerate space symmetries of local
one-body densities, and symmetries of electromagnetic moments, that appear when
some or all of the D2h(TD) elements represent self-consistent mean-field
symmetries.