title:
Effective nucleon-nucleon interactions and nuclear matter equation of
  state

abstract:
  Nuclear matter equations of state based on Skyrme, Myers-Swiatecki and
Tondeur interactions are written as polynomials of the cubic root of density,
with coefficients that are functions of the relative neutron excess $\delta$.
In the extrapolation toward states far away from the standard one, it is shown
that the asymmetry dependence of the critical point ($\rho_c, \delta_c$)
depends on the model used. However, when the equations of state are fitted to
the same standard state, the value of $\delta_c$ is almost the same in Skyrme
and in Myers-Swiatecki interactions, while is much lower in Tondeur
interaction. Furthermore, $\delta_c$ does not depend sensitively on the choice
of the parameter $\gamma$ in Skyrme interaction.


title: Nuclear matter properties and relativistic mean-field theory

abstract:
  Nuclear matter properties are calculated in the relativistic mean field
theory by using a number of different parameter sets. The result shows that the
volume energy $a_1$ and the symmetry energy $J$ are around the acceptable
values 16MeV and 30MeV respectively; the incompressibility $K_0$ is
unacceptably high in the linear model, but assumes reasonable value if
nonlinear terms are included; the density symmetry $L$ is around $100MeV$ for
most parameter sets, and the symmetry incompressibility $K_s$ has positive sign
which is opposite to expectations based on the nonrelativistic model. In almost
all parameter sets there exists a critical point $(\rho_c, \delta_c)$, where
the minimum and the maximum of the equation of state are coincident and the
incompressibility equals zero, falling into ranges
0.014fm$^{-3}<\rho_c<0.039$fm$^{-3}$ and $0.74<\delta_c\le0.95$; for a few
parameter sets there is no critical point and the pure neutron matter is
predicted to be bound. The maximum mass $M_{NS}$ of neutron stars is predicted
in the range 2.45M$_\odot\leq M_{NS}\leq 3.26$M$_\odot$, the corresponding
neutron star radius $R_{NS}$ is in the range 12.2km$\leq R_{NS}\leq 15.1$km.


title: Realistic models of pion-exchange three-nucleon interactions

abstract:
  We present realistic models of pion-exchange three-nucleon interactions
obtained by fitting the energies of all the 17 bound or narrow states of 3 <= A
<= 8 nucleons, calculated with less than 2% error using the Green's function
Monte Carlo method. The models contain two-pion-exchange terms due to pi-N
scattering in S- and P-waves, three-pion-exchange terms due to ring diagrams
with one Delta in the intermediate states, and a phenomenological repulsive
term. The models have five parameters: the four strengths and the short-range
cutoff. The 17 fitted energies are insufficient to determine all of them
uniquely.
  We consider five models; they reproduce the observed energies with an rms
error < 1% when used together with the Argonne v18 two-nucleon interaction. In
one of the models the pi-N S-wave scattering interaction is set to zero; in all
others it has the strength suggested by chiral effective field theory. One
model also assumes that the pi-N P-wave scattering interaction has the strength
suggested by effective field theories, and the cutoff is adjusted to fit the
data. In all other models the cutoff is taken to be the same as in the AV18
interaction. The effect of relativistic boost correction is estimated. Results
obtained with only Argonne v8' and v18 interactions are also reported. In
addition, we present results for 7- and 8-body neutron drops in external
potential wells.


title: Scaling of single photon production in hadronic collisions

abstract:
  Scaling of single photon production in $pp$ and $p\overline{p}$ collisions is
studied. It is empirically observed the available data scales $\sim
\sqrt{s}/p_T^5$ for $x_T=2p_T/\sqrt{s} \leq 0.1$ and $\sim
(\sqrt{s})^{3.3}/p_T^9$ for larger $x_T$. The NLO pQCD predictions for $pp$
collisions at $\sqrt{s}$ of 200 and 5500 GeV, relevant for RHIC and LHC
energies are seen to closely follow this scaling behaviour. Implications for
single photon production in heavy ion collisions are discussed.


title: On radiative muon capture in hydrogen

abstract:
  We analyze photon spectra in the radiative muon capture in hydrogen using
amplitudes derived from chiral Lagrangians. The model can describe the high
energy part of the photon spectra, measured recently at TRIUMF, reasonably
well.


title:
Comment on "Coulomb corrections to e^+e^- production in
  ultra-relativistic nuclear collisions"

abstract:
  The qualitative difference in the use of retarded and Feynman amplitudes as
demonstrated in nucl-th/0101024 had been wrongly considered in this comment.
The concept of the breakdown of crossing symmetry is not effective in the case
considered in the adressed article. The technical aspects of the evaluation of
higher-order corrections which were adressed in the original comment and their
applicability to the total inclusive cross section have been clarified.


title: Statistical evolution of fragment isospin in nuclear multifragmentation

abstract:
  Two instructive effects concerning fragment production at disintegration of
finite nuclei are predicted with the statistical multifragmentation model: (1)
a concentration of neutrons in intermediate mass fragments during the phase
transition, (2) the break of the spatial symmetry of the fragment's isospin
distribution, as well as of the symmetry of the fragment's emission from a
statistical source, induced by the external Coulomb field.


title:
Softening of the nuclear equation-of-state by kinetic non-equilibrium in
  heavy ion collision

abstract:
  Highly compressed nuclear matter created in relativistic heavy collisions is
to large extent governed by local non-equilibrium. As an idealised scenario
colliding nuclear matter configurations are studied with an effective in-medium
interaction based on the microscopic DBHF model. It is found that on top of the
repulsive momentum dependence of the nuclear forces kinetic non-equilibrium
leads to an effective softening of the equation of state as compared to ground
state nuclear matter. The separation of phase space which is the basic feature
of such anisotropic configurations has thereby a similar influence as the
introduction of a virtual new degree of freedom.


title:
Testing Dirac-Brueckner models in collective flow of heavy-ion
  collisions

abstract:
  We investigate differential in-plane and out-of-plane flow observables in
heavy ion reactions at intermediate energies from $0.2\div 2$ AGeV within the
framework of relativistic BUU transport calculations. The mean field is based
on microscopic Dirac-Brueckner-Hartree-Fock (DBHF) calculations. We apply two
different sets of DBHF predictions, those of ter Haar and Malfliet and more
recent ones from the T\"ubingen group, which are similar in general but differ
in details. The latter DBHF calculations exclude spurious contributions from
the negative energy sector to the mean field which results in a slightly softer
equation of state and a less repulsive momentum dependence of the
nucleon-nucleus potential at high densities and high momenta. For the
application to heavy ion collisions in both cases non-equilibrium features of
the phase space are taken into account on the level of the effective
interaction. The systematic comparison to experimental data favours the less
repulsive and softer model. Relative to non-relativistic approaches one obtains
larger values of the effective nucleon mass. This produces a sufficient amount
of repulsion to describe the differential flow data reasonably well.


title:
Event-by-event analysis of ultra-relativistic heavy-ion collisions in
  smoothed particle hydrodynamics

abstract:
  The method of smoothed particle hydrodynamics (SPH) is applied for
ultra-relativistic heavy-ion collisions. The SPH method has several advantages
in studying event-by-event fluctuations, which attract much attention in
looking for quark gluon plasma (QGP) formation, because it gives a rather
simple scheme for solving hydrodynamical equations. Using initial conditions
for Au+Au collisions at RHIC energy produced by NeXus event generator, we solve
the hydrodynamical equation in event-by-event basis and study the fluctuations
of hadronic observables such as dN/dy due to the initial conditions. In
particular, fluctuations of elliptic flow coefficient v2 is investigated for
both the cases, with and without QGP formation. This can be used as an
additional test of QGP formation.


title: Nuclear fragmentation by tunneling

abstract:
  Fragmentation of nuclear system by tunneling is discussed in a molecular
dynamics simulation coupled with imaginary time method. In this way we obtain
informations on the fragmenting systems at low densities and temperatures.
These conditions cannot be reached normally (i.e. above the barrier) in
nucleus-nucleus or nucleon-nucleus collisions. The price to pay is the small
probability of fragmentation by tunneling but we obtain observables which can
be a clear signature of such phenomena.


title:
Electromagnetic Form Factors of the Nucleon in a Relativistic Quark Pair
  Creation Model

abstract:
  We study the effects of the | qqq q\bar{q} > component of the hadronic wave
function on the description of the electromagnetic structure of the nucleon.
Starting with a qqq baryonic wave function which describes the baryonic and
mesonic low energy spectrum, the extra q\bar{q} pair is generated through a
relativistic version of the 3P_0 model. It is shown that this model leads to a
renormalization of the quark mass that allows one to construct a conserved
electromagnetic current. We conclude that these dynamical relativistic
corrections play an important role in reproducing the Q2 dependence of the
electromagnetic form factors at low Q^2.


title: Utility of su(1,1)-Algebra in a Schematic Nuclear su(2)-Model

abstract:
  The su(2)-algebraic model interacting with an environment is investigated
from a viewpoint of treating the dissipative system. By using the
time-dependent variational approach with a coherent state and with the help of
the canonicity condition, the time-evolution of this quantum many-body system
is described in terms of the canonical equations of motion in the classical
mechanics. Then, it is shown that the su(1,1)-algebra plays an essential role
to deal with this model. An exact solution with appropriate initial conditions
is obtained by means of Jacobi's elliptic function. The implication to the
dissipative process is discussed.


title: Core excitation in Coulomb breakup reactions

abstract:
  Within the pure Coulomb breakup mechanism, we investigate the one-neutron
removal reaction of the type A(a,b$\gamma$)X with $^{11}$Be and $^{19}$C
projectiles on a heavy target nucleus $^{208}$Pb at the beam energy of 60
MeV/nucleon. Our intention is to examine the prospective of using these
reactions to study the structure of neutron rich nuclei. Integrated partial
cross sections and momentum distributions for the ground as well as excited
bound states of core nuclei are calculated within the finite range distorted
wave Born approximation as well as within the adiabatic model of the Coulomb
breakup. Our results are compared with those obtained in the studies of the
reactions on a light target where the breakup proceeds via the pure nuclear
mechanism. We find that the transitions to excited states of the core are quite
weak in the Coulomb dominated process as compared to the pure nuclear breakup.


title: Solar reaction rates, non-extensivity and quantum uncertainty

abstract:
  We show that in weakly non-ideal plasmas, like the solar interior, both
non-extensivity and quantum uncertainty (a' la Galitskii and Yakimets) should
be taken into account to derive equilibrium ion distribution functions and to
estimate nuclear reaction rates and solar neutrino fluxes.

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


title:
Extraction of nuclear matter properties from nuclear masses by a model
  of equation of state

abstract:
  The extraction of nuclear matter properties from measured nuclear masses is
investigated in the energy density functional formalism of nuclei. It is shown
that the volume energy $a_1$ and the nuclear incompressibility $K_0$ depend
essentially on $\mu_n N+\bar{\mu}_p Z-2E_N$, whereas the symmetry energy $J$
and the density symmetry coefficient $L$ as well as symmetry incompressibility
$K_s$ depend essentially on $\mu_n-\bar{\mu}_p$, where
$\bar{\mu}_p=\mu_p-\partial E_C/\partial Z$, $\mu_n$ and $\mu_p$ are the
neutron and proton chemical potentials respectively, $E_N$ the nuclear energy,
and $E_C$ the Coulomb energy. The obtained symmetry energy is $J=28.5MeV$,
while other coefficients are uncertain within ranges depending on the model of
nuclear equation of state.


title: Casimir Interaction among Objects Immersed in a Fermionic Environment

abstract:
  Using ensembles of two, three and four spheres immersed in a fermionic
background we evaluate the (integrated) density of states and the Casimir
energy. We thus infer that for sufficiently smooth objects, whose various
geometric characteristic lengths are larger then the Fermi wave length one can
use the simplest semiclassical approximation (the contribution due shortest
periodic orbits only) to evaluate the Casimir energy. We also show that the
Casimir energy for several objects can be represented fairly accurately as a
sum of pairwise Casimir interactions between pairs of objects.

categories: nucl-th astro-ph cond-mat hep-ph nlin.CD physics.atm-clus quant-ph


title: Application of Information Theory in Nuclear Liquid Gas Phase Transition

abstract:
  Information entropy and Zipf's law in the field of information theory have
been used for studying the disassembly of nuclei in the framework of the
isospin dependent lattice gas model and molecular dynamical model. We found
that the information entropy in the event space is maximum at the phase
transition point and the mass of the cluster show exactly inversely to its
rank, i.e. Zipf's law appears. Both novel criteria are useful in searching the
nuclear liquid gas phase transition experimentally and theoretically.

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


title: Thermodynamic consistency for nuclear matter calculations

abstract:
  We investigate the relation between the binding energy and the Fermi energy
and between different expressions for the pressure in cold nuclear matter. For
a self-consistent calculation based on a $\Phi$ derivable $T-$matrix
approximation with off-shell propagators the thermodynamic relations are well
satisfied unlike for a $G-$matrix or a $T-$matrix approach using quasi-particle
propagators in the ladder diagrams.


title: Normalization of neutron-proton differential cross sections

abstract:
  The np differential cross section below 350 MeV neutron laboratory energy is
studied using the energy-dependent Nijmegen partial-wave analysis PWA93. We
analyze in detail three experiments, performed at LAMPF, at TRIUMF, and at the
TSL facility in Uppsala. The issue of normalization of $np$ cross sections is
discussed, where we distinguish between measured and calculated normalizations.
This analysis leads to improved treatments of the LAMPF and TRIUMF data over
PWA93. It is shown that the LAMPF and TRIUMF data at Tlab = 212 MeV are in good
agreement with PWA93, that the LAMPF data at Tlab = 162 MeV is also in good
agreement with PWA93, but that the Uppsala data at 162 MeV is in strong
disagreement with PWA93. The reason for the disagreement is, almost certainly,
a systematic flaw in the slope of the Uppsala data.


title:
Radiative alpha-capture cross sections from realistic nucleon-nucleon
  interactions and variational Monte Carlo wave functions

abstract:
  We report the first calculations of cross sections for the radiative capture
reactions t(alpha,gamma)^7Li and ^3He(alpha,gamma)^7Be below 2 MeV which use
wave functions derived from realistic nucleon-nucleon interactions by the
variational Monte Carlo technique. After examining several small corrections to
the dominant E1 operator, we find energy dependences for the low-energy
S-factors which agree reasonably with experimental measurements. There is no
contradiction with the previous theoretical understanding of these processes,
but the zero-energy derivative of the t(alpha,gamma)^7Li S-factor is smaller
than in most models. While this method can in principle predict cross section
normalizations, the normalizations of our results are mostly too low.


title:
Nuclear Stopping as A Probe to In-medium Nucleon-nucleon Cross Section
  in Intermediate Energy Heavy Ion Collisions

abstract:
  Using an isospin-dependent quantum molecular dynamics, nuclear stopping in
intermediate heavy ion collisions has been studied. The calculation has been
done for colliding systems with different neutron-proton ratios in beam energy
ranging from 15MeV/u to 150MeV/u. It is found that, in the energy region from
above Fermi energy to 150MeV/u, nuclear stopping is very sensitive to the
isospin dependence of in-medium nucleon-nucleon cross section, but insensitive
to symmetry potential. From this investigation, we propose that nuclear
stopping can be used as a new probe to extract the information on the isospin
dependence of in-medium nucleon-nucleon cross section in intermediate energy
heavy ion collisions.


title:
Entrance channel dependence and isospin dependence of preequilibrium
  nucleon emission in intermediate energy heavy ion collisions

abstract:
  Using isospin dependent quantum molecular dynamical model, the studies of the
isospin effect on preequilibrium nucleon emission in heavy ion collisions under
different entrance channel conditions show that the ratio of preequilibrium
neutron number to proton number depends strongly on symmetry potential, beam
energy, and the ratio of neutron to proton of the colliding system, but weakly
on isospin dependent in-medium nucleon-nucleon cross sections, impact
parameter, Pauli potential, and momentum dependent interaction in the energy
region from 45MeV/u up to 150 MeV/u where the dynamics is dominated by
nucleon-nucleon collisions. In addition, the ratio of preequilibrium neutron
number to proton number for a neutron-rich colliding system is larger than the
initial value of the ratio of the colliding system, but the ratio for a
neutron-deficient system is less than the initial value.


title:
Non-diffractive mechanisms in the $\phi$ meson photoproduction on
  nucleons

abstract:
  We examine the non-diffractive mechanisms in the $\phi$ meson photoproduction
from threshold up to a few GeV using an effective Lagrangian in a constituent
quark model. The new data from CLAS at large angles can be consistently
accounted for in terms of {\it s}- and {\it u}-channel processes. Isotopic
effects arising from the reactions $\gamma p\to \phi p$ and $\gamma n\to \phi
n$, are investigated by comparing the cross sections and polarized beam
asymmetries. Our result highlights an experimental means of studying
non-diffractive mechanisms in $\phi$ meson photoproduction.


title: Polarization observables in the reaction $p n \to d \phi$

abstract:
  The reaction $p n \to d \phi$ is studied within a covariant boson exchange
model. The behavior of polarization observables being accessible in forthcoming
experiments near threshold is predicted.


title: Towards thermodynamical consistency of qusiparticle picture

abstract:
  The purpose of the present article is to call attention to some realistic
quasiparticle-based description of the quark/gluon matter and its consistent
implementation in thermodynamics. A simple and transparent representation of
the thermodynamical consistency conditions is given. This representation allows
one to review critically and systemize available phenomenological approaches to
the deconfinement problem with respect to their thermodynamical consistency. A
particular attention is paid to the development of a method for treating the
string screening in the dense matter of unbound color charges. The proposed
method yields an integrable effective pair potential which can be incorporated
into the mean-field picture. The results of its application are in reasonable
agreement with lattice data on the QCD thermodynamics.


title:
Model-independent study of the QCD sum rule for the pi NN coupling
  constant

abstract:
  We reinvestigate the QCD sum rule for the pi NN coupling constant, g,
starting from the vacuum-to-pion matrix element of the correlation function of
the interpolating fields of two nucleons. We study in detail the physical
content of the correlation function without referring to the effective theory.
We consider the invariant correlation functions by splitting the correlation
function into different Dirac structures. We show that the coefficients of the
double-pole terms are proportional to g but that the coefficients of the
single-pole terms are not determined by g. In the chiral limit the single-pole
terms as well as the continuum terms are ill defined in the dispersion
integral. Therefore, the use of naive QCD sum rules obtained from the invariant
correlation functions is not justified. A possible procedure to avoid this
difficulty is discussed.


title:
Propagation of mesons in asymmetric nuclear matter in a density
  dependent coupling model

abstract:
  We study the propagation of the light mesons sigma, omega, rho, and a0(980)
in dense hadronic matter in an extended derivative scalar coupling model.
Within the scheme proposed it is possible to unambiguously define effective
density-dependent couplings at the Lagrangian level. We first apply the model
to study asymmetric nuclear matter with fixed isospin asymmetry, and then we
pay particular attention to hypermatter in beta-equilibrium. The equation of
state and the potential contribution to the symmetry coefficient arising from
the mean field approximation are investigated.


title:
Shrinking $\hbar$ as a recipe for revealing classical-like contributions
  in optical potential cross sections

abstract:
  A simple recipe for revealing classical-like contributions in optical
potential cross sections is proposed. The recipe is based on the fact that the
classical-like properties are not expected to depend on the actual value of
$\hbar$. This allows us to identify the classical-like characteristics of an
optical potential cross section by simply repeating the calculation with
different values of $\hbar$, and observing which properties of the cross
section are invariant. This method is applied to the cross sections of a few
optical potentials used to describe the recent data of light heavy-ion elastic
scattering.


title: Elliptic flow from an on-shell parton cascade

abstract:
  Differential elliptic flow out to p_t ~ 5 GeV/c is calculated using the MPC
elastic parton cascade model for Au+Au at Ecm ~ 130A GeV. The results are
compared to recent STAR/RHIC elliptic flow data. An elliptic flow pattern
comparable to the data seems to require initial parton densities at least twice
higher than predicted by the HIJING model. Elliptic flow is also shown to be
sensitive to the hadronization procedure.


title:
Production of $\omega$ and $\phi$ Mesons in Near-Threshold $\pi N$
  Reactions: Baryon Resonances and Validity of the OZI Rule

abstract:
  Results of a combined analysis are presented for the production of $\omega$
and $\phi$ mesons in $\pi N$ reactions in the near-threshold region using
throughoutly a conventional ''non-strange'' dynamics based on such processes
which are allowed by the non-ideal $\omega-\phi$ mixing. We show that strong
interferences of the $t$ (meson exchange) and $s$ and $u$ (nucleon and nucleon
resonance) channels differ significantly in $\omega$ and $\phi$ production
amplitudes. This leads to a decrease of the relative yields in comparison with
expectations based on one-channel models with standard $\omega - \phi$ mixing.
We find a strong and non-trivial difference between observables in $\omega$ and
$\phi$ production reactions caused by the different role of the nucleon and
nucleon resonance amplitudes. A series of predictions for the experimental
study of this effect is presented.


title: Mesonic cloud contribution to the nucleon and delta masses

abstract:
  Pion-nucleon elastic scattering in the dominant $P_{33}$ channel is examined
in the model in which the interaction is of the form $\pi + N\leftrightarrow N,
\Delta(1232)$. New expressions are found for the elastic pion-nucleon
scattering amplitude which differ from existing formula both in the kinematics
and in the treatment of the renormalization of the nucleon mass and coupling
constant. Fitting the model to the phase shifts in the $P_{33}$ channel does
not uniquely fix the parameters of the model. The cutoff for the pion-nucleon
form factor is found to lie in the range $\beta = 750\pm350$ MeV/c. The masses
of the nucleon and the $\Delta$ which would arise if there were no coupling to
mesons are found to be $m_{_N}^{(0)}= 1200\pm 200$ MeV and $m_\Delta^{(0)} =
1500\pm 200$ MeV. The difference in these bare masses, a quantity which would
be accounted for by a residual gluon interaction, is found to be $\delta
m^{(0)}=350\pm 100$ MeV.


title:
New mechanism for the enhancement of $sd$ dominance in interacting boson
  models

abstract:
  We introduce an exactly solvable model for interacting bosons that extend up
to high spin and interact through a repulsive pairing force. The model exhibits
a phase transition to a state with almost complete $sd$ dominance. The
repulsive pairing interaction that underlies the model has a natural
microscopic origin in the Pauli exclusion principle between contituent
nucleons. As such, repulsive pairing between bosons seems to provide a new
mechanism for the enhancement of $sd$ dominance, giving further support for the
validity of the $sd$ Interacting Boson Model.


title: Asymmetric Nuclear Matter from Extended Brueckner-Hartree-Fock Approach

abstract:
  The properties of isospin-asymmetric nuclear matter have been investigated in
the framework of the extended Brueckner-Hartree-Fock approximation at zero
temperature. Self-consistent calculations using the Argonne $V_{14}$
interaction are reported for several asymmetry parameters $\beta = \frac{N -
Z}{A}$ ranging from symmetric nuclear matter to pure neutron matter. The
binding energy per nucleon fulfills the $\beta^2$ law in the whole asymmetry
range. The symmetry energy is calculated for different densities and discussed
in comparison with other predictions. At the saturation point it is in fairly
good agreement with the empirical value. The present approximation, based on
the Landau definition of quasiparticle energy, is investigated in terms of the
Hugenholtz-Van Hove theorem, which is proved to be fulfilled with a good
accuracy at various asymmetries. The isospin dependence of the single-particle
properties is discussed, including mean field, effective mass, and mean free
path of neutrons and protons. The isospin effects in nuclear physics and
nuclear astrophysics are briefly discussed.


title: Polarization observables in (${\vec \gamma},{\vec N}N$) reactions

abstract:
  The formalism of (${\vec \gamma},{\vec N}N$) reactions is given where the
incident photon is polarized and the outgoing nucleon polarization is detected.
Sixteen structure functions and fifteen polarization observables are found in
the general case, while only eight structure functions and seven polarizations
observables survive in coplanar kinematics. Numerical examples are presented
for the $^{16}$O($\gamma,pn$) and $^{16}$O($\gamma,pp$) reactions. The
transitions to the ground state of $^{14}$C and $^{14}$N are calculated in a
model where realistic short-range and tensor correlations are taken into
account for the $pn$ pair, while short-range and long-range correlations are
included in a consistent way for $pp$ pairs. The effects of the one-body and
two-body components of the nuclear current and the role of correlations in
cross sections and polarizations are studied and discussed.


title: Unitary Transformations in Quantum Field Theory and Bound States

abstract:
  Finding the eigenstates of the total Hamiltonian H or its diagonalization is
the important problem of quantum physics. However, in relativistic quantum
field theory (RQFT) its complete and exact solution is possible for a few
simple models only. Unitary transformations (UT's) considered in this survey do
not diagonalize H, but convert H into a form which enables us to find
approximately some H eigenstates. During the last years there have appeared
many papers devoted to physical applications of such UT's. Our aim is to
present a systematic and self-sufficient exposition of the UT method. The two
general kinds of UT's are pointed out, distinct variations of each kind being
possible. We consider in detail the problem of finding the simplest H
eigenstates for interacting mesons and nucleons using the so-called
``clothing'' UT and Okubo's UT. These UT's allow us to suggest definite
approaches to the problem of two-particle (deuteron-like) bound states in RQFT.
The approaches are shown to yield the same two-nucleon quasipotentials in the
first nonvanishing approximation. We demonstrate how the particle mass
renormalization can be fulfilled in the framework of the ``clothing''
procedure. Besides the UT of the Hamiltonian we discuss the accompanying UT of
the Lorentz boost generators.


title: Nuclear Matter EOS with a Three-body Force

abstract:
  The effect of a microscopic three-body force on the saturation properties of
nuclear matter is studied within the Brueckner-Hartree-Fock approach. The
calculations show a decisive improvement of the saturation density along with
an overall agreement with the empirical saturation point. With the three-body
force the symmetry energy turns more rapidly increasing with density, which
allows for the direct URCA process to occur in $\beta$-stable neutron star
matter. The influence of the three-body force on the nuclear mean field does
not diminish the role of the ground state correlations.


title:
Directed and Elliptic Flow in $^{112}$Sn + $^{112}$Sn Collisions below
  100 MeV/nucleon

abstract:
  The directed and elliptic flow in collisions of $^{112}Sn$ + $^{112}Sn$ at
energies from 35 to 90 MeV/nucleon were studied in an isospin-dependent quantum
molecule dynamics model (IQMD). With increasing incident energy, the directed
flow rises from the negative flow to the positive flow. Its magnitude depends
on the nuclear equation of state (EOS). However, the elliptic flow shows
decrease with increasing incident energy and its magnitude is not very sensible
to EOS. Systematic studies of the impact parameter dependence and cluster mass
dependence were also performed. The study of directed flow at intermediate
energies thus provides a means to extract the information on the nuclear
equation of state.


title:
How a quark-gluon plasma phase modifies the bounds on extra dimensions
  from SN 1987a

abstract:
  The shape of the neutrino pulse from the supernova SN1987a provides one of
the most stringent constraints on the size of large, compact, "gravity-only"
extra dimensions. Previously, calculations have been carried out for a
newly-born proto-neutron star with a temperature of about 50 MeV at nuclear
matter density. It is arguable that, due to the extreme conditions in the
interior of the star, matter might be a quark-gluon plasma, where the relevant
degrees of freedom are quarks and gluons rather than nucleons. We consider an
energy-loss scenario where seconds after rebounce the core of the star consists
of a hot and dense quark-gluon plasma. Adopting a simplified model of the
plasma we derive the necessary energy-loss formulae in the soft-radiation
limit. The emissivity is found to be comparable to the one for nuclear matter
and bounds on the radius of extra dimensions are similar to those found
previously from nuclear matter calculations.


title: The stability of the scalar $\chi^2\phi$ interaction

abstract:
  A scalar field theory with a $\chi^\dag\chi\phi$ interaction is known to be
unstable. Yet it has been used frequently without any sign of instability in
standard text book examples and research articles. In order to reconcile these
seemingly conflicting results, we show that the theory is stable if the Fock
space of all intermediate states is limited to a {\em finite} number of
$\chi{\bar\chi}$ loops associated with field $\chi$ that appears quadradically
in the interaction, and that instability arises only when intermediate states
include these loops to all orders.


title: Continuum QRPA in the coordinate space representation

abstract:
  We formulate a quasi-particle random phase approximation (QRPA) in the
coordinate space representation. This model is a natural extension of the RPA
model of Shlomo and Bertsch to open-shell nuclei in order to take into account
pairing correlations together with the coupling to the continuum. We apply it
to the $^{120}$Sn nucleus and show that low-lying excitation modes are
significantly influenced by the pairing effects although the effects are
marginal in the giant resonance region. The dependence of the pairing effect on
the parity of low-lying collective mode is also discussed.


title: Quark model predictions for $K^*$ photoproduction on the proton

abstract:
  The photoproduction of $K^*$ vector mesons is investigated in a quark model
with an effective Lagrangian. Including both baryon resonance excitations and
{\it t}-channel exchanges, observables for the reactions $\gamma p\to
K^{*0}\Sigma^+$ and $\gamma p\to K^{*+}\Sigma^0$ are predicted, using the
SU(3)-flavor-blind assumption of non-perturbative QCD.


title: Exact Conservation Laws of the Gradient Expanded Kadanoff-Baym Equations

abstract:
  It is shown that the Kadanoff-Baym equations at consistent first-order
gradient approximation reveal exact rather than approximate conservation laws
related to global symmetries of the system. The conserved currents and
energy-momentum tensor coincide with corresponding Noether quantities in the
local approximation. These exact conservations are valid, provided a
Phi-derivable approximation is used to describe the system, and possible memory
effects in the collision term are also consistently evaluated up to first-order
gradients.

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


title:
Collective response of nuclei: Comparison between experiments and
  extended mean-field calculations

abstract:
  The giant monopole, dipole and quadrupole responses in $^{40}$Ca, $^{90}$Zr,
$^{120}$Sn and $^{208}$Pb are investigated using linear response treatment
based on a stochastic one-body transport theory. Effects of the coupling to
low-lying surface modes (coherent mechanism) and the incoherent mechanism due
to nucleon-nucleon collisions are included beyond the usual mean-field
description. We emphasize the importance of both mechanism in the fragmentation
and damping of giant resonance. Calculated spectra are compared with experiment
in terms of percentage of Energy-Weighted Sum-Rules in various energy regions.
We obtained reasonable agreement in all cases. A special attention as been
given to the fragmentation of the Giant Quadrupole Resonance in calcium and
lead. In particular, the equal splitting of the $2^{+}$ in $^{40}$Ca is
correctly reproduced. In addition, the appearance of fine structure in the
response $^{208}$Pb is partly described by the calculations in which the
coherent mechanism play an important role.


title: Effect of form factors in fits to photoproduction data

abstract:
  We compare the effects of several form factor recipes in fits to pseudoscalar
meson photoproduction data. The specific examples of pion and kaon
photoproduction are used to illustrate how different choices can alter the
results of such analyses.


title: Shell Model Description of Isotope Shifts in Calcium

abstract:
  Isotope shifts in the nuclear charge radius of even and odd calcium isotopes
are calculated within the nuclear shell model. The model space includes all
configurations of nucleons in the $2s, 1d_{3/2}, 1f_{7/2}, {\rm and} ~2p_{3/2}$
orbits. The shell model describes well the energies of the intruder states in
Sc and Ca, as well as the energies of the low-lying $2^+$ and $3^-$ states in
the even Ca isotopes. The characteristic features of the isotope shifts, the
parabolic dependence on $A$ and the prominent odd-even staggering, are well
reproduced by the model. These features are related to the partial breakdown of
the $Z = 20$ shell closure caused by promotion, due to the neutron-proton
interaction, of the $ds$ shell protons into the $fp$ shell.


title:
The Kohn Variational Principle for Elastic Proton--Deuteron Scattering
  above Deuteron Breakup Threshold

abstract:
  The Kohn variational principle is formulated for calculating elastic
proton-deuteron scattering amplitudes at energies above the deuteron breakup
threshold. The use of such a principle with an expansion of the wave function
on the (correlated) hyperspherical harmonic basis is discussed.


title: The deuteron: structure and form factors

abstract:
  A brief review of the history of the discovery of the deuteron in provided.
The current status of both experiment and theory for the elastic electron
scattering is then presented.


title: Relativistic Quantum Dynamics of Many-Body Systems

abstract:
  Relativistic quantum dynamics requires a unitary representation of the
Poincare group on the Hilbert space of states. The dynamics of many-body
systems must satisfy cluster separability requirements. In this paper we
formulate an abstract framework of four dimensional Euclidean Green functions
that can be used to construct relativistic quantum dynamics of N-particle
systems consistent with these requirements. This approach should be useful in
bridging the gap between few-body dynamics based on phenomenological mass
operators and on quantum field theory.


title:
Re-Hardening of Hadron Transverse Mass Spectra in Relativistic Heavy-Ion
  Collisions

abstract:
  We analyze the spectra of pions and protons in heavy-ion collisions at
relativistic energies from 2 A GeV to 65+65 A GeV by using a jet-implemented
hadron-string cascade model. In this energy region, hadron transverse mass
spectra first show softening until SPS energies, and re-hardening may emerge at
RHIC energies. Since hadronic matter is expected to show only softening at
higher energy densities, this re-hardening of spectra can be interpreted as a
good signature of the quark-gluon plasma formation.


title:
Isospin Effect on the Process of Multifragmentation and Dissipation at
  Intermediate Energy Heavy Ion Collisions

abstract:
  In the simulation of intermediate energy heavy ion collisions by using the
isospin dependent quantum molecular dynamics, the isospin effect on the process
of multifragmentation and dissipation has been studied. It is found that the
multiplicity of intermediate mass fragments $N_{imf}$ for the neutron-poor
colliding system is always larger than that for the neutron-rich system, while
the quadrupole of single particle momentum distribution $Q_{zz}$ for the
neutron-poor colliding system is smaller than that of the neutron-rich system
for all projectile-target combinations studied at the beam energies from about
50MeV/nucleon to 150MeV/nucleon. Since $Q_{zz}$ depends strongly on isospin
dependence of in-medium nucleon-nucleon cross section and weakly on symmetry
potential at the above beam energies, it may serve as a good probe to extract
the information on the in-medium nucleon-nucleon cross section. The correlation
between the multiplicity $N_{imf}$ of intermediate mass fragments and the total
numer of charged particles $N_c$ has the behavior similar to $Q_{zz}$, which
can be used as a complementary probe to the in-medium nucleon-nucleon cross
section.


title:
On the possibility of observation of $a_0$-$f_0$ mixing in the $pn \to
  da_0$ reaction

abstract:
  It is shown that, if isospin is not conserved in $a^0_0$- and $f_0$-meson
mixing, forward-backward asymmetry arises in the reaction $pn\to da^0_0$. This
effect increases near the reaction threshold. The asymmetry is estimated within
the framework of a model in which the $a^0_0$-$f_0$ mixing is due to the
virtual $\pi^0\leftrightarrow\eta$ transition and the difference in masses of
the charged and neutral kaons in decay channels. The angular asymmetry near the
threshold of the $pn\to da^0_0$ reaction was found to be large, of the order of
$8\div 15$ %.


title: Analytical approximation for the sphere-sphere Coulomb potential

abstract:
  A simple analytical expression, which closely approximates the Coulomb
potential between two uniformly charged spheres, is presented. This expression
can be used in the optical potential semiclassical analyses which require that
the interaction be analytic on and near the real r-axis.


title:
Semiempirical Shell Model Tabulated Masses for Translead Elements with
  Magic Proton Number Z = 126

abstract:
  We present two tables of calculated masses of translead nuclei, for 351
nuclei with N from 94 to 126 and Z from 82 to 100, and for 1969 nuclei with N
from 126 to 184 and Z from 82 to 126. The tables are calculated from a
semiempirical shell-model mass equation based on Z = 126 as a proton magic
number which seems to be highly extrapolatable inside shell regions. Useful
separation and decay energies are given as well. Some properties of the
calculated masses and applications to superheavy elements are indicated in the
introduction.


title:
An attempt to incorporate separate chemical and thermal freeze outs in
  hydrodynamics

abstract:
  From an analysis of various types of data obtained in relativistic nuclear
collisions, the following picture has emerged in thermal and hydrodynamical
descriptions: as the fluid expands and cools, particles first undergo a
chemical freeze out at T_ch.~160-200 MeV then a thermal freeze out at
T_th~100-140 MeV. In this paper we show how to incorporate these separate
freeze outs consistently in a hydrodynamical code via a modified equation of
state (general case) or via a modified Cooper-Frye formula (particular case of
T_ch. close to T_th. or few particle species undergoing early chemical
freeze-out). The modified equation of state causes faster cooling and may have
sizable impact on the predicted values of observables.


title: K_{l3} transition form factors

abstract:
  The rainbow truncation of the quark Dyson-Schwinger equation is combined with
the ladder Bethe-Salpeter equation for the meson bound state amplitudes and the
dressed quark-W vertex in a manifestly covariant calculation of the K_{l3}
transition form factors and decay width in impulse approximation. With model
gluon parameters previously fixed by the chiral condensate, the pion mass and
decay constant, and the kaon mass, our results for the K_{l3} form factors and
the kaon semileptonic decay width are in good agreement with the experimental
data.


title: Nuclear shadowing at low photon energies

abstract:
  We calculate the shadowing effect in nuclear photoabsorption at low photon
energies (1-3 GeV) within a multiple scattering approach. We avoid some of the
high energy approximations that are usually made in simple Glauber theory like
the narrow width and the eikonal approximation. We find that the main
contribution to nuclear shadowing at low energies stems from $\rho^0$ mesons
with masses well below their pole mass. We also show that the possibility of
scattering in non forward directions allows for a new contribution to shadowing
at low energies: the production of neutral pions as intermediate hadronic
states enhances the shadowing effect in the onset region. For light nuclei and
small photon energies they give rise to about 30% of the total shadowing
effect.


title: Correlations in Many-Body Systems with Two-time Green's Functions

abstract:
  The Kadanoff-Baym (KB) equations are solved numerically for infinite nuclear
matter. In particular we calculate correlation energies and correlation times.
Approximating the Green's functions in the KB collision kernel by the free
Green's functions the Levinson equation is obtained. This approximation is
valid for weak interactions and/or low densities. It relates to the extended
quasi-classical approximation for the spectral function. Comparing the
Levinson, Born and KB calculations allows for an estimate of higher order
spectral corrections to the correlations. A decrease in binding energy is
reported due to spectral correlations and off-shell parts in the reduced
density matrix.


title:
Validity of the one-body current for the calculation of form factors in
  the point form of relativistic quantum mechanics

abstract:
  Form factors are calculated in the point form of relativistic quantum
mechanics for the lowest energy states of a system made of two scalar particles
interacting via the exchange of a massless boson. They are compared to the
exact results obtained by using solutions of the Bethe-Salpeter equation which
are well known in this case (Wick-Cutkosky model). Deficiencies of the
point-form approach together with the single-particle current are emphasised.
They point to the contribution of two-body currents which are required in any
case to fulfil current conservation.


title: Improved lower bounds for the ground-state energy of many-body systems

abstract:
  New lower bounds for the binding energy of a quantum-mechanical system of
interacting particles are presented. The new bounds are expressed in terms of
two-particle quantities and improve the conventional bounds of the Hall-Post
type. They are constructed by considering not only the energy in the
two-particle system, but also the structure of the pair wave function. We apply
the formal results to various numerical examples, and show that in some cases
dramatic improvement over the existing bounds is reached.


title:
Systematic calculation of s-wave pion and kaon self-energies in
  asymmetric nuclear matter

abstract:
  We calculate the pion self-energies in asymmetric nuclear matter in the
two-loop approximation of chiral perturbation theory. We find three types of
corrections beyond the well-known linear density approximation. The resulting
s-wave potential (or equivalent mass-shift) of a $\pi^-$ in the center of a
heavy nucleus like Pb turns out to be $U_{\pi^-}=\Delta m_{\pi^-} \simeq 14$
MeV, about half of what is needed to form the deeply bound and narrow pionic
atom-states recently observed at GSI. The potential for a $\pi^+$ under the
same conditions is $U_{\pi^+}=\Delta m_{\pi^+} \simeq -1$ MeV. In the same way
we calculate the mass-shifts of $K^+$-mesons in symmetric nuclear matter and
neutron matter and find an increase of the $K^+$-mass by 9% and 5%,
respectively. As a further application we give an analytical result for the
third order term in the scattering length expansion of the in-medium
self-energy of an interacting light-boson/heavy-fermion system.


title: Pairing Interaction and Self-Consistent Densities in Neutron-Rich Nuclei

abstract:
  Particle and pairing densities in spherical even-even neutron-rich nuclei are
studied within the Skyrme-Hartree-Fock-Bogoliubov approach with the
density-dependent pairing interaction. The influence of the density dependence
of the pairing interaction on asymptotic properties of nucleonic distributions
are analyzed. It is demonstrated that the size of the neutron halo dramatically
depends on the behavior of the pairing interaction at low density.


title:
Tensor Analyzing Power and Current Conservation in the d+p->3He+g
  reaction

abstract:
  The tensor analyzing power in p+ \vec{d} radiative capture is investigated in
a covariant and gauge invariant approach.The results of the present calculation
are compared with those of other theoretical approaches and with experiment.
Predictions for Ayy at Ed = (150-350) MeV are given. At forward and backward
angles T20, T22 and Ayy are sensitive to the effects of current conservation.
The interplay between effects coming from the nuclear and current structures is
discussed.


title:
Transition quadrupole moments in gamma-soft nuclei and the triaxial
  projected shell model

abstract:
  Transition probabilities of the ground-state bands in $\gamma$-soft nuclei
are studied for the first time using the triaxial projected shell model
approach. It is observed that the angular-momentum dependence of the transition
quadrupole moment $Q_t$ is related to the triaxial deformation of the nuclear
mean-field potential. The introduction of the $\gamma$-degree of freedom in the
shell model basis is shown to have a little influence on the {\it constant}
behavior of the low-spin $Q_t$ in a well-deformed nucleus. However, the {\it
increasing} collectivity with spin for the low-spin states in a $\gamma$-soft
nucleus can only be explained by considering the triaxial mean-field
deformation.


title:
Shape coexistence and tilted-axis rotation in neutron-rich hafnium
  isotopes

abstract:
  We have performed tilted-axis-cranked Hartree-Fock-Bogoliubov calculations
for a neutron-rich hafnium isotope ($^{182}$Hf) whose proton and neutron
numbers are both in the upper shell region. We study whether the shell effects
play a role in producing high-$K$ isomers or highly gamma-deformed states at
high spin. In particular, the possibility of shape coexistence and the effect
of wobbling motion are discussed.


title: Quantum Monte Carlo Calculations of Light Nuclei

abstract:
  Accurate quantum Monte Carlo calculations of ground and low-lying excited
states of light p-shell nuclei are now possible for realistic nuclear
Hamiltonians that fit nucleon-nucleon scattering data. At present, results for
more than 30 different (J^pi;T) states, plus isobaric analogs, in A \leq 8
nuclei have been obtained with an excellent reproduction of the experimental
energy spectrum. These microscopic calculations show that nuclear structure,
including both single-particle and clustering aspects, can be explained
starting from elementary two- and three-nucleon interactions. Various density
and momentum distributions, electromagnetic form factors, and spectroscopic
factors have also been computed, as well as electroweak capture reactions of
astrophysical interest.


title:
Compton scattering on the nucleon at intermediate energies and
  polarizabilities in a microscopic model

abstract:
  A microscopic calculation of Compton scattering on the nucleon is presented
which encompasses the lowest energies -- yielding nucleon polarizabilities --
and extends to energies of the order of 600 MeV. We have used the covariant
"Dressed K-Matrix Model" obeying the symmetry properties which are appropriate
in the different energy regimes. In particular, crossing symmetry, gauge
invariance and unitarity are satisfied. The extent of violation of analyticity
(causality) is used as an expansion parameter.


title: Structure of unstable light nuclei

abstract:
  The structure of light nuclei out to the drip lines and beyond up to Z = 8 is
interpreted in terms of the shell model. Special emphasis is given to the
underlying supermultiplet symmetry of the p-shell nuclei which form cores for
neutrons and protons added in sd-shell orbits. Detailed results are given on
the wave functions, widths, and Coulomb energy shifts for a wide range of
non-normal parity states in the p-shell.


title:
Quark mean field model with density dependent couplings for finite
  nuclei

abstract:
  The quark mean field model, which describes the nucleon using the constituent
quark model, is applied to investigate the properties of finite nuclei. The
couplings of the scalar and vector mesons with quarks are made density
dependent through direct coupling to the scalar field so as to reproduce the
relativistic Brueckner-Hartree-Fock results of nuclear matter. The present
model provides satisfactory results on the properties of spherical nuclei, and
predicts an increasing size of the nucleon as well as a reduction of the
nucleon mass in the nuclear environment


title:
Cluster Emission and Phase Transition Behavior in the Nuclear
  Disassembly

abstract:
  The features of the emissions of light particles ($LP$), charged particles
($CP$), intermediate mass fragments ($IMF$) and the largest fragment ($MAX$)
are investigated for $^{129}Xe$ as functions of temperature and "freeze-out"
density in the frameworks of isospin dependent lattice gas model and classical
molecular dynamics model. Definite turning points for the slopes of average
multiplicity of $LP$, CP and $IMF$, and of the mean mass of the largest
fragment ($A_{max}$) are shown around a liquid gas phase transition temperature
and while the largest variances of the distributions of $LP$, $CP$, $IMF$, and
$MAX$ appear there. It indicates that the cluster emission rate can be taken as
a probe of nuclear liquid gas phase transition and while the largest
fluctuation is simultaneously accompanied at the point of the phase transition
within lattice gas model and molecular dynamics model as the traditional
thermodynamical theory requires when a phase transition occurs.


title: NN potentials from inverse scattering in the J-matrix approach

abstract:
  An approximate inverse scattering method [7,8] has been used to construct
separable potentials with the Laguerre form factors. As an application, we
invert the phase shifts of proton-proton in the $^1S_0$ and $^3P_2-^3F_2$
channels and neutron-proton in the $^3S_1-^3D_1$ channel elastic scattering. In
the latter case the deuteron wave function of a realistic $np$ potential was
used as input.


title: Quantum Vacuum in Hot Nuclear Matter - A Nonperturbative Treatment

abstract:
  We derive the equation of state for hot nuclear matter using Walecka model in
a nonperturbative formalism. We include here the vacuum polarisation effects
arising from the nucleon and scalar mesons through a realignment of the vacuum.
A ground state structure with baryon-antibaryon condensates yields the results
obtained through the relativistic Hartree approximation (RHA) of summing
baryonic tadpole diagrams. Generalization of such a state to include the
quantum effects for the scalar meson fields through the $\sigma$-meson
condensates amounts to summing over a class of multiloop diagrams. The
techniques of thermofield dynamics (TFD) method are used for the finite
temperature and finite density calculations. The in-medium nucleon and sigma
meson masses are also calculated in a self consistent manner. We examine the
liquid-gas phase transition at low temperatures ($\approx$ 20 MeV), as well as
apply the formalism to high temperatures to examine for a possible chiral
symmetry restoration phase transition.


title: Quasiparticle Random Phase Approximation with an optimal Ground State

abstract:
  A new Quasiparticle Random Phase Approximation approach is presented. The
corresponding ground state is variationally determined and exhibits a minimum
energy. New solutions for the ground state, some with spontaneously broken
symmetry, of a solvable Hamiltonian are found. A non-iterative procedure to
solve the non-linear QRPA equations is used and thus all possible solutions are
found. These are compared with the exact results as well as with the solutions
provided by other approaches.


title:
Nuclear fission: The "onset of dissipation" from a microscopic point of
  view

abstract:
  Semi-analytical expressions are suggested for the temperature dependence of
those combinations of transport coefficients which govern the fission process.
This is based on experience with numerical calculations within the linear
response approach and the locally harmonic approximation. A reduced version of
the latter is seen to comply with Kramers' simplified picture of fission. It is
argued that for variable inertia his formula has to be generalized, as already
required by the need that for overdamped motion the inertia must not appear at
all. This situation may already occur above T=2 MeV, where the rate is
determined by the Smoluchowski equation. Consequently, comparison with
experimental results do not give information on the effective damping rate, as
often claimed, but on a special combination of local stiffnesses and the
friction coefficient calculated at the barrier.


title:
Emission of single photons, hadrons, and dileptons in $Pb+Pb$ collisions
  at CERN SPS and quark hadron phase transition

abstract:
  The production of single photons in $Pb+Pb$ collisions at the CERN SPS as
measured by the WA98 experiment is analysed. A quark gluon plasma is assumed to
be formed initially, which expands, cools, hadronizes, and undergoes
freeze-out. A rich hadronic equation of state is used and the transverse
expansion of the interacting system is taken into account. The recent estimates
of photon production in quark-matter (at two loop level) along with the
dominant reactions in the hadronic matter leading to photons are used. About
half of the radiated photons are seen to have a thermal origin. The same
treatment and the initial conditions provide a very good description to
hadronic spectra measured by several groups and the intermediate mass dileptons
measured by the NA50 experiment, lending a strong support to the conclusion
that quark gluon plasma has been formed in these collisions.


title:
Exactly solvable three-body Calogero-type model with translucent
  two-body barriers

abstract:
  A new exactly solvable alternative to the Calogero three-particle model is
proposed. Sharing its confining long-range part, it contains the mere
zero-range two-particle barriers. Their penetrability gives rise to a
tunneling, tunable via their three independent strengths. Their variability can
control the removal of the degeneracy of the energy levels in an innovative,
non-perturbative manner.


title: Self-consistent description of nuclear compressional modes

abstract:
  Isoscalar monopole and dipole compressional modes are computed for a variety
of closed-shell nuclei in a relativistic random-phase approximation to three
different parametrizations of the Walecka model with scalar self-interactions.
Particular emphasis is placed on the role of self-consistency which by itself,
and with little else, guarantees the decoupling of the spurious
isoscalar-dipole strength from the physical response and the conservation of
the vector current. A powerful new relation is introduced to quantify the
violation of the vector current in terms of various ground-state form-factors.
For the isoscalar-dipole mode two distinct regions are clearly identified: (i)
a high-energy component that is sensitive to the size of the nucleus and scales
with the compressibility of the model and (ii) a low-energy component that is
insensitivity to the nuclear compressibility. A fairly good description of both
compressional modes is obtained by using a ``soft'' parametrization having a
compression modulus of K=224 MeV.


title: Shell-Model Description of Lambda Hypernuclei

abstract:
  Empirical data on the spectra of light hypernuclei, especially the data from
recent gamma-ray experiments, is used to constrain the parameters which govern
the p(nucleon)s(Lambda) and p(nucleon)p(Lambda) two-body matrix elements that
enter into shell-model calculations.


title: $\gamma$-Radiation of Excited Nuclear Discrete Levels in Peripheral

abstract:
  A new process of a nuclear excitation to discrete states in peripheral heavy
ion collisions is studied. High energy photons are emitted by the exited nuclei
with energies up to a few tens GeV at angles of a few hundred microradians with
respect to the beam direction. We show that a two stage process where an
electron - positron pair is produced by virtual photons emitted by nuclei and
the n the electron or positron excites the nucleus, has large cross section. It
is equal to about 5 b f or CaCa collisions. On one hand it produces a
significant $\gamma$-rays background in the nuclear f ragmentation region but
on the other hand it could be used to monitoring the nuclear beam intensity at
LHC. These secondary nuclear photons could be a good signal for triggering
peripheral nuclear collisions.


title: Quenching of resonance production in heavy-ion collisions at 1-2 A GeV

abstract:
  We study the pion production in heavy-ion collisions at SIS energies within
the coupled resonance BUU model. The standard calculation overpredicts the pion
multiplicity in the central Au+Au collision at 1 A GeV by about a factor of 2,
which is interpreted as a signature for the quenching of the resonance
production/absorption in nucleon-nucleon collisions at high nuclear density.
Results of the calculations taking into account a specific form of quenching
are presented for pion spectra from light and heavy systems as well as for the
pion in-plane and out-of-plane flow.


title: Elastic electron-deuteron scattering in chiral effective field theory

abstract:
  We calculate elastic electron-deuteron scattering in a chiral effective field
theory approach for few-nucleon systems based on a modified Weinberg power
counting. We construct the current operators and the deuteron wave function at
next-to-leading (NLO) and next-to-next-to-leading (NNLO) order simultaneously
within a projection formalism. The leading order comprises the impulse
approximation of photons coupling to point-like nucleons with an anomalous
magnetic moment. At NLO, we include renormalizations of the single nucleon
operators. To this order, no unknown parameters enter. At NNLO, one
four-nucleon-photon operator appears. Its strength can be determined from the
deuteron magnetic moment. We obtain not only a satisfactory description of the
deuteron structure functions and form factors measured in electron-deuteron
scattering but also find a good convergence for these observables.


title: A correlated model for lambda-hypernuclei

abstract:
  We study the properties of hypernuclei containing one lambda hyperon in the
framework of the correlated basis function theory with Jastrow correlations.
Fermi hypernetted chain integral equations are derived and used to evaluate
energies and one-body densities of lambda hypernuclei having a doubly closed
shell nucleonic core in the jj coupling scheme, from Carbon to Lead. We also
study hypernuclei having the least bound neutron substituted by the lambda
particle. The semi-realistic Afnan and Tang nucleon-nucleon potential and
Bodmer and Usmani lambda-nucleon potential are adopted. The effect of many-body
forces are considered by means either of a three body lambda-nucleon-nucleon
potential of the Argonne type or of a density dependent modification of the
lambda-nucleon interaction, fitted to reproduce the lambda binding energy in
nuclear matter. While Jastrow correlations underestimate the attractive
contribution of the three body $\la$ interaction, the density dependent
potential provides a good description of the lambda binding energies over all
the nuclear masses range, in spite of the relative simplicity of the model.


title:
Erratum: Eur. Phy. J. C 12 (2000) 109 (A Second Look at Single Photon
  Production in $S+Au$ Collisions at 200 A$\cdot$GeV and Implications for Quark
  Hadron Phase Transition)

abstract:
  It has been shown recently that the values of $J_T$ and $J_L$ which appear in
Eqs.(2) and (5) of the above paper and which are taken from the work of
Aurenche et al are too large by a factor of 4. Correcting for this changes the
Fig.~2. More-over, now the emissions from the quark matter dominate only for
$p_T <$ 1 GeV/$c$. The basic result of the paper, that the upper limit of the
single-photon production in the WA80 experiment is consistent with the rates
for photon production at two-loop level remains valid.


title:
Erratum: Eur. Phy. J. C 10 (1999) 487 (Photon production in relativistic
  heavy-ion collisions using rates with two-loop calculations from quark
  matter)

abstract:
  It has been shown recently shown that the values of $J_T$ and $J_L$ which
appear in Eq.(2) and (5) of the above paper and which are taken from the work
of Aurenche et al are too large by a factor of 4. Correcting for this changes
the Fig.~1--4. The basic result of the paper, that the emissions from the quark
matter can outshine those from the hadronic matter when the photon rates upto
two-loop level are used, remains valid though the range of $p_T$ over which it
happens is reduced to $p_T <$ 0.5, 1, and 2 GeV/$c$ respecitively at SPS, RHIC,
and LHC energies.


title: Three-nucleon portrait with pion

abstract:
  We report on recent results obtained by the above collaboration on the
collision processes involving three nucleons, where we pay particular attention
on the dynamical role of the pion. After discussing the case at intermediate
energies, where real pions can be produced and detected, we have considered the
case at lower energies, where the pions being exchanged are virtual. The study
has revealed the presence of some new pion-exchange mechanisms, which leads to
a new three-nucleon force of tensor structure. Recently, the effect of this
tensor three-nucleon force to the spin observables for neutron-deuteron
scattering at low energy has been analyzed, and will be briefly reviewed.


title: Non-local kinetic simulation of heavy ion collisions

abstract:
  The numerical solutions of nonlocal and local Boltzmann kinetic equations for
the simulation of peripheral and central heavy ion reactions are compared. The
experimental finding of enhancement of mid-rapidity matter shows the necessity
to include nonlocal corrections. While the in-medium cross section changes the
number of collisions and not the transferred energy, the nonlocal scenario
changes the energy transferred during collisions. The renormalisation of
quasiparticle energies by using the Pauli-rejected collisions leads to a
further enhancement of mid-rapidity matter distribution and is accompanied by a
dynamical softening of the equation of state.
  The simulation results are parameterised in terms of time dependent
thermodynamical variables in the Fermi liquid sense. This allows one to discuss
dynamical trajectories in phase space. A combination of thermodynamical
observables is constructed which locates instabilities and points of possible
phase transition under iso-nothing conditions. Two different mechanisms of
instability, a short time surface-dominated instability and later a
spinodal-dominated volume instability is found. The latter one occurs only if
the incident energies do not exceed significantly the Fermi energy and might be
attributed to spinodal decomposition.


title:
The effect of gluon depletion on J/psi suppression in pA and AA
  collisions

abstract:
  The enhanced suppression of $J/\psi$ production at large $x_F$ in $pA$
collisions is studied in the framework of gluon depletion at large $x_1$. The
nonperturbative process that modifies the gluon distribution as the gluons
propagate in nuclear matter is described by an evolution equation with a kernal
to be determined by phenomenology. With nuclear shadowing and anti-shadowing
taken into account, the effect on the gluon distribution is shown to be a
depletion in excess of 40% at $x_1 \approx 0.8$ for $A > 100$. There is a small
amount of enhancement of the gluon distribution at small $x_1$, but it does not
lead to any contradiction with the existing data on $J/\psi$ suppression in the
central region. Extentions to $\psi^{\prime}$ suppression and $AB$ collisions
are also investigated in the framework of gluon redistribution.


title: rho -> pi pi decay in nuclear medium

abstract:
  We calculate the medium modifications of the rho pi pi vertex in a
relativistic hadronic framework, incorporating nucleons and Delta(1232)
isobars. We find a substantial increase of the rho pi pi coupling, dominated by
processes where the Delta is excited. The coupling depends significantly on the
virtuality of the rho, which is related to analytic properties of the vertex
function. We analyze the general case of a non-zero three-momentum of the rho
with respect to the nuclear medium, and evaluate the resulting widths and
spectral strength in the transverse and longitudinal channels for the rho -> pi
pi decay. These widths are used to obtain the dilepton yields from rho decays
in relativistic heavy-ion collisions.


title:
Coulomb and nuclear breakup effects in the single neutron removal
  reaction 197Au(17C,16C gamma)X

abstract:
  We analyze the recently obtained new data on the partial cross sections and
parallel momentum distributions for transitions to ground as well as excited
states of the 16C core, in the one-neutron removal reaction 197Au(17C,16C
gamma)X at the beam energy of 61 MeV/nucleon. The Coulomb and nuclear breakup
components of the one-neutron removal cross sections have been calculated
within a finite range distorted wave Born approximation theory and an eikonal
model, respectively. The nuclear contributions dominate the partial cross
sections for the core excited states. By adding the nuclear and Coulomb cross
sections together, a reasonable agreement is obtained with the data for these
states. The shapes of the experimental parallel momentum distributions of the
core states are described well by the theory.


title:
Scaling of hadron masses and widths in thermal models for
  ultra-relativistic heavy-ion collisions

abstract:
  By means of a simple rescaling, modifications of hadron masses and widths are
incorporated into the thermal analysis of particle ratios in ultra-relativistic
heavy-ion collisions. We find that moderate, up to 20%, changes of hadron
masses do not spoil the quality of the fits, which remain as good as those
obtained without modifications. The fits with the modified masses yield,
however, modified values of the optimal temperature and baryon chemical
potential. In particular, with decreasing masses of all hadrons (except for
pseudo-Goldstone bosons) the fitted values of the temperature and the baryon
chemical potential are lowered, with the change approximately proportional to
the scaling of masses. In addition, we find that the broadening of the hadron
widths by less than a factor of two practically does not affect the fits.


title:
The three-dimensional Ising model: A paradigm of liquid-vapor
  coexistence in nuclear multifragmentation

abstract:
  Clusters in the three-dimensional Ising model rigorously obey reducibility
and thermal scaling up to the critical temperature. The barriers extracted from
Arrhenius plots depend on the cluster size as $B \propto A^{\sigma}$ where
$\sigma$ is a critical exponent relating the cluster size to the cluster
surface. All the Arrhenius plots collapse into a single Fisher-like scaling
function indicating liquid-vapor-like phase coexistence and the univariant
equilibrium between percolating clusters and finite clusters. The compelling
similarity with nuclear multifragmentation is discussed.


title:
Optimization of finite-range effective interaction for in-medium cross
  sections

abstract:
  In order to incorporate the finite range effect into effective interactions,
a modification of the Skyrme force by introducing a cut-off factor for high
momentum transfers is proposed. The parameters of the cut-off factor are
determined by fitting the microscopic in-medium cross-sections of Li and
Machleidt over a wide range of energy and nuclear density. Results for the SkM*
and SLy4 forces are presented.


title:
Coulomb Distortion Effects for Electron or Positron Induced $(e,e')$
  Reactions in the Quasielastic Region

abstract:
  In response to recent experimental studies we investigate Coulomb distortion
effects on $(e,e')$ reactions from medium and heavy nuclei for the case of
electrons and positrons. We extend our previously reported full DWBA treatment
of Coulomb distortions to the case of positrons for the $^{208}Pb(e,e')$
reaction in the quasielastic region for a particular nuclear model. In
addition, we use previously reported successful approaches to treating Coulomb
corrections in an approximate way to calculate the Coulomb distortion effects
for $(e,e')$ reactions for both electrons and positrons for the case of a
simple nuclear model for quasielastic knock-out of nucleons. With these results
in hand we develop a simple {\em ad-hoc} approximation for use in analyzing
experiments, and discuss methods of extracting the ``longitudinal structure
function" which enters into evaluation of the Coulomb sum rule. These
techniques are generally valid for lepton induced reactions on nuclei with
momentum transfers greater than approximately 300 $MeV/c$.


title:
The coupling constants g_{\rho\pi\gamma} and g_{\omega\pi\gamma} as
  derived from QCD sum rules}

abstract:
  We employ QCD sum rules to calculate the coupling constants
g$_{\rho\pi\gamma}$ and g$_{\omega\pi\gamma}$ by studying the three point
${\rho\pi\gamma}$- and ${\omega\pi\gamma}$-correlation functions. Our results
for the decay widths $\Gamma(\rho^0\to \pi^0\gamma)$ and $\Gamma(\omega\to
\pi^0\gamma)$ calculated using the obtained coupling constants are in good
agreement with the experimental values of these decay widths.


title:
Anatomy of nuclear shape transition in the relativistic mean field
  theory

abstract:
  A detailed microscopic study of the temperature dependence of the shapes of
some rare-earth nuclei is made in the relativistic mean field theory. Analyses
of the thermal evolution of the single-particle orbitals and their occupancies
leading to the collapse of the deformation are presented. The role of the
non-linear $\sigma-$field on the shape transition in different nuclei is also
investigated; in its absence the shape transition is found to be sharper.


title: Threshold suppression of Lambda spin-orbit splitting

abstract:
  New experimental data on medium to heavy single Lambda hypernuclei revealed a
much larger spin-orbit splitting than observed in older measurements of light
hypernuclei. Taking into account particle threshold effects and the
density-dependence of in-medium coupling constants the apparent suppression of
spin-orbit strength in light hypernuclei as well as the spin-orbit structure
observed in medium to heavy nuclei are explained in a unified manner within the
density dependent relativistic hadron field theory. It is concluded that the
most valuable information on the Lambda spin-orbit dynamics in finite nuclei
has to be extracted from medium to heavy mass nuclei.


title:
The nuclear equation of state probed by $K^+$ production in heavy ion
  collisions

abstract:
  The dependence of $K^+$ production on the nuclear equation of state is
investigated in heavy ion collisions. An increase of the excitation function of
$K^+$ multiplicities obtained in heavy ($Au+Au$) over light ($C+C$) systems
when going far below threshold which has been observed by the KaoS
Collaboration strongly favours a soft equation of state. This observation holds
despite of the influence of an in-medium kaon potential predicted by effective
chiral models which is necessary to reproduce the experimental $K^+$ yields.
Phase space effects are discussed with respect to the $K^+$ excitation
function.


title:
Hartree-Fock-Bogoliubov calculation of charge radii of Sn, Ba, Yb, and
  Pb isotopes

abstract:
  Charge radii of Sn, Ba, Yb, and Pb isotopes are calculated within
Hartree-Fock-Bogoliubov theory with a Skyrme force and a density-dependent
delta-force pairing. We investigate mean field effects of the pairing upon
odd-even staggering of isotope shifts. HFB equations are solved in the
canonical basis. Odd nuclei are treated in the blocking approximation.


title: HFB theory for nuclei near the drip-lines: continuum coupling

abstract:
  We have developed a new HFB code that specifically addresses nuclear
structure physics near the driplines. The HFB equations are solved on a
two-dimensional lattice for axially symmetric even-even nuclei using B-Spline
techniques. The quasiparticle energy spectrum is obtained by direct
diagonalization of the HFB lattice Hamiltonian with LAPACK. The energy spectrum
extends high into the continuum, up to several thousand MeV. Calculations with
Skyrme forces and (density-dependent) delta pairing interactions are now
underway.


title: Charged-current neutrino-208Pb reactions

abstract:
  We present theoretical results on the non flux-averaged
$^{208}Pb(\nu_{e},e^-)^{208}Bi$ and $^{208}Pb(\nu_{\mu},\mu^-)^{208}Bi$
reaction cross sections, obtained within the charge-exchange
Random-Phase-Approximation. A detailed knowledge of these cross sections is
important in different contexts. In particular, it is necessary to assess the
possibility of using lead as a detector in future experiments on supernova
neutrinos, such as OMNIS and LAND, and eventually detect neutrino oscillation
signals by exploiting the spectroscopic properties of $^{208}Bi$. We discuss
the present status on the theoretical predictions of the reaction cross
sections.


title:
Solutions of Faddeev-Yakubovsky equations in configuration space for the
  4N scattering states

abstract:
  The Faddeev-Yakubovsky equations in configuration space have been solved for
the four nucleon system with special interest in their scattering states. We
present results concerning the structure of the first $^4$He, scattering states
in different (T,S) channels including the first inelatic threshold
N+3N$\to$NN+NN and the n-t cross section using realistic potentials.


title: The Continuum Spectrum of the 4N System. Results and Challenges

abstract:
  The recent calculation of the four nucleon continuum spectrum are reviewed.
Faddeev-Yakubovsky equations in configuration space have been solved for the
four nucleon system with special interest in their scattering states. We
present results concerning the structure of the first $^4$He, scattering states
in different (T,S) channels including the first inelatic threshold
N+3N$\to$NN+NN and the n-t cross section using realistic potentials.


title: Pions in isospin asymmetric nuclei

abstract:
  Using a pair of the lightest mirror nuclei, $^3$He and $^3$H, we study the
effect of the medium modification of pion fields on the flavor non-singlet
structure function. The change of the pion fields leads to an enhancement of
the flavor asymmetry of the antiquark distributions in a nucleus.


title: Selected topics on Low Energy Antiproton Physics

abstract:
  Some of the last results on low energy antiproton physics are reviewed. First
Faddeev calculations for \={n}d scattering length are presented.


title:
Compton Scattering off Relativistic Bound States: Two-Photon Vertices,
  Ward-Takahashi Identities, Gauge Invariance and Low-Energy Limit

abstract:
  In a general framework that has been labeled the ``gauging of equations
method'', we study the diagrams that contribute to Compton scattering off a
relativistic composite system. These contributions can be derived for
$N$--particle bound states described by the covariant Bethe--Salpeter equation
with a method equivalent to minimal substitution in the one--particle case and
yield the correct contributions (including subtraction terms) in the order
${\cal O}(e^2)$. We give the Ward--Takahashi identities for the general
two--photon vertex as well as the corresponding constraints for the two--photon
irreducible interaction kernel and the Bethe--Salpeter amplitude describing the
bound state. From this we can show that gauge invariance holds for the full
two--photon vertex. We furthermore study in detail the low--energy limit of the
Compton scattering tensor in this approach (including a discussion of the pole
terms) and can prove that the full amplitude yields the correct Born--Thomson
limit as we shall explicitly show for the spin--0 case.
  The calculations are completed by the investigation of certain approximations
that can be formulated for arbitrary $N$--particle bound states. We neglect for
instance contributions from $n$--photon irreducible interaction kernels and
show that in this case gauge invariance is only realized if either the
interaction kernel in the Bethe--Salpeter equation is independent of the total
momentum and additionally is of local type, or if the photon energies vanish;
furthermore, we find the correct low--energy limit in this approximation. To
clarify our approach, we also give the results in the order ${\cal O} (e)$; as
examples, we will quote some resulting lowest order expressions for a $q\bar q$
system explicitly.


title:
Coulomb Distortion in Quasielastic $(e,e')$ Scattering on Nuclei:
  Effective Momentum Approximation and Beyond

abstract:
  The role of the effective momentum approximation to disentangle Coulomb
distortion effects in quasielastic $(e,e')$ reactions is investigated. The
separation of the cross section in longitudinal and transverse components is
discussed including higher order DWBA corrections due to the focusing of the
electron waves.The experimental studies performed, in the last few years,
making use of different approximate treatments are shown to be sometime
inconsistent. As a consequence some of the longitudinal and transverse
responses, extracted from the inclusive cross sections cannot be considered
reliable. A separation procedure based on the effective momentum approximation
is discussed in connection with the recent experimental data on
electron/positron quasielastic scattering on $^{12}$C and $^{208}$Pb.


title:
Wobbling Motion in the multi-bands crossing region: dynamical coupling
  mode between high- and low-K states

abstract:
  We analyze a mechanism of coupling of high- and low-$K$ bands in terms of a
dynamical treatment for nuclear rotations, i.e.,wobbling motion. The wobbling
states are produced through the generator coordinate method after angular
momentum projection ({\it GCM-after-AMP}), in which the intrinsic states are
constructed through fully self-consistent calculations by the 2d-cranked (or
tilted-axis-cranked) HFB method . In particular, the phenomena of ``signature
inversion'' and ``signature splitting'' in the t-band (tilted rotational band)
are explained in terms of the wobbling model. % Our calculations will be
compared with new data for in-band E2 transition rates in $^{182}$Os, which may
shed light on the mechanism of the anomalous K=25 isomer decay, directly to the
yrast band.


title: Molecular-orbital structure in neutron-rich C isotopes

abstract:
  The molecule-like structure of the C isotopes (A=12, 14, 16) is investigated
using a microscopic $\alpha+\alpha+\alpha+n+n+\cdot \cdot \cdot$ model. The
valence neutrons are classified based on the molecular-orbit (MO) model, and
both $\pi$-orbit and $\sigma$-orbit are introduced around three
$\alpha$-clusters. The valence neutrons which occupy the $\pi$-orbit increase
the binding energy and stabilize the linear-chain of 3$\alpha$ against the
breathing-like break-up. However, $^{14}$C with the $\pi$-orbit does not show
clear energy minimum against the bending-like path. The combination of the
valence neutrons in the $\pi$- and the $\sigma$-orbit is promising to stabilize
the linear-chain state against the breathing- and bending- modes, and it is
found that the excited states of $^{16}$C with the
$(3/2^-_\pi)^2(1/2^-_\sigma)^2$ configuration for the four valence neutrons is
one of the most promising candidates for such structure.


title:
Comparison of Dirac and microscopic Schrodinger optical model potentials
  for nucleon-nucleus scattering

abstract:
  Detailed comparisons are made between results of calculations for
intermediate energy nucleon--208Pb scattering using optical potentials obtained
from Dirac phenomenology and a microscopic Schrodinger model. The two
approaches yield quite similar results for all of the observables with each
projectile, including spin observables, suggesting the two models are
physically equivalent. A new phenomenon in the analyzing power is confirmed in
the results for 100 MeV scattering.


title: Changes in r-process abundances at late times

abstract:
  We explore changes in abundance patterns that occur late in the r process. As
the neutrons available for capture begin to disappear, a quasiequilibrium
funnel shifts material into the large peaks at A=130 and A=195, and into the
rare-earth "bump" at A=160. A bit later, after the free-neutron abundance has
dropped and beta-decay has begun to compete seriously with neutron capture, the
peaks can widen. The degree of widening depends largely on neutron-capture
rates near closed neutron shells and relatively close to stability. We identify
particular nuclei the capture rates of which should be examined experimentally,
perhaps at a radioactive beam facility.


title: Gluon self-energy in a two-flavor color superconductor

abstract:
  The energy and momentum dependence of the gluon self-energy is investigated
in a color superconductor with two flavors of massless quarks. The presence of
a color-superconducting quark-quark condensate modifies the gluon self-energy
for energies which are of the order of the gap parameter. For gluon energies
much larger than the gap, the self-energy assumes the form given by the
standard hard-dense loop approximation. It is shown that this modification of
the gluon self-energy does not affect the magnitude of the gap to leading and
subleading order in the weak-coupling limit.


title: Chiral Symmetry in Charmonium - Pion Cross Section

abstract:
  We perform a non-perturbative calculation of the $J/\Psi-\pi$ cross section
using a $SU(2)\times SU(2)$ effective Lagrangian. Our results differ from those
of previous calculations, specially in the description of vertices involving
pions.


title: Strange decays from strange resonances

abstract:
  We discuss the mass spectrum and strong decays of baryon resonances belonging
to the N, Delta, Sigma, Lambda, Xi and Omega families in a collective
string-like model for the nucleon. We find good overall agreement with the
available data. Systematic discrepancies are found for lowlying S-wave states,
in particular in the strong decays of N(1535), N(1650), Sigma(1750),
Lambda(1405), Lambda(1670) and Lambda(1800).


title: Extend Brown-Rho Scaling Law with QCD Sum Rules

abstract:
  The scalar and vector self-energies obtained through QCD sum rules are
introduced in Quantum Hadrodynamics (QHD) equations. The results indicate that
the ratios of coupling constants to respective meson mass have a very small
dependence on density. Then, an extended Brown-Rho scaling law is conjectured.


title:
Relativistic Hartree-Bogoliubov Calculation of Specific Heat of the
  Inner Crust of Neutron Stars

abstract:
  We calculate the specific heat of the inner crust of neutron stars within a
local-density approximation to an improved relativistic Hartree-Bogoliubov
theory. Non-uniformness of the system enhances the specific heat in particular
at low temperatures. The degree of enhancement is similar to that in the
spherical phase of Elgar{\o}y et al. We examine a schematic interpolation
between the results of Broglia et al. adopting the Gogny force and ours based
on the Lagrangian of the relativistic mean field model.


title: Kaonic modes in hyperonic matter and p-wave kaon condensation

abstract:
  Kaon excitations (kaonic modes) are investigated in hyperonic matter, where
hyperons ($\Lambda$, $\Sigma^-$, $\Xi^-$) are mixed in the ground state of
neutron-star matter. $P$-wave kaon-baryon interactions as well as the s-wave
interactions are taken into account within chiral effective Lagrangian, and the
nonrelativistic effective baryon-baryon interactions are incorporated. When the
hyperon $\Lambda$ is more abundant than the proton at high baryon density, a
proton-particle-$\Lambda$-hole mode, which has the $K^+$ quantum number,
appears in addition to other particle-hole modes with the $K^-$ quantum number.
It is shown that the system becomes unstable with respect to a spontaneous
creation of a pair of the particle-hole modes with $K^+$ and $K^-$ quantum
numbers, stemming from the p-wave kaon-baryon interaction. The onset density of
this p-wave kaon condensation may be lower than that of the s-wave $K^-$
condensation.


title: The sigma meson and chiral restoration in nuclear medium

abstract:
  After giving brief discussions on the chiral condensate in hot and/or dense
hadronic matter and the significance of the $\sigma$ meson in QCD, we discuss
the importance of experiments using nuclear targets including ones with
electro-magnetic probes for obtaining clearer confirmation of the existence of
the $\sigma$ meson and for exploring the possible restoration of chiral
symmetry in nuclear medium.


title: Off shell behaviour of the in medium nucleon-nucleon cross section

abstract:
  The properties of nucleon-nucleon scattering inside dense nuclear matter are
investigated. We use the relativistic Brueckner-Hartree-Fock model to determine
on-shell and half off-shell in-medium transition amplitudes and cross sections.
At finite densities the on-shell cross sections are generally suppressed. This
reduction is, however, less pronounced than found in previous works. In the
case that the outgoing momenta are allowed to be off energy shell the
amplitudes show a strong variation with momentum. This description allows to
determine in-medium cross sections beyond the quasi-particle approximation
accounting thereby for the finite width which nucleons acquire in the dense
nuclear medium. For reasonable choices of the in-medium nuclear spectral width,
i.e. $\Gamma\leq 40$ MeV, the resulting total cross sections are, however,
reduced by not more than about 25% compared to the on-shell values. Off-shell
effect are generally more pronounced at large nuclear matter densities.


title: Polarization observables in p-d scattering below 30 MeV

abstract:
  Differential and total breakup cross sections as well as vector and tensor
analyzing powers for p-d scattering are studied for energies above the deuteron
breakup threshold up to E(lab)=28 MeV. The p-d scattering wave function is
expanded in terms of the correlated hyperspherical harmonic basis and the
elastic S-matrix is obtained using the Kohn variational principle in its
complex form. The effects of the Coulomb interaction, which are expected to be
important in this energy range, have been rigorously taken into account. The
Argonne AV18 interaction and the Urbana URIX three-nucleon potential have been
used to perform a comparison to the available experimental data.


title: Vector Meson Decay of Baryon Resonances

abstract:
  We investigate the coupling of vector mesons with nucleons to nucleon
resonances in an isospin-selective VMD approach and explore the in-medium
properties of vector mesons.


title:
The Giessen Model - Vector Meson Production on the Nucleon in a Coupled
  Channel Approach

abstract:
  In this paper we present the extension of our unitary gauge invariant
effective Lagrangian model to vector meson nucleon final states. This model
already included the final states $\gamma N$, $\pi N$, $2\pi N$, $\eta N$, $K
\Lambda$, and $K \Sigma$ and was developed for a simultaneous analysis of all
avaible experimental data for photon- and pion-induced reactions on the
nucleon. We discuss how the extension to vector meson nucleon final states is
realized, outline a generalization of the standard partial wave formalism, that
is applicable to any meson-/photon-baryon reaction, and show first results for
$\omega N$ production.


title:
Prolate dominance of nuclear shape caused by a strong interference
  between the effects of spin-orbit and l^2 terms of the Nilsson potential

abstract:
  The origin of the dominance of prolate shapes over oblate ones of the ground
states of atomic nuclei is investigated with the Nilsson-Strutinsky method. The
number of prolate nuclei among all the deformed even-even nuclei is calculated
as a function of the strengths of the spin-orbit and the l^2 terms of the
Nilsson potential. The latter simulates a square-well like radial profile of
the mean potential. The ratio of prolate nuclei is 86% with the standard
strengths corresponding to the actual atomic nuclei. By weakening the
spin-orbit potential, the ratio oscillates strongly, having a local minimum
value of 45% with a half of the standard strength and a local maximum value of
78% without the spin-orbit potential.


title:
Baryonic contributions to the dilepton spectrum of nucleon-nucleon
  collisions

abstract:
  We study the production of dileptons in relativistic nucleon-nucleon
collisions. Additionally to the traditional dilepton production channels
(vector meson decays, meson and Delta(1232) Dalitz decays) we included in our
model as new dilepton sources the Dalitz decay of higher unflavored baryon
resonances with spin<=5/2 and mass<=2.25 GeV/c^2. The contributions of these
new channels are estimated using experimental information about the Ngamma
decays of the resonances and have large uncertainties. The obtained dilepton
spectra are compared to the experimental data by the DLS collaboration.
Predictions for the HADES detector (SIS, GSI) are also discussed. In spite of
the large uncertainties of the higher resonance Dalitz decay contributions we
are able to draw the conclusion that these contributions are negligible
compared to the other dilepton sources and do not influence the detectability
of the phi and omega vector meson peaks.


title: p_T-fluctuations in high-energy p-p and A-A collisions

abstract:
  The event-by-event p_T-fluctuations in proton-proton and central Pb-Pb
collisions, which have been experimentally studied by means of the so-called
Phi-measure, are analyzed. The contribution due to the correlation which
couples the average p_T to the event multiplicity is computed. The correlation
appears to be far too weak to explain the preliminary experimental value of Phi
(p_T) in p-p interactions. The significance of the result is discussed.


title:
Degeneracies when T=0 Two Body Interacting Matrix Elements are Set Equal
  to Zero : Talmi's method of calculating coefficients of fractional parentage
  to states forbidden by the Pauli principle

abstract:
  In a previous work we studied the effects of setting all two body T=0 matrix
elements to zero in shell model calculations for $^{43}$Ti ($^{43}$Sc) and
$^{44}$Ti. The results for $^{44}$Ti were surprisingly good despite the
severity of this approximation. In this approximation degeneracies arose in the
T=1/2 I=$({1/2})^-_1$ and $({13/2})^-_1$ states in $^{43}$Sc and the T=1/2
$I=({13/2})_2^-$, $({17/2})^-_1$, and $({19/2})_1^-$ in $^{43}$Sc. The T=0
$3_2^+$, $7_2^+$, $9_1^+$, and $10_1^+$ states in $^{44}$Ti were degenerate as
well. The degeneracies can be explained by certain 6j symbols and 9j symbols
either vanishing or being equal as indeed they are. Previously we used Regge
symmetries of 6j symbols to explain these degeneracies. In this work a simpler
more physical method is used. This is Talmi's method of calculating
coefficients of fractional parentage for identical particles to states which
are forbidden by the Pauli principle. This is done for both one particle cfp to
handle 6j symbols and two particle cfp to handle 9j symbols. The states can be
classified by the dual quantum numbers ($J_{\pi},J_{\nu}$).


title: Shell stabilization of super- and hyperheavy nuclei without magic gaps

abstract:
  Quantum stabilization of superheavy elements is quantified in terms of the
shell-correction energy. We compute the shell correction using self-consistent
nuclear models: the non-relativistic Skyrme-Hartree-Fock approach and the
relativistic mean-field model, for a number of parametrizations. All the forces
applied predict a broad valley of shell stabilization around Z=120 and
N=172-184. We also predict two broad regions of shell stabilization in
hyperheavy elements with N approx 258 and N approx 308. Due to the large
single-particle level density, shell corrections in the superheavy elements
differ markedly from those in lighter nuclei. With increasing proton and
neutron numbers, the regions of nuclei stabilized by shell effects become
poorly localized in particle number, and the familiar pattern of shells
separated by magic gaps is basically gone.


title:
A simple functional form for proton-${}^{208}$Pb total reaction cross
  sections

abstract:
  A simple functional form has been found that gives a good representation of
the total reaction cross sections for the scattering from ${}^{208}$Pb of
protons with energies in the range 30 to 300 MeV.


title: E2 and M1 strengths in heavy deformed nuclei

abstract:
  Energy levels of the four lowest bands in 160,162,164Dy and 168Er, B(E2)
transition strengths between the levels, and the B(M1) strength distribution of
the ground state, all calculated within the framework of pseudo-SU(3) model,
are presented. Realistic single-particle energies and quadrupole-quadrupole and
pairing interaction strengths fixed from systematics were used in the
calculations. The strengths of four rotor-like terms, all small relative to the
other terms in the interaction, were adjusted to give an overall best fit to
the energy spectra. The procedure yielded consistent parameter sets for the
four nuclei.


title: Effects of neutron-proton interaction in doubly odd deformed nuclei

abstract:
  We have investigated the effects of the neutron-proton interaction in several
doubly odd deformed nuclei within the framework of the particle-rotor model. In
this paper, we show some selected results of our study which evidence the
importance of the tensor-force effects.


title: Spin ordering of nuclear spectra from random interactions

abstract:
  Recent developments in many-body quantum chaos have raised the issue of
correlations between different families of levels in the spectra of random
fermionic systems. It seems that rotational invariance is sufficient to force
an otherwise random system to have statistically ordered spectra where the
ground state can have zero spin or the maximum spin allowed a huge portion of
the time. We have tackled this question and have characterized the role of
``geometric chaoticity'' and pairing in random systems. We have shown how the
geometry gives rise to such a distribution of ground state spins and examined
the coexistence of these regularities with chaotic wave functions.


title:
Nuclear binding energies: Global collective structure and local
  shell-model correlations

abstract:
  Nuclear binding energies and two-neutron separation energies are analyzed
starting from the liquid-drop model and the nuclear shell model in order to
describe the global trends of the above observables. We subsequently
concentrate on the Interacting Boson Model (IBM) and discuss a new method in
order to provide a consistent description of both, ground-state and
excited-state properties. We address the artefacts that appear when crossing
mid-shell using the IBM formulation and perform detailed numerical calculations
for nuclei situated in the 50-82 shell. We also concentrate on local deviations
from the above global trends in binding energy and two-neutron separation
energies that appear in the neutron-deficient Pb region. We address possible
effects on the binding energy, caused by mixing of low-lying $0^{+}$ intruder
states into the ground state, using configuration mixing in the IBM framework.
We also study ground-state properties using a deformed mean-field approach.
Detailed comparisons with recent experimental data in the Pb region are amply
discussed.