title:
The Anapole Moment of the Deuteron with the Argonne v18 Nucleon-Nucleon
  Interaction Model

abstract:
  We calculate the deuteron anapole moment with the wave functions obtained
from the Argonne $v18$ nucleon-nucleon interaction model. The anapole moment
operators are considered at the leading order. To minimize the uncertainty due
to a lack of current conservation, we calculate the matrix element of the
anapole moment from the original definition. In virtue of accurate wave
functions, we can obtain a more precise value of the deuteron anapole moment
which contains less uncertainty than the former works. We obtain a result
reduced by more than 25% in the magnitude of the deuteron anapole moment. The
reduction of individual nuclear contributions is much more important however,
varying from a factor 2 for the spin part to a factor 4 for the convection and
associated two-body currents.


title: Anisotropic multi-gap superfluid states in nuclear matter

abstract:
  It is shown that under changing density or temperature a nucleon Fermi
superfluid can undergo a phase transition to an anisotropic superfluid state,
characterized by nonvanishing gaps in pairing channels with singlet-singlet
(SS) and triplet-singlet (TS) pairing of nucleons (in spin and isospin spaces).
In the SS pairing channel nucleons are paired with nonzero orbital angular
momentum. Such two-gap states can arise as a result of branching from the
one-gap solution of the self-consistent equations, describing SS or TS pairing
of nucleons, that depends on the relationship between SS and TS coupling
constants at the branching point. The density/temperature dependence of the
order parameters and the critical temperature for transition to the anisotropic
two-gap state are determined in a model with the SkP effective interaction. It
is shown that the anisotropic SS-TS superfluid phase corresponds to a
metastable state in nuclear matter.


title: Entrance-channel potentials in the synthesis of the heaviest nuclei

abstract:
  Entrance-channel potentials in nucleus-nucleus collisions, relevant for the
synthesis of superheavy elements, are systematically studied within a
semi-microscopic approach, where microscopic nuclear densities of the colliding
spherical or deformed nuclei are used in semi-classical expressions of the
energy-density functional. From experimental data on fusion windows evidence is
found that the existence of pockets in the entrance-channel potentials is
crucial for fusion. Criteria for the choice of best collision systems for the
synthesis of superheavy elements are discussed.


title:
A Mathematica Notebook for Alpha Decay Using an Exponentially Diffuse
  Boundary Potential

abstract:
  Using the exponentially diffuse boundary potential of Green and Lee (1955),
we develop a Mathematica notebook to treat alpha decay by using the complex
energy approach of Preston (1947), as modified by Pierronne and Marquez (1978).
Our approach allows the potential to change slowly from the well depth of the
interior of the nucleus to the top of the Coulomb barrier, rather than the
sudden step of the simple square well used by Pierronne and Marquez. Recent
interest in possible variation in coupling constants such as the strong
coupling alpha_s motivates us to develop this algorithm which can allow
numerical study of the variation of the decay constant of a nucleus such as
U-238 when the depth of the nuclear potential well changes.


title:
Matching the QCD and Hadron Sectors and Medium Dependent Meson Masses;
  Hadronization in Relativistic Heavy Ion Collisions

abstract:
  The recent developments on the "vector manifestation" of chiral symmetry by
Harada and Yamawaki provide a compelling evidence for, and "refine," the
in-medium scaling of hadronic properties in dense/hot matter (call it ``BR
scaling") proposed by the authors in 1991. We reinterpret the Harada-Yamawaki
result obtained in a Wilsonian renormalization-group approach to hidden local
symmetry theory matched to QCD at near the chiral scale in terms of the
Nambu-Jona-Lasinio model and predict that the vector meson mass in medium
should scale $m_\rho^\star/m_\rho\sim
(\la\bar{q}q\ra^\star/\la\bar{q}q\ra)^{1/2}$ from $n=0$ up to $\sim n=n_0$
(where $n_0$ is nuclear matter density) and then go over to the linear scaling
$m_\rho^\star/m_\rho\sim \la\bar{q}q\ra^\star/\la\bar{q}q\ra$ up to the chiral
transition density $n_c$ at which the mass is to vanish (in the chiral limit)
according to the vector manifestation fixed point. In the regime of the linear
scaling above $n_0$, the (vector) gauge coupling constant should fall linearly
in $\la\bar{q}q\ra^\star$, vanishing at the critical point, with the width of
the vector meson becoming steeply narrower. We suggest the in-medium vector
meson mass, {\em both} parametric and pole, which goes smoothly to zero with
increasing density, to be an order parameter for chiral symmetry restoration.
Some issues related to recent RHIC observations are qualitatively discussed in
the appendices. Our main conclusion that follows from these considerations is
that the movement towards chiral restoration can be reliably described in
Nambu-Jona-Lasinio mean field, with constituent quarks as variables, although
there is probably density discontinuity following chiral restoration.


title: Projected shell model study of odd-odd f-p-g shell proton-rich nuclei

abstract:
  A systematic study of 2-quasiparticle bands of the proton-rich odd-odd nuclei
in the mass A ~ 70-80 region is performed using the projected shell model
approach. The study includes Br-, Rb-, and Y-isotopes with N = Z+2, and Z+4. We
describe the energy spectra and electromagnetic transition strengths in terms
of the configuration mixing of the angular-momentum projected
multi-quasiparticle states. Signature splitting and signature inversion in the
rotational bands are discussed and are shown to be well described. A
preliminary study of the odd-odd N = Z nucleus, 74Rb using the concept of
spontaneous symmetry breaking is also presented.


title: Hadrons in the Nuclear Medium-Role of Light Front Nuclear Theory

abstract:
  The problem of understanding the nuclear effects observed in lepton-nucleus
deep-inelastic-scattering (the EMC effect) is still with us. Standard nuclear
models (those using only hadronic degrees of freedom) are not able to account
for the EMC effect. Thus it is necessary to understand how the nuclear medium
modifies quark wave functions in the nucleus. Possibilities for such
modifications, represented by the quark meson coupling model, and the
suppression of point-like-configurations are discussed, and methods to
experimentally choose between these are reviewed.


title: $\eta$ bound states in nuclei

abstract:
  The energies and widths of bound states of the $\eta$ meson in different
nuclei are obtained using the results for its selfenergy in a nuclear medium,
which is evaluated in a selfconsistent manner using techniques of unitarized
chiral perturbation theory. We find bound states in all studied nuclei (from
$^{12}{C}$ on) and the half widths obtained are larger than the separation of
the levels, what makes the experimental observation of peaks unlikely. We have
paid a special attention to the region of nuclei where only the $1s$ state
appears and the binding energies are of the order of magnitude of the half
width, which would magnify the chances that some broad peak could be observed.
This is found in the region of $^{24}{Mg}$ with a binding energy around 12.6
MeV and half width of 16.7 MeV. In heavy nuclei like $^{208}{Pb}$ there are
many bound states which would be difficult to disentangle and the deepest state
has a binding energy about 21 MeV and half width around 16 MeV. Such an
overlapping accumulation of states could be seen as an extension of the
continuum of $\eta$ strength into the bound region in $\eta$ production
experiments.


title: Microscopic Nuclear Structure Based upon a Chiral NN Potential

abstract:
  We report on shell-model calculations employing effective interactions
derived from a new realistic nucleon-nucleon (NN) potential based on chiral
effective field theory. We present results for 18O, 134Te, and 210Po. Our
results are in excellent agreement with experiment indicating a remarkable
predictive power of the chiral NN potential for low-energy microscopic nuclear
structure.


title:
Constraints on Two-Body Axial Currents from Reactor
  Antineutrino-Deuteron Breakup Reactions

abstract:
  We discuss how to reduce theoretical uncertainties in the neutrino-deuteron
breakup cross-sections crucial to the Sudbury Neutrino Observatory's efforts to
measure the solar neutrino flux. In effective field theory, the dominant
uncertainties in all neutrino-deuteron reactions can be expressed through a
single, common, isovector axial two-body current parameterized by $L_{1,A}$.
After briefly reviewing the status of fixing $L_{1,A}$ experimentally, we
present a constraint on $L_{1,A}$ imposed by existing reactor
antineutrino-deuteron breakup data. This constraint alone leads to an
uncertainty of 6-7% at 7 MeV neutrino energy in the cross-sections relevant to
the Sudbury Neutrino Observatory. However, more significantly for the Sudbury
experiment, the constraint implies an uncertainty of only 0.7% in the ratio of
charged to neutral current cross-sections used to verify the existence of
neutrino oscillations, at the same energy. This is the only direct experimental
constraint from the two-body system, to date, of the uncertainty in these
cross-sections.


title:
The Electromagnetic Form Factors of the Proton and Neutron: Fundamental
  Indicators of Nucleon Structure

abstract:
  We present a relativistic interpretation for why the proton's ratio of
electric to magnetic form factor falls and for why the ratio of the Pauli to
Dirac form factor varies as 1/Q. Reproducing the observed electric form factor
of the neutron then mandates the inclusion of the effects of the pion cloud.


title: The di-Omega in the extended quark delocalization, color screening model

abstract:
  The Omega-Omega (SIJ=-6,0,0) dibaryon state is studied with the extended
quark-delocalization color-screening model including a pi meson exchange tail,
which reproduces the properties of the deuteron quantitatively. We find the
mass of the di-Omega to be about 45 MeV lower than the Omega-Omega threshold.
The effect of channel coupling due to the tensor force has been calculated and
found to be small in this case. We have also studied the effect of other
pseudoscalar meson exchanges and sensitivity to the short-range cutoff radius,
r_0, for the meson exchanges.


title:
Relativistic mean-field approximation with density-dependent screening
  meson masses in nuclear matter

abstract:
  The Debye screening masses of the $\sigma$, $\omega$ and neutral $\rho$
mesons and the photon are calculated in the relativistic mean-field
approximation. As the density of the nucleon increases, all the screening
masses of mesons increase. It shows a different result with Brown-Rho scaling,
which implies a reduction in the mass of all the mesons in the nuclear matter
except the pion. Replacing the masses of the mesons with their corresponding
screening masses in Walecka-1 model, five saturation properties of the nuclear
matter are fixed reasonably, and then a density-dependent relativistic
mean-field model is proposed without introducing the non-linear self-coupling
terms of mesons.


title: Signatures of Nucleon Disappearance in Large Underground Detectors

abstract:
  For neutrons bound inside nuclei, baryon instability can manifest itself as a
decay into undetectable particles (e.g., $\it n \to \nu \nu \bar{\nu} $), i.e.,
as a disappearance of a neutron from its nuclear state. If electric charge is
conserved, a similar disappearance is impossible for a proton. The existing
experimental lifetime limit for neutron disappearance is 4-7 orders of
magnitude lower than the lifetime limits with detectable nucleon decay products
in the final state [PDG2000]. In this paper we calculated the spectrum of
nuclear de-excitations that would result from the disappearance of a neutron or
two neutrons from $^{12}$C. We found that some de-excitation modes have
signatures that are advantageous for detection in the modern high-mass,
low-background, and low-threshold underground detectors, where neutron
disappearance would result in a characteristic sequence of time- and
space-correlated events. Thus, in the KamLAND detector [Kamland], a
time-correlated triple coincidence of a prompt signal, a captured neutron, and
a $\beta^{+}$ decay of the residual nucleus, all originating from the same
point in the detector, will be a unique signal of neutron disappearance
allowing searches for baryon instability with sensitivity 3-4 orders of
magnitude beyond the present experimental limits.


title: A consistent approximation scheme beyond RPA for bosons

abstract:
  In this paper, we develop a consistent extension of RPA for bosonic systems.
In order to illustrate the method, we consider the case of the anharmonic
oscillator. We compare our results with those obtained in mean-field and
standard RPA approaches, with the exact ones and show that they are very close
to the exact ones.


title:
Triple-Pomeron Matrix Model for Dispersive Corrections to
  Nucleon-Nucleus Total Cross Section

abstract:
  Dispersive corrections to the total cross section for high-energy scattering
from a heavy nucleus are calculated using a matrix model, based on the
triple-Pomeron behavior of diffractive scattering from a single nucleon, for
the cross section operator connecting different states of the projectile
nucleon . Energy-dependent effects due to the decrease in longitudinal momentum
transfers and the opening of more channels with increasing energy are included.
The three leading terms in an expansion in the number of inelastic transitions
are evaluated and compared to exact results for the model in the uniform
nuclear density approximation for the the scattering of nucleons from Pb^{208}
for laboratory momenta ranging from 50 to 200 GeV/c.


title:
Multipole Amplitudes of Pion Photoproduction on Nucleons up to 2GeV
  within Dispersion Relations and Unitary Isobar Model

abstract:
  Two approaches for analysis of pion photo- and electroproduction on nucleons
in the resonance energy region are checked at $Q^2=0$ using the results of
GWU(VPI) partial-wave analysis of photoproduction data. The approaches are
based on dispersion relations and unitary isobar model. Within dispersion
relations good description of photoproduction multipoles is obtained up to
$W=1.8 GeV$. Within unitary isobar model, modified with increasing energy by
incorporation of Regge poles, and with unified Breit-Wigner parametrization of
resonance contributions, good description of photoproduction multipoles is
obtained up to $W=2 GeV$.


title: $\pi\omega\rho$ vertex in nuclear matter

abstract:
  Medium modifications of the $\pi \omega \rho$ vertex are analyzed in context
of the $\omega \to \pi^0 \gamma^\ast$ and $\rho \to \pi \gamma^\ast$ decays in
nuclear matter. A relativistic hadronic model with mesons, nucleons, and
$\Delta(1232)$ isobars is applied. A substantial increase of the widths for the
decays $\omega \to \pi^0 \gamma^\ast$ and $\rho \to \pi \gamma^\ast$ is found
for photon virtualities in the range $0.3-0.6$GeV. This enhancement has a
direct importance for the description of dilepton yields from dalitz decays in
relativistic heavy-ion collisions.


title: Folding model analysis of alpha radioactivity

abstract:
  Radioactive decay of nuclei via emission of $\alpha$ particles has been
studied theoretically in the framework of a superasymmetric fission model using
the double folding (DF) procedure for obtaining the $\alpha$-nucleus
interaction potential. The DF nuclear potential has been obtained by folding in
the density distribution functions of the $\alpha$ nucleus and the daughter
nucleus with a realistic effective interaction. The M3Y effective interaction
has been used for calculating the nuclear interaction potential which has been
supplemented by a zero-range pseudo-potential for exchange along with the
density dependence. The nuclear microscopic $\alpha$-nucleus potential thus
obtained has been used along with the Coulomb interaction potential to
calculate the action integral within the WKB approximation. This subsequently
yields microscopic calculations for the half lives of $\alpha$ decays of
nuclei. The density dependence and the exchange effects have not been found to
be very significant. These calculations provide reasonable estimates for the
lifetimes of $\alpha$ radioactivity of nuclei.


title:
Erratum: Neutron and proton spectra from the decay of $\Lambda$
  hypernuclei [Phys. Rev. C55, 735 (1997)]

abstract:
  An error in the computer program which evaluated nucleon spectra following
the decay of $\Lambda$ hypernuclei has been detected. The error affected the
final state interaction (FSI) of the nucleons, reducing by a factor ten the
nucleon-nucleon (NN) collision probability. When correcting the error, some
results and conclusions of Ref. [1] have changed substantially.


title: Pionic Atom Formation in Halo Nuclei by (d,3He) Reactions

abstract:
  We investigate the formation cross sections of the deeply bound pionic atoms
on halo nuclei theoretically. We consider one-neutron pick-up (d,3He) reaction
for the pionic atom formation and find that the formation rate is significantly
increased by the existence of the halo neutron with long tail of the wave
function. This enhancement is expected to increase the experimental feasibility
for the formation of the deeply bound pionic states on beta-unstable nuclei.


title: Interaction of $\eta$ mesons with a three-nucleon system

abstract:
  A study of the $\eta$-3N interaction in the energy region near the $\eta$-^3H
elastic scattering threshold is presented. The calculational scheme is based on
the four-body scattering formalism. A manageable form of the integral equations
is achieved by using a separable ansatz for the driving two-body $\eta N$- and
NN-forces as well as for the subamplitudes appearing in the (1+3) and (2+2)
partitions of the $\eta$-3N system. Results presented for the $\eta$-^3H
scattering length point to the existence of a virtual (antibound) s-wave
$\eta$-^3H state. As a consequence, a large enhancement of the cross section
for $\eta$-production from three-body nuclei is predicted.


title: Induced pseudoscalar coupling of the proton weak interaction

abstract:
  The induced pseudoscalar coupling $g_p$ is the least well known of the weak
coupling constants of the proton's charged--current interaction. Its size is
dictated by chiral symmetry arguments, and its measurement represents an
important test of quantum chromodynamics at low energies. During the past
decade a large body of new data relevant to the coupling $g_p$ has been
accumulated. This data includes measurements of radiative and non radiative
muon capture on targets ranging from hydrogen and few--nucleon systems to
complex nuclei. Herein the authors review the theoretical underpinnings of
$g_p$, the experimental studies of $g_p$, and the procedures and uncertainties
in extracting the coupling from data. Current puzzles are highlighted and
future opportunities are discussed.


title:
Many-body Systems Interacting via a Two-body Random Ensemble (I):
  Angular Momentum distribution in the ground states

abstract:
  In this paper, we discuss the angular momentum distribution in the ground
states of many-body systems interacting via a two-body random ensemble.
Beginning with a few simple examples, a simple approach to predict P(I)'s,
angular momenta I ground state (g.s.) probabilities, of a few solvable cases,
such as fermions in a small single-j shell and d boson systems, is given. This
method is generalized to predict P(I)'s of more complicated cases, such as even
or odd number of fermions in a large single-j shell or a many-j shell, d-boson,
sd-boson or sdg-boson systems, etc. By this method we are able to tell which
interactions are essential to produce a sizable P(I) in a many-body system. The
g.s. probability of maximum angular momentum $I_{max}$ is discussed. An
argument on the microscopic foundation of our approach, and certain matrix
elements which are useful to understand the observed regularities, are also
given or addressed in detail. The low seniority chain of 0 g.s. by using the
same set of two-body interactions is confirmed but it is noted that
contribution to the total 0 g.s. probability beyond this chain may be more
important for even fermions in a single-j shell. Preliminary results by taking
a displaced two-body random ensemble are presented for the I g.s.
probabilities.


title:
Many-body Systems Interacting via a Two-body Random Ensemble: average
  energy of each angular momentum

abstract:
  In this paper, we discuss the regularities of energy of each angular momentum
$I$ averaged over all the states for a fixed angular momentum (denoted as
$\bar{E}_I$'s) in many-body systems interacting via a two-body random ensemble.
It is found that $\bar{E}_I$'s with $I \sim I_{min}$ (minimum of $I$) or
$I_{max}$ have large probabilities (denoted as ${\cal P}(I)$) to be the lowest,
and that ${\cal P}(I)$ is close to zero elsewhere. A simple argument based on
the randomness of the two-particle cfp's is given. A compact trajectory of the
energy $\bar{E}_I$ vs. $I(I+1)$ is found to be robust. Regular fluctuations of
the $P(I)$ (the probability of finding $I$ to be the ground state) and ${\cal
P}(I)$ of even fermions in a single-$j$ shell and boson systems are found to be
reverse, and argued by the dimension fluctuation of the model space. Other
regularities, such as why there are 2 or 3 sizable ${\cal P}(I)$'s with $I\sim
I_{min}$ and ${\cal P}(I) \ll {\cal P}(I_{max})$'s with $I\sim I_{max}$, why
the coefficients $C$ defined by $<\bar{E}_I >$=$CI(I+1)$ is sensitive to the
orbits and not sensitive to particle number, are found and studied for the
first time.


title: Generic Rotation in a Collective SD Nucleon-Pair Subspace

abstract:
  Low-lying collective states involving many nucleons interacting by a random
ensemble of two-body interactions (TBRE) are investigated in a collective
SD-pair subspace, with the collective pairs defined dynamically from the
two-nucleon system. It is found that in this truncated pair subspace collective
vibrations arise naturally for a general TBRE hamiltonian whereas collective
rotations do not. A hamiltonian restricted to include only a few randomly
generated separable terms is able to produce collective rotational behavior, as
long as it includes a reasonably strong quadrupole-quadrupole component.
Similar results arise in the full shell model space. These results suggest that
the structure of the hamiltonian is key to producing generic collective
rotation.


title: Medium effects to N(1535) resonance and eta mesic nuclei

abstract:
  The structure of eta-nucleus bound systems (eta mesic nuclei) is investigated
as one of the tools to study in-medium properties of the N(1535) (N^*)
resonance by using the chiral doublet model to incorporate the medium effects
of the N^* resonance in a chiral symmetric way. We find that the shape and the
depth of the eta-nucleus optical potential are strongly affected by the
in-medium properties of the N^* and the nucleon. Especially, as a general
feature of the potential, the existence of a repulsive core of the eta-nucleus
potential at the nuclear center with an attractive part at the nuclear surface
is concluded. We calculate the level structure of bound states in this
'central-repulsive and surface-attractive' optical potential and find that the
level structure is sensitive to the in-medium properties of the N^*. The
(d,3He) spectra are also evaluated for the formation of these bound states to
investigate the experimental feasibility. We also make comments on the possible
existence of halo-like eta states in beta-unstable halo nuclei.


title:
Parity nonconservation effects in the photodesintegration of polarized
  deuterons

abstract:
  P-odd correlations in the deuteron photodesintegration are considered. The
$\pi$-meson exchange is not operative in the case of unpolarized deuterons. For
polarized deuterons a P-odd correlation due to the $\pi$-meson exchange is
about $3 \times 10^{-9}$. Short-distance P-odd contributions exceed essentially
than the contribution of the $\pi$-meson exchange.


title: Isospin-rich nuclei in neutron star matter

abstract:
  Stability of nuclei beyond the drip lines in the presence of an enveloping
gas of nucleons and electrons, as prevailing in the inner crust of a neutron
star, is studied in the temperature-dependent Thomas-Fermi framework. A
limiting asymmetry in the isospin space beyond which nuclei cannot exist
emerges from the calculations. The ambient conditions like temperature, baryon
density and neutrino concentration under which these exotic nuclear systems can
be formed are studied in some detail.


title:
Anisotropic flow of strange particles in heavy ion collisions at RHIC
  energies

abstract:
  Anisotropic flow of K's, anti-K's, and lambdas is studied in heavy ion
collisions at SPS and RHIC energies within the microscopic quark-gluon string
model. At SPS energy the directed flow of kaons differs considerably at
midrapidity from that of antikaons, while at RHIC energy kaon and antikaon
flows coincide. The change is attributed to formation of dense meson-dominated
matter at RHIC, where the differences in interaction cross-sections of hadrons
become unimportant. The directed flows of strange particles, $v_1^{K,\bar{K},
\Lambda}(y)$, have universal negative slope at $|y| \leq 2$ at RHIC. The
elliptic flow of strange hadrons is developed at midrapidity at times 3<t<10
fm/c. It increases almost linearly with rising p_t and stops to rise at p_t <
1.5 GeV/c reaching the same saturation value $v_2 ^{K,\Lambda}(p_t) \approx
10%$ in accord with experimental results.


title: Equation of state of quark-nuclear matter

abstract:
  Quark-nuclear matter (QNM) is a many-body system containing hadrons and
deconfined quarks. Starting from a microscopic quark-meson coupling (QMC)
Hamiltonian with a density dependent quark-quark interaction, an effective
quark-hadron Hamiltonian is constructed via a mapping procedure. The mapping is
implemented with a unitary operator such that composites are redescribed by
elementary-particle field operators that satisfy canonical commutation
relations in an extended Fock space. Application of the unitary operator to the
microscopic Hamiltonian leads to effective, hermitian operators that have a
clear physical interpretation. At sufficiently high densities, the effective
Hamiltonian contains interactions that lead to quark deconfinement. The
equation of state of QNM is obtained using standard many-body techniques with
the effective quark-hadron Hamiltonian. At low densities, the model is
equivalent to a QMC model with confined quarks. Beyond a critical density, when
quarks start to deconfine, the equation of state predicted for QNM is softer
than the QMC equation of state with confined quarks.


title:
Heuristic Models of Two-Fermion Relativistic Systems with Field-Type
  Interaction

abstract:
  We use the chain of simple heuristic expedients to obtain perturbative and
exactly solvable relativistic spectra for a family of two-fermionic bound
systems with Coulomb-like interaction. In the case of electromagnetic
interaction the spectrum coincides up to the second order in a coupling
constant with that following from the quantum electrodynamics. Discrepancy
occurs only for S-states which is the well-known difficulty in the bound-state
problem. The confinement interaction is considered too.
  PACS number(s): 03.65.Pm, 03.65.Ge, 12.39.Pn


title: Lattice Calculation of Baryon Masses using the Clover Fermion Action

abstract:
  We present a calculation of the lowest-lying baryon masses in the quenched
approximation to QCD. The calculations are performed using a non-perturbatively
improved clover fermion action, and a splitting is found between the masses of
the nucleon and its parity partner. An analysis of the mass of the first radial
excitation of the nucleon finds a value considerably larger than that of the
parity partner of the nucleon, and thus little evidence for the Roper resonance
as a simple three-quark state


title: Local scale transformations and extended matter distributions in nuclei

abstract:
  Local scale transformations are made to vary the long range properties of
harmonic oscillator orbitals conventionally used in model structure
calculations of nuclear systems. The transformations ensure that those
oscillator states asymptotically have exponentially decaying forms consistent
with chosen single nucleon binding energies, leaving the structure essentially
unchanged within the body of the nucleus. Application has been made to the
radioactive nuclei 6,8He and 11Li and the resulting wave functions are used to
generate g-folding optical potentials for elastic scattering of those ions from
hydrogen. As a consistency test, application has been made to form wave
functions for 40Ca and they have been used also to specify relevant proton-40Ca
optical potentials with which elastic scattering has been predicted. The need
for appropriate specifications of single particle binding energies in exotic
nuclei is discussed.


title:
Inflation of fireballs, the gluon wind and the homogeneity of the HBT
  radii at RHIC

abstract:
  We solve analytically the ellipsoidally expanding fireball hydrodynamics with
source terms in the momentum and the energy equations, using the
non-relativistic approximation. We find that energy transport from high pt jets
of gluons to the medium leads to a transient, exponential inflation of the
fireballs created in high energy heavy ion collisions. In this transient,
inflatory period, the slopes of the single particle spectra increase, while the
HBT radius parameters decrease exponentially with time. This effect is shown to
be similar to the development of the homogeneity of our Universe due to an
inflatory period. Independently of the initial conditions, and the exact value
of the freeze-out time and temperature, the meausurables (single particle
spectra, the correlation functions, the slope parameters, elliptic flow, HBT
radii and cross terms) become time independent during the late, non-inflatory
stages of the expansion, and they satisfy new kind of scaling laws. If the
expansion starts with a transient inflation caused by the gluon wind, it leads
naturally to large transverse flows and the simultaneous equality and scaling
behaviour of the HBT radius parameters, R_{side} \approx R_{out} \approx
R_{long} \approx t_f \sqrt{T_f/m}. With certain relativistic corrections, the
scaling limit is \tau_f \sqrt{T_f/m_t}, where m_t is the mean transverse mass
of the pair.


title: Mean $p_t$ fluctuations from 2- and 4-particle correlations

abstract:
  Recent results on event-by-event mean transverse momentum, $\mpt$,
fluctuations in ultra-relativistic heavy ion collisions are briefly reviewed.
We conclude that the observed fluctuations are in a rough agreement with that
expected for the independent superposition of nucleon-nucleon collisions. We
further discuss the possibility of the use of the forth order cumulants of the
particle transverse momentum distribution in order to access the fluctuations
related to collective phenomena.


title:
High Density Behaviour of Nuclear Symmetry Energy and High Energy
  Heavy-Ion Collisions

abstract:
  High energy heavy-ion collisions are proposed as a novel means to obtain
information about the high density ({\rm HD}) behaviour of nuclear symmetry
energy. Within an isospin-dependent hadronic transport model using
phenomenological equations of state ({\rm EOS}) for dense neutron-rich matter,
it is shown that the isospin asymmetry of the HD nuclear matter formed in high
energy heavy-ion collisions is determined mainly by the HD behaviour of nuclear
symmetry energy. Experimental signatures in several sensitive probes, i.e.,
$\pi^-$ to $\pi^+$ ratio, transverse collective flow and its excitation
function as well as neutron-proton differential flow, are investigated. A
precursor of the possible isospin separation instability in dense neutron-rich
matter is predicted to appear as the local minima in the excitation functions
of the transverse flow parameter for both neutrons and protons above the pion
production threshold. Because of its {\it qualitative} nature unlike other {\it
quantitative} observables, this precursor can be used as a unique signature of
the isospin dependence of the nuclear {\rm EOS}. Measurements of these
observables will provide the first terrestrial data to constrain stringently
the HD behaviour of nuclear symmetry energy and thus also the {\rm EOS} of
dense neutron-rich matter. Implications of our findings to neutron star studies
are also discussed.


title:
Fragmentation of Nuclei at Intermediate and High Energies in Modified
  Cascade Model

abstract:
  The process of nuclear multifragmentation has been implemented, together with
evaporation and fission channels of the disintegration of excited remnants in
nucleus-nucleus collisions using percolation theory and the intranuclear
cascade model. Colliding nuclei are treated as face--centered--cubic lattices
with nucleons occupying the nodes of the lattice. The site--bond percolation
model is used. The code can be applied for calculation of the fragmentation of
nuclei in spallation and multifragmentation reactions.


title: The sigma meson in a nuclear medium through two pion photoproduction

abstract:
  We present theoretical results for (gamma,pi0 pi0) and (gamma,pi+- pi0)
production on nucleons and nuclei in the kinematical region where the scalar
isoscalar pi pi amplitude is influenced by the sigma pole. The final state
interaction of the pions modified by the nuclear medium produces a spectacular
shift of strength of the pi0 pi0 invariant mass distribution induced by the
moving of the sigma pole to lower masses and widths as the nuclear density
increases.


title: Nuclear spin-orbit interaction from chiral pion-nucleon dynamics

abstract:
  Using the two-loop approximation of chiral perturbation theory, we calculate
the momentum and density dependent nuclear spin-orbit strength $U_{ls}(p,k_f)$.
This quantity is derived from the spin-dependent part of the interaction energy
$\Sigma_{spin} = {i\over 2} \vec \sigma \cdot (\vec q \times\vec p)
U_{ls}(p,k_f)$ of a nucleon scattering off weakly inhomogeneous isospin
symmetric nuclear matter. We find that iterated $1\pi$-exchange generates at
saturation density, $k_{f0}=272.7 $MeV, a spin-orbit strength at $p=0$ of
$U_{ls}(0,k_{f0})\simeq 35$ MeVfm$^2$ in perfect agreement with the empirical
value used in the shell model. This novel spin-orbit strength is neither of
relativistic nor of short range origin. The potential $V_{ls}$ underlying the
empirical spin-orbit strength $\widetilde U_{ls}= V_{ls} r_{ls}^2$ becomes a
rather weak one, $V_{ls}\simeq 17$ MeV, after the identification $r_{ls}=
m_\pi^{-1}$ as suggested by the present calculation. We observe however a
strong $p$-dependence of $U_{ls}(p,k_{f0})$ leading even to a sign change above
$p=200 $MeV. This and other features of the emerging spin-orbit Hamiltonian
which go beyond the usual shell model parametrization leave questions about the
ultimate relevance of the spin-orbit interaction generated by $2\pi$-exchange
for a finite nucleus. We also calculate the complex-valued isovector
single-particle potential $U_I(p,k_f)+ i W_I(p,k_f)$ in isospin asymmetric
nuclear matter proportional to $\tau_3 (N-Z)/(N+Z)$. For the real part we find
reasonable agreement with empirical values and the imaginary part vanishes at
the Fermi-surface $p=k_f$.


title:
Excitation modes of $^{11}$Li at E$_x \sim$ 1.3 MeV from proton
  collisions

abstract:
  The cross section for p-$^{11}$Li inelastic scattering at 68 MeV/u is
evaluated using the Multiple Scattering expansion of the total Transition
amplitude (MST) formalism, and compared with the breakup in the shakeoff
approximation. Three different potential models for $^{11}$Li are used to
calculate the $^{11}$Li(p,p$'$) continuum excitations, and all show peaks below
3 MeV of excitation energy, both in resonant and some non-resonant channels. In
the most realistic model of $^{11}$Li, there is a strong dipole contribution
associated with attractive but not a fully-fledged resonant phase shifts, and
some evidence for a J$_{nn}^\pi = 0_2^+$ resonant contribution. These together
form a pronounced peak at around 1--2 MeV excitation, in agreement with
experiment, and this supports the use of the MST as an adequate formalism to
study excited modes of two-neutron nuclear halos.


title:
Fission-Fragment Mass Distribution and Particle Evaporation at low
  Energies

abstract:
  Fusion-fission dynamics is investigated with a special emphasis on fusion
reactions at low energy for which shell effects and pairing correlations can
play a crucial role leading in particular to multi-modal fission. To follow the
dynamical evolution of an excited and rotating nucleus we solve a 2-dimensional
Langevin equation taking explicitly light-particle evaporation into account.
The confrontation theory-experiment is demonstrated to give interesting
information on the model presented, its qualities as well as its shortcomings.


title: Quasiparticle RPA with finite rank approximation for Skyrme interactions

abstract:
  A finite rank separable approximation for the particle-hole RPA calculations
with Skyrme interactions is extended to take into account the pairing. As an
illustration of the method energies and transition probabilities for the
quadrupole and octupole excitations in some O, Ar, Sn and Pb isotopes are
calculated. The values obtained within our approach are very close to those
that were calculated within QRPA with the full Skyrme interaction. They are in
reasonable agreement with experimental data.


title: Tracking the phase-transition energy in disassembly of hot nuclei

abstract:
  In efforts to determine phase transitions in the disintegration of highly
excited heavy nuclei, a popular practice is to parametrise the yields of
isotopes as a function of temperature in the form
$Y(z)=z^{-\tau}f(z^{\sigma}(T-T_0))$, where $Y(z)$'s are the measured yields
and $\tau, \sigma$ and $T_0$ are fitted to the yields. Here $T_0$ would be
interpreted as the phase transition temperature. For finite systems such as
those obtained in nuclear collisions, this parametrisation is only approximate
and hence allows for extraction of $T_0$ in more than one way. In this work we
look in detail at how values of $T_0$ differ, depending on methods of
extraction. It should be mentioned that for finite systems, this approximate
parametrisation works not only at the critical point, but also for first order
phase transitions (at least in some models). Thus the approximate fit is no
guarantee that one is seeing a critical phenomenon. A different but more
conventional search for the nuclear phase transition would look for a maximum
in the specific heat as a function of temperature $T_2$. In this case $T_2$ is
interpreted as the phase transition temperature. Ideally $T_0$ and $T_2$ would
coincide. We invesigate this possibility, both in theory and from the ISiS
data, performing both canonical ($T$) and microcanonical ($e=E^*/A$)
calculations. Although more than one value of $T_0$ can be extracted from the
approximate parmetrisation, the work here points to the best value from among
the choices. Several interesting results, seen in theoretical calculations, are
borne out in experiment.


title: Quantum Monte Carlo calculations of $A=9,10$ nuclei

abstract:
  We report on quantum Monte Carlo calculations of the ground and low-lying
excited states of $A=9,10$ nuclei using realistic Hamiltonians containing the
Argonne $v_{18}$ two-nucleon potential alone or with one of several
three-nucleon potentials, including Urbana IX and three of the new Illinois
models. The calculations begin with correlated many-body wave functions that
have an $\alpha$-like core and multiple p-shell nucleons, $LS$-coupled to the
appropriate $(J^{\pi};T)$ quantum numbers for the state of interest. After
optimization, these variational trial functions are used as input to a Green's
function Monte Carlo calculation of the energy, using a constrained path
algorithm. We find that the Hamiltonians that include Illinois three-nucleon
potentials reproduce ten states in $^9$Li, $^9$Be, $^{10}$Be, and $^{10}$B with
an rms deviation as little as 900 keV. In particular, we obtain the correct
3$^+$ ground state for $^{10}$B, whereas the Argonne $v_{18}$ alone or with
Urbana IX predicts a 1$^+$ ground state. In addition, we calculate isovector
and isotensor energy differences, electromagnetic moments, and one- and
two-body density distributions.


title:
Heavy ion collisions at intermediate energies in a quark-gluon exchange
  framework

abstract:
  Heavy ion collisions at intermediate energies can be studied in the context
of the Vlasov-Uehling-Uhlenbeck (VUU) model. One of the main features in this
model is the nucleon-nucleon (NN) cross section in the collisional term. Quark
interchange plays a role in the NN interaction and its effect can be observed
in the cross section. We explore the possibility that quark interchange effects
can appear in observables at energies lower than RHIC.


title:
Effects of the difference between the charge and matter deformations on
  fusion reactions of unstable nuclei

abstract:
  Relativistic mean field calculations suggest that the charge and matter
deformations significantly differ in some of the unstable neutron and proton
rich nuclei. We discuss the effects of the difference on the fusion reactions
induced by them at energies near and below the Coulomb barrier by taking the
$^{19,25,37}$Na + $^{208}$Pb reactions as examples. We also discuss whether one
can probe the difference by the so called fusion barrier distribution analysis.


title:
Low Energy Proton-Deuteron Scattering with a Coulomb-Modified Faddeev
  Equation

abstract:
  A modified version of the Faddeev three-body equation to accommodate the
Coulomb interaction, which was used in the study of three-nucleon bound states,
is applied to the proton-deuteron scattering problem at energies below the
three-body breakup threshold. A formal derivation of the equation in a
time-independent scattering theory is given. Numerical results for phase shift
parameters are presented to be compared with those of another methods and
results of the phase shift analysis. Differential cross sections and nucleon
analyzing powers are calculated with the effects of three-nucleon forces, and
these results are compared with recent experimental data. The difference
between the nucleon analyzing power in proton-deuteron scattering and that in
neutron-deuteron scattering is discussed.


title:
Semiclassical evaluation of average nuclear one and two body matrix
  elements

abstract:
  Thomas-Fermi theory is developed to evaluate nuclear matrix elements averaged
on the energy shell, on the basis of independent particle Hamiltonians. One-
and two-body matrix elements are compared with the quantal results and it is
demonstrated that the semiclassical matrix elements, as function of energy,
well pass through the average of the scattered quantum values. For the one-body
matrix elements it is shown how the Thomas-Fermi approach can be projected on
good parity and also on good angular momentum. For the two-body case the
pairing matrix elements are considered explicitly.


title:
$\pi NN^*(1440)$ and $\sigma NN^*(1440)$ coupling constants from a
  microscopic $NN \to NN^*(1440)$ potential

abstract:
  By means of a $NN \to NN^*(1440)$ transition potential derived in a
parameter-free way from a quark model, we determined simultaneously the $\pi
NN^*(1440)$ and $\sigma NN^*(1440)$ coupling constants.


title: Mass Number Dependence of Nuclear Pairing

abstract:
  Large scale Hartree-Fock-Bogoliubov (HFB) calculations with the finite-range
  Gogny force D1S have been performed in order to extract the corresponding
theoretical average mass dependence of the nuclear gap values. Good agreement
with experimental data from the three-point filter
  $\Delta^{(3)}$(N) with N odd has been found for both the neutron and proton
gaps. The study confirms earlier findings [W. Satula,
  J. Dobaczewski, and W. Nazarewicz, Phys. Rev. Lett. 81 3599 (1998)] that the
mass dependence of the gap is much weaker than the so far accepted 12/$\sqrtA$
MeV law.


title: Effets de structure dans la diffusion des ions lourds

abstract:
  Nous avons analyse les distributions angulaires de la diffusion elastique
pour differents systemes a des energies proches de la barriere de Coulomb au
moyen d'un potentiel semi phenomenologique. Les distributions radiales
calculees au moyen de ces potentiels montrent sans ambiguite qu'aux energies
proches de la barriere de Coulomb, l'absorption se produit dans un etroit
domaine de distances de la surface du potentiel nucleaire. Utilisant une
modelisation simple de la theorie de Feshbach du potentiel optique, nous avons
calcule la contribution a l'absorption due a un nombre reduit d'etats
collectifs de surface facilement excitables. L'inclusion d'un terme
d'absorption phenomenologique pour decrire des processus plus peripheriques que
les excitations inelastiques, nous a permis de reproduire de maniere
satisfaisante les distributions angulaires experimentales de la diffusion
elastique. Aux plus hautes energies (793 MeV et 1503 MeV), et pour le systeme
16O+208Pb, nous avons utilise un potentiel reel obtenu moyennant une
modelisation simple de la relation de dispersion et nous avons fait usage du
modele de fermeture propose par N. Vinh Mau pour calculer le terme d'absorption
du potentiel. Nos calculs a 793 MeV conduisent a des resultats identiques a
ceux obtenus avec les potentiels de reference. Par contre a 1503 MeV, les
calculs ne reproduisent pas convenablement les donnees experimentales indiquant
qu'a cette energie l'absorption n'est plus controlee par les seuls processus
collectifs.


title:
Quadrupole resonances in unstable oxygen isotopes in time-dependent
  density-matrix formalism

abstract:
  The strength functions of quadrupole modes in the unstable oxygen isotopes
22O and 24O are calculated using an extended version of the time-dependent
Hartree-Fock theory known as the time-dependent density-matrix theory (TDDM).
It is found that TDDM gives the lowest quadrupole states which are
energetically shifted upward and become significantly collective due to the
coupling to two-body configurations. It is pointed out that these features of
the lowest quadrupole states are similar to those obtained in the
quasi-particle random phase approximation.


title: On the analytic solution of the pairing problem: one pair in many levels

abstract:
  We search for approximate, but analytic solutions of the pairing problem for
one pair of nucleons in many levels of a potential well. For the collective
energy a general formula, independent of the details of the single particle
spectrum, is given in both the strong and weak coupling regimes. Next the
displacements of the solutions trapped in between the single particle levels
with respect to the unperturbed energies are explored: their dependence upon a
suitably defined quantum number is found to undergo a transition between two
different regimes.


title: Baryonic masses based on the NJL model

abstract:
  We employ the Nambu Jona--Lasinio model to determine the vacuum pressure on
the quarks in a baryon and hence their density inside. Then we estimate the
baryonic masses by implementing the local density approximation for the mean
field quark energies obtained in a uniform and isotropic system. We obtain a
fair agreement with the experimental masses.


title:
Direct neutron capture cross sections of 62Ni in the s-process energy
  range

abstract:
  Direct neutron capture on 62Ni is calculated in the DWBA and the cross
sections in the energy range relevant for s-process nucleosynthesis are given.
It is confirmed that the thermal value of the capture cross section contains a
subthreshold resonance contribution. Contrary to previous investigations it is
found that the capture at higher energies is dominated by p-waves, thus leading
to a considerably increased cross section at s-process energies and a modified
energy dependence.


title: High energy nuclear interactions and QCD: an introduction

abstract:
  The goal of these lectures, oriented towards the students just entering the
field, is to provide an elementary introduction to QCD and the physics of
nuclear interactions at high energies. We first introduce the general structure
of QCD and discuss its main properties. Then we proceed to Glauber multiple
scattering theory which lays the foundation for the theoretical treatment of
nuclear interactions at high energies. We introduce the concept of Gribov's
inelastic shadowing, crucial for the understanding of quantum formation
effects. We outline the problems facing Glauber approach at high energies, and
discuss how asymptotic freedom of QCD helps to resolve them, introducing the
concepts of parton saturation and color glass condensate.


title: Final state interaction in semi-inclusive DIS off nuclei

abstract:
  The final state interaction in DIS of leptons off a nucleus A, due to the
propagation of the struck nucleon debris and its hadronization in the nuclear
environment is considered. The effective cross section of such a partonic
system with the nucleons of the medium and its time dependence are estimated on
the basis of a model which takes into account the production of hadrons due to
the breaking of the color string and to gluon radiation. It is shown that the
details of the propagation of the partonic system in the nuclear environment
can be thoroughly investigated by the semi-inclusive process A(e,e'(A-1))X, in
which the scattered lepton is detected in coincidence with the nucleus (A-1) in
low energy and momentum states. The rescattering of the struck nucleon debris
with the medium damps and distorts the momentum distributions of (A-1) in a way
which is very sensitive to the details of effective cross section of the
debris.
  The total cross section of the process on ^4He, ^16O, and ^40Ca, related to
the probability that after a target nucleon experiences a DIS process, the
recoiling (A-1) nucleus remains intact, is evaluated, and the distorted
momentum distribution of the recoiling (A-1) system is obtained. It is shown
that both quantities are very sensitive to the details of the early stage of
hadronization of the nucleon debris in the nuclear medium.


title:
Scaling Behavior of $(N_{ch})^{-1}dN_{ch}/d\eta$ at $\sqrt{s_{NN}} =
  130$ GeV by the PHOBOS Collaboration and Its Implication --A Possible
  Explanation Employing the Ornstein-Uhlenbeck Process--

abstract:
  Recently, interesting data concerning $dN_{ch}/d\eta$ in Au-Au collisions
[$\eta=-\ln \tan (\theta/2)$] with centrality cuts have been reported from the
PHOBOS Collaboration. In most treatment these data are divided by the number of
participants (nucleons) in collisions. Instead of this method, we use the total
multiplicity $N_{ch} = \int (dN_{ch}/d\eta)d\eta$ and find that there is
scaling phenomenon among $(N_{ch})^{-1}dN_{ch}/d\eta = dn/d\eta$ with different
centrality cuts at $\sqrt{s_{NN}} = 130$ GeV. To explain this scaling behavior
of $dn/d\eta$, we employ a stochastic approach using the Ornstein-Uhlenbeck
process with two sources. A Langevin equation is adopted for this explanation.
Moreover, comparisons of $dn/d\eta$ at $\sqrt{s_{NN}} = 130$ GeV with that at
$\sqrt{s_{NN}} = 200$ GeV are made, and no significant difference is found. A
possible method fot the detection of the quark-gluon plasma (QGP) through
$dN_{ch}/d\eta$ is presented.


title:
Symmetry constraints for the emission angle dependence of Hanbury
  Brown--Twiss radii

abstract:
  We discuss symmetry constraints on the azimuthal oscillations of two-particle
correlation (Hanbury Brown--Twiss interferometry) radii for non-central
collisions between equal spherical nuclei. We also propose a new method for
correcting in a model-independent way the emission angle dependent correlation
function for finite event plane resolution and angular binning effects.


title:
Renormalization group approach to neutron matter: quasiparticle
  interactions, superfluid gaps and the equation of state

abstract:
  Renormalization group methods can be applied to the nuclear many-body problem
using the approach proposed by Shankar. We start with the two-body low momentum
interaction V_{low k} and use the RG flow from the particle-hole channels to
calculate the full scattering amplitude in the vicinity of the Fermi surface.
This is a new straightforward approach to the many-body problem which is
applicable also to condensed matter systems without long-range interactions,
such as liquid 3He. We derive the one-loop renormalization group equations for
the quasiparticle interaction and the scattering amplitude at zero temperature.
The RG presents an elegant method to maintain all momentum scales and preserve
the antisymmetry of the scattering amplitude. As a first application we solve
the RG equations for neutron matter. The resulting quasiparticle interaction
includes effects due to the polarization of the medium, the so-called induced
interaction of Babu and Brown. We present results for the Fermi liquid
parameters, the equation of state of neutron matter and the 1S0 superfluid
pairing gap.


title:
The nucleon interaction and neutron matter from the renormalization
  group

abstract:
  We show that the renormalization group decimation of modern nucleon potential
models to low momenta results in a unique nucleon interaction V_{low k}. This
interaction is free of short-ranged singularities and can be used directly in
many-body calculations. The RG scaling properties follow directly from the
invariance of the scattering phase shifts. We discuss the RG treatment of Fermi
liquids. The RG equation for the scattering amplitude in the two particle-hole
channels is given at zero temperature. The flow equations are simplified by
retaining only the leading term in an expansion in small momentum transfers.
The RG flow is illustrated by first studying a system of spin-polarized
fermions in a simple model. Finally, results for neutron matter are presented
by employing the unique low momentum interaction V_{low k} as initial condition
of the flow. The RG approach yields the amplitude for non-forward scattering,
which is of great interest for calculations of transport properties and
superfluid gaps in neutron star interiors. The methods used can also be applied
to condensed matter systems in the absence of long-ranged interactions.


title: D mesons in matter and the in-medium properties of charmonium

abstract:
  We study the changes in the partial decay widths of excited charmonium states
into $D \bar{D}$, when the D meson mass decreases in nuclear matter, taking the
internal structure of the hadrons into account. Calculations within the 3P0
model for $\psi(3686)$ and $\psi(3770)$ imply that naive estimates of the
in-medium widths based only on phase space are grossly exaggerated. Due to
nodes in the wave functions, these states may even become narrow at high
densities, if the D meson mass is decreased by about 200 MeV. For the $\chi$
states, we generally expect stronger modifications of the widths. The relevance
of the $\chi$ widths for $J/\psi$ suppression in heavy ion collision is
discussed. These phenomena could be explored in experiments at the future
accelerator facility at GSI.


title: Light Front Cloudy Bag Model: Nucleon Electromagnetic Form Factors

abstract:
  The nucleon is modeled, using light front dynamics, as a relativistic system
of three bound constituent quarks emersed in a cloud of pions. The pionic cloud
is important for understanding low-momentum transfer physics, especially the
neutron charge radius, but the quarks are dominant at large momentum transfer.
The model achieves a very good description of existing data for the four
electromagnetic elastic form factors.


title: Constraints on proton-proton fusion from helioseismology

abstract:
  The proton-proton ($pp$) fusion cross-section found at the heart of solar
models is unconstrained experimentally and relies solely on theoretical
calculations. Effective field theory provides an opportunity to constrain the
$pp$ cross-section experimentally, however, this method is complicated by the
appearance of two-nucleon effects in the form of an unknown parameter
$L_{1,A}$. We present a method to constrain $L_{1,A}$ using the Standard Solar
Model and helioseismology. Using this method, we determine a value of $L_{1,A}$
= 7.0 fm$^{3}$ with a range of 1.6 to 12.4 fm$^{3}$. These results are
consistent with theoretical estimates of $L_{1,A} \approx$ 6 fm$^{3}$.


title: Quark interchange effects in the KN interaction

abstract:
  We study the short range repulsion in the KN system due to quark-gluon
exchange. Phase shifts for spin-spin, color Coloumb and spin-orbit interactions
are presented.


title: Sum rules on quantum hadrodynamics

abstract:
  The development on relativistic nuclear many-body theories is reviewed. The
second order self-energies of hadrons are calculated from $\hat{S}_2$ matrix,
and then an effective method to solve nuclear many-body problems, sum rules on
quantum hadrodynamics, is summarized. The differences between this method and
quantum hadrodynamics are discussed. The effective nucleon mass in the nuclear
matter is redefined in the relativistic Hartree approximation, and a
self-consistent relativistic mean-field model based on quantum hadrodynamics 2
is proposed. It is pointed out that the original definition on effective
nucleon mass in quantum hadrodynamics 2 is not self-consistent, and all the
parameters in the relativistic mean-field approximation should be fixed again
according to the new definition.


title:
Enhanced binding and cold compression of nuclei due to admixture of
  antibaryons

abstract:
  We discuss the possibility of producing a new kind of nuclear system by
putting a few antibaryons inside ordinary nuclei. The structure of such systems
is calculated within the relativistic mean--field model assuming that the
nucleon and antinucleon potentials are related by the G-parity transformation.
The presence of antinucleons leads to decreasing vector potential and
increasing scalar potential for the nucleons. As a result, a strongly bound
system of high density is formed. Due to the significant reduction of the
available phase space the annihilation probability might be strongly suppressed
in such systems.


title:
Hydrodynamic description of spectra at high transverse mass in
  ultrarelativistic heavy ion collisions

abstract:
  Transverse mass spectra of pions and protons measured in central collisions
of heavy ions at the SPS and at RHIC are compared to a hydrodynamic
parameterization. While the chemical temperature needed at RHIC is
significantly higher compared to SPS, the spectra may be described using
kinetic freeze-out parameters which are similar for both beam energies. At RHIC
either the temperature or the flow velocity is higher, but the data provide no
unambiguous proof for much stronger transverse flow. The contribution of such
hydrodynamic emission at high transverse momenta is investigated in detail. It
is shown that hydrodynamics may be relevant up to relatively high transverse
momenta. The importance of the velocity profile used in this context is
highlighted.


title: Tensor correlations in the Unitary Correlation Operator Method

abstract:
  We present a unitary correlation operator that explicitly induces into shell
model type many-body states short ranged two-body correlations caused by the
strong repulsive core and the pronounced tensor part of the nucleon-nucleon
interaction. Alternatively an effective Hamiltonian can be defined by applying
this unitary correlator to the realistic nucleon-nucleon interaction.
  The momentum space representation shows that realistic interactions which
differ in their short range behaviour are mapped on the same correlated
Hamiltonian, indicating a successful provision for the correlations at high
momenta. Calculations for He4 using the one- and two-body part of the
correlated Hamiltonian compare favorably with exact many-body methods. For
heavier nuclei like O16 and Ca40 where exact many-body calculations are not
possible we compare our results with other approximations. The correlated
single-particle momentum distributions describe the occupation of states above
the Fermi momentum. The Unitary Correlation Operator Method (UCOM) can be used
in mean-field and shell model configuration spaces that are not able to
describe these repulsive and tensor correlations explicitly.


title: Flavor ordering of elliptic flows at high transverse momentum

abstract:
  Based on the quark coalescence model for the parton-to-hadron phase
transition in ultra-relativistic heavy ion collisions, we relate the elliptic
flow ($v_2$) of high $\pt$ hadrons to that of high $\pt$ quarks. For high $\pt$
hadrons produced from an isospin symmetric and quark-antiquark symmetric
partonic matter, magnitudes of their elliptic flows follow a flavor ordering as
$(v_{2,\pi}=v_{2,N}) > (v_{2,\Lambda}=v_{2,\Sigma})
  > v_{2,K} > v_{2,\Xi} > (v_{2,\phi}=v_{2,\Omega})$ if strange quarks have a
smaller elliptic flow than light quarks. The elliptic flows of high $\pt$
hadrons further follow a simple quark counting rule if strange quarks and light
quarks have same high $\pt$ spectrum and coalescence probability.


title:
Theoretical understanding of pion production in nucleon-nucleon
  collisions - a status report

abstract:
  A status report is given for the current theoretical understanding of pion
production close to threshold. In the first part of the talk predictions of a
meson exchange model are compared to recent polarized data for the reactions
$pp \to pp\pi^0$ as well as $pp\to pn\pi^+$ revealing, that the former reaction
is badly described whereas the predictions for the latter turn out to be
consistent with the data. Recent progress in the application of chiral
perturbation theory allows to understand this difference.


title:
The reconstructed final state of Au + Au collisions from PHENIX and STAR
  data at sqrt{s}=130 AGeV - indication for quark deconfinement at RHIC

abstract:
  The final state of Au + Au collisions at sqrt{s}=130 AGeV at RHIC has been
reconstructed within the framework of the Buda-Lund hydrodynamical model, by
performing a simultaneous fit to final data on two-particle Bose-Einstein
correlations of the STAR and PHENIX Collaborations, and final identified single
particle spectra as measured by the PHENIX Collaboration. The results indicate
a strongly three-dimensional expansion with a four-velocity field that is
almost a spherically symmetric Hubble flow. We find large transverse
geometrical source sizes, R_G = 9.8 +- 1.2 fm, a relatively short mean
freeze-out time of tau0 = 6.1 +- 0.3 fm/c and a short duration of particle
emission, Delta_tau = 0.02 +- 1.5 fm/c. Most strikingly, we find an indication
for a hot central part or the hydrodynamically evolving core, characterized by
a central temperature of T0 = 202 +- 13 MeV, that is close to (or even above)
the deconfinement temperature of the quark-hadron phase transition. The best
fit indicates a cold surface temperature of T_s = 110 +- 16 MeV. When the
possibility of the hot center is excluded, the confidence level of the fit
decreases from 28.9 % to 1.2 %. Predictions are made for the rapidity
dependence of the slope parameters, for the transverse mass dependence of the
rapidity-width of the single-particle spectra, and for the transverse velocity
dependence of the non-indentical particle correlations.


title: SU(3) versus deformed Hartree-Fock

abstract:
  Deformation is fundamental to understanding nuclear structure. We compare two
ways to efficiently realize deformation for many-fermion wavefunctions, the
leading SU(3) irrep and the angular-momentum projected Hartree-Fock state. In
the absence of single-particle spin-orbit splitting the two are nearly
identical. With realistic forces, however, the difference between the two is
non-trivial, with the angular-momentum projected Hartree-Fock state better
approximating an ``exact'' wavefunction calculated in the fully interacting
shell model. The difference is driven almost entirely by the single-particle
spin-orbit splitting.


title: Anomalous J/psi suppression and charmonium dissociation cross sections

abstract:
  We study $J/\psi$ suppression in Pb+Pb collisions at CERN-SPS energies in
hadronic matter with energy- and temperature-dependent charmonium dissociation
cross sections calculated in the quark-interchange model of Barnes and Swanson.
We find that the variation of J/$\psi$ survival probability from peripheral to
central collisions can be explained as induced by hadronic matter absorption in
central collisions.


title: The Axial-Vector Current in Nuclear Many-Body Physics

abstract:
  Weak-interaction currents are studied in a recently proposed effective field
theory of the nuclear many-body problem. The Lorentz-invariant effective field
theory contains nucleons, pions, isoscalar scalar ($\sigma$) and vector
($\omega$) fields, and isovector vector ($\rho$) fields. The theory exhibits a
nonlinear realization of $SU(2)_L \times SU(2)_R$ chiral symmetry and has three
desirable features: it uses the same degrees of freedom to describe the
axial-vector current and the strong-interaction dynamics, it satisfies the
symmetries of the underlying theory of quantum chromodynamics, and its
parameters can be calibrated using strong-interaction phenomena, like hadron
scattering or the empirical properties of finite nuclei. Moreover, it has
recently been verified that for normal nuclear systems, it is possible to
systematically expand the effective lagrangian in powers of the meson fields
(and their derivatives) and to reliably truncate the expansion after the first
few orders. Here it is shown that the expressions for the axial-vector current,
evaluated through the first few orders in the field expansion, satisfy both
PCAC and the Goldberger--Treiman relation, and it is verified that the
corresponding vector and axial-vector charges satisfy the familiar chiral
charge algebra. Explicit results are derived for the Lorentz-covariant,
axial-vector, two-nucleon amplitudes, from which axial-vector meson-exchange
currents can be deduced.


title:
The $\pi N \to e^+e^- N$ reaction close to the vector meson production
  threshold

abstract:
  The $\pi^-p \to e^+e^- n$ and $\pi^+n \to e^+e^- p$ reaction cross sections
are calculated below and in the vicinity of the vector meson ($\rho^0$,
$\omega$) production threshold. These processes are largely responsible for the
emission of $e^+e^-$ pairs in pion-nucleus reactions and contribute to the
dilepton spectra observed in relativistic heavy ion collisions. They are
dominated by the decay of low-lying baryon resonances into vector meson-nucleon
channels. The vector mesons materialize subsequently into $e^+e^-$ pairs. Using
$\pi N\to \rho^0 N$ and $\pi N \to \omega N$ amplitudes calculated in the
center of mass energy interval $1.4<\sqrt s <1.8$ GeV, we compute the $\pi^-p
\to e^+e^- n$ and $\pi^+n \to e^+e^- p$ reaction cross sections in these
kinematics. Below the vector meson production threshold, the $\rho^0 - \omega$
interference in the $e^+e^-$ channel appears largely destructive for the
$\pi^-p \to e^+e^- n$ cross section and constructive for the $\pi^+n \to e^+e^-
p$ cross section. The pion beam and the HADES detector at GSI offer a unique
possibility to measure these effects. Such data would provide strong
constraints on the coupling of vector meson-nucleon channels to low-lying
baryon resonances.


title: Effective DBHF Method for Asymmetric Nuclear Matter and Finite Nuclei

abstract:
  A new decomposition of the Dirac structure of nucleon self-energies in the
Dirac Brueckner-Hartree-Fock (DBHF) approach is adopted to investigate the
equation of state for asymmetric nuclear matter. The effective coupling
constants of $\sigma $, $\omega $, $\delta $ and $\rho $ mesons with a density
dependence in the relativistic mean field approach are deduced by reproducing
the nucleon self-energy resulting from the DBHF at each density for symmetric
and asymmetric nuclear matter. With these couplings the properties of finite
nuclei are investigated. The agreement of charge radii and binding energies of
finite nuclei with the experimental data are improved simultaneously in
comparison with the projection method. It seems that the properties of finite
nuclei are sensitive to the scheme used for the DBHF self-energy extraction. We
may conclude that the properties of the asymmetric nuclear matter and finite
nuclei could be well described by the new decomposition approach of the G
matrix.


title: Description of 8Be as Deformed Gas-like Two-Alpha-Paricle States

abstract:
  In order to study non-zero spin excitations of the recently proposed
alpha-cluster condensation in the self-conjugate 4n nuclei, spatial deformation
is introduced into the model wave function of the alpha-cluster condensate. The
rotational band states of 8Be are investigated as a first step of a test case
for the study of the deformation of the alpha-cluster condensate. Calculations
reproduce well the binding energy of the 0+ ground state and also the
excitation energy of the 2+ state. Our 0+ wave function is found to be almost
exactly equal to the 0+ wave function obtained by the generator coordinate
method using Brink's 2 alpha wave function. The study shows that both the 0+
ground and 2+ excited states can be considered as having a gas-like (i.e.
weakly bound) 2 alpha-cluster structure. As for the 0+ ground state, the change
of the wave function, due to the introduction of the deformation, is found to
be very small.


title:
Baryon and Antibaryon production at RHIC energies in the Dual Parton
  Model

abstract:
  We compute the mid-rapidity densities of pions, kaons, baryons and
antibaryons in $Au$--$Au$ collisions at $\sqrt{s}$ = 130 GeV in the Dual Parton
Model supplemented with final state interactions, and we present a comparison
with available data.


title:
In-Band and Inter-Band B(E2) Values within the Triaxial Projected Shell
  Model

abstract:
  The Triaxial Projected Shell Model (TPSM) has been successful in providing a
microscopic description of the energies of multi-phonon vibrational bands in
deformed nuclei. We report here on an extension of the TPSM to allow, for the
first time, calculations of B(E2) values connecting gamma- and
gamma-gamma-vibrational bands and the ground state band. The method is applied
to 166,168Er. It is shown that most of the existing B(E2) data can be
reproduced rather well, thus strongly supporting the classification of these
states as gamma-vibrational states. However, significant differences between
the data and the calculation are seen in those B(E2) values which involve
odd-spin states of the gamma-band. Understanding these discrepancies requires
accurate experimental measurements and perhaps further improvements of the
TPSM.


title:
The Density Matrix Renormalization Group Method for Realistic
  Large-Scale Nuclear Shell-Model Calculations

abstract:
  The Density Matrix Renormalization Group (DMRG) method is developed for
application to realistic nuclear systems. Test results are reported for 24Mg.


title:
Dispersion relation analysis of neutral pion photo- and
  electroproduction at threshold using the MAID and SAID solutions

abstract:
  Neutral pion photo- and electroproduction at threshold is analyzed in the
framework of dispersion relations. For this purpose, we evaluate the real
threshold amplitudes in terms of Born contributions and dispersion integrals
determined by the imaginary parts of the MAID and SAID multipoles. The results
show considerable cancellations between Born terms and resonance contributions.
Good agreement with the data is found for photoproduction. While our dispersion
analysis suggests considerable discrepancies for electroproduction, the present
state of the experimental multipole analysis at finite Q^2 does not permit
drawing conclusions at this time.


title: Hybrid and Conventional Baryons in the Flux-Tube Model

abstract:
  Conventional and hybrid light quark baryons are constructed in the
non-relativistic flux-tube model of Isgur and Paton, which is motivated by
lattice QCD. The motion of the flux tube with the three quark positions fixed,
except for center of mass corrections, is discussed. It is shown that the
problem can be reduced to the independent motion of the junction and the
strings connecting the junction to the quarks. The important role played by
quark-exchange symmetry in constraining the flavor structure of (hybrid)
baryons is emphasized. The flavor, quark spin S, total spin J, and parity P of
the seven low-lying hybrid baryons are found to be N2(1/2)+, N2(3/2)+,
Delta4(1/2)+, Delta4(3/2)+, and Delta4(5/2)+, where the notation is
flavor[2S+1](J)P, and the N2(1/2)+ and N2(3/2)+ states are doublets. The motion
of the three quarks in an adiabatic potential derived from the flux-tube
dynamics is considered. A mass of 1870 +/- 100 MeV for the lightest nucleon
hybrids is found by employing a variational method.


title:
Quasi-Local Density Functional Theory and its Application within
  Extended Thomas-Fermi Approximation

abstract:
  A generalization of the Density Functional Theory is proposed. The theory
developed leads to single-particle equations of motion with a quasi-local
mean-field operator, which contains a quasi-particle position-dependent
effective mass and a spin-orbit potential. The energy density functional is
constructed using the Extended Thomas-Fermi approximation. Within the framework
of this approach the ground-state properties of the doubly magic nuclei are
considered. The calculations have been performed using the finite-range Gogny
D1S force. The results are compared with the exact Hartree-Fock calculations.


title: Three-Body approach to the K^- d Scattering Length in Particle Basis

abstract:
  We report on the first calculation of the scattering length A_{K^-d} based on
a relativistic three-body approach where the two-body input amplitudes coupled
to the Kbar N channels have been obtained with the chiral SU(3) constraint, but
with isospin symmetry breaking effects taken into account. Results are compared
with a recent calculation applying a similar set of two-body amplitudes,based
on the fixed center approximation, considered as a good approximation for a
loosely bound target, and for which we find significant deviations from the
exact three-body results. Effects of the hyperon-nucleon interaction, and
deuteron $D$-wave component are also evaluated.


title: Cascade production from antikaon induced reactions on lambda and sigma

abstract:
  Using a gauged flavor SU(3) invariant hadronic Lagrangian, we study $\Xi$
production from $\bar K$ induced reactions on $\Lambda$ and $\Sigma$ in a
coupled-channel approach. Including the four channels of $\bar K\Lambda$, $\bar
K\Sigma$, $\pi\Xi$, and $\eta\Xi$, we solve the Bethe-Salpeter equation in the
$K$-matrix approximation by neglecting the off-shell contribution in the
intermediate states. For the transition potential which drives the higher-order
contribution, we consider all allowed Born diagrams in the $s$, $t$, and $u$
channels. With coupling constants determined from the SU(3) symmetry with
empirical input, we find that the cross sections for the reactions $\bar
K\Lambda\to\pi\Xi$, $\bar K\Sigma\to\pi\Xi$, $\bar K\Lambda\to\eta\Xi$, and
$\bar K\Sigma\to\eta\Xi$ all have values of a few mb. In contrast to the
results from the lowest-order Born approximation, the magnitude of these cross
sections is less sensitive to the values of the cut-off parameters in the form
factors. From the transition matrix in the coupled-channel approach, we have
further evaluated the cross sections for the elastic process $\bar
K\Lambda\to\bar K\Lambda$, $\bar K\Sigma\to\bar K\Sigma$, $\pi\Xi\to\pi\Xi$,
and $\eta\Xi\to\eta\Xi$ as well as for the inelastic processes $\bar
K\Lambda\to\bar K\Sigma$ and $\pi\Xi\to\eta\Xi$. Implications of the reactions
studied here in $\Xi$ production from relativistic heavy ion collisions are
discussed.


title: Note on the Deformed Boson Scheme in Four Kinds of Boson Operators

abstract:
  The deformed boson scheme in four kinds of boson operators, which was
recently proposed by the present authors, is supplemented by the T-type
deformation closely related with the su(1,1)-algebra. Two subjects are
discussed in relation to the S-type deformation closely related with the
su(2)-algebra.


title:
Near-threshold production of $a_0(980)$-mesons in $\pi N$ and NN
  collisions and $a_0/f_0$-mixing

abstract:
  We consider near-threshold $a_0(980)$-meson production in $\pi N$ and $NN$
collisions. An effective Lagrangian approach with one-pion exchange is applied
to analyze different contributions to the cross section for different isospin
channels. The Reggeon exchange mechanism is also evaluated for comparison. The
results from $\pi N$ reactions are used to calculate the contribution of the
$a_0$ meson to the cross sections and invariant $K \bar K$ mass distributions
of the reactions $pp\to pn K^+\bar K^0$ and $pp\to pp K^+K^-$. It is found that
the experimental observation of $a_0^+$ mesons in the reaction $pp\to pn
K^+\bar K^0$ is much more promising than the observation of $a_0^0$ mesons in
the reaction $pp\to pp K^+K^-$. Effects of isospin violation in the reactions
$pN \to d a_0$, $pd \to \mathrm{^3He/^3H} a_0$, and $ dd \to \mathrm{^4He}
a_0$, which are induced by $a_0(980)$--$f_0(980)$ mixing, are also analyzed.


title:
Low Energy Expansion in the Three Body System to All Orders and the
  Triton Channel

abstract:
  We extend and systematise the power counting for the three-body system, in
the context of the ``pion-less'' Effective Field Theory approach, to all orders
in the low-energy expansion. We show that a sub-leading part of the three-body
force appears at the third order and delineate how the expansion proceeds at
higher orders. After discussing the renormalisation issues in a simple bosonic
model, we compute the phase shifts for neutron-deuteron scattering in the
doublet S wave (triton) channel and compare our results with phase shift
analysis and potential model calculations.


title:
A computer program for nuclear scattering at intermediate and high
  energies

abstract:
  A computer program is presented which calculates the elastic and inelastic
scattering in intermediate and high energy nuclear collisions. A
coupled-channels method is used for Coulomb and nuclear excitations of E1, E2,
E3, M1, and M2 multipolarities, respectively. The program applies to an
arbitrary nucleus, specified by the spins and energies of the levels and by
reduced matrix elements. For given bombarding conditions, the angular
distribution of elastic and inelastic scattered particles and angular
distributions of gamma-rays from the excited nucleus are computed.


title:
Properties of charmed and bottom hadrons in nuclear matter: A plausible
  study

abstract:
  Changes in properties of heavy hadrons with a charm or a bottom quark are
studied in nuclear matter. Effective masses (scalar potentials) for the hadrons
are calculated using quark-meson coupling model. Our results also suggest that
the heavy baryons containing a charm or a bottom quark will form charmed or
bottom hypernuclei, which was first predicted in mid 70's. In addition a
possibility of $B^-$-nuclear bound (atomic) states is briefly discussed.


title: Correlation Functions and Cumulants in Elliptic Flow Analysis

abstract:
  We consider various methods of flow analysis in heavy ion collisions and
compare experimental data on corresponding observables to the predictions of
our saturation model proposed earlier. We demonstrate that, due to the nature
of the standard flow analysis, azimuthal distribution of particles with respect
to reaction plane determined from the second order harmonics should always be
proportional to $\cos 2(\phi-\Psi_R)$ independent of the physical origin of
particle correlations (flow or non-flow). The amplitude of this distribution is
always physical and proportional to $v_2$. Two-particle correlations analysis
is therefore a more reliable way of extracting the shape of physical azimuthal
anisotropy. We demonstrate that two-particle correlation functions generated in
our minijet model of particle production are in good agreement with the data
reported by PHENIX. We discuss the role of non-flow correlations in the
cumulant flow analysis and demonstrate using a simple example that if the flow
is weak, higher order cumulants analysis does not significantly reduce the
contribution of non-flow correlations to elliptic flow observable $v_2$ in RHIC
data.


title: Sum Rules for Parity Violating Compton Amplitudes

abstract:
  Sum rules for parity violating spin polarizabilities are derived and
discussed. They hold both for hadron and nuclear stable targets of arbitrary
spin and are exact in strong interactions. Examples of applications to the
cases of proton and deuteron targets are given. The legitimacy of the
dispersive approach in the Standard Model is discussed.


title:
On the equivalence of pairing correlations and intrinsic vortical
  currents in rotating nuclei

abstract:
  The present paper establishes a link between pairing correlations in rotating
nuclei and collective vortical modes in the intrinsic frame. We show that the
latter can be embodied by a simple S-type coupling a la Chandrasekhar between
rotational and intrinsic vortical collective modes. This results from a
comparison between the solutions of microscopic calculations within the HFB and
the HF Routhian formalisms. The HF Routhian solutions are constrained to have
the same Kelvin circulation expectation value as the HFB ones. It is shown in
several mass regions, pairing regimes, and for various spin values that this
procedure yields moments of inertia, angular velocities, and current
distributions which are very similar within both formalisms. We finally present
perspectives for further studies.


title:
New parameterization of the trinucleon wavefunction and its application
  to the $\pi^3$He scattering length

abstract:
  We present a new parameterization of the trinucleon wavefunction. As a novel
feature a separable parameterization for the complete wavefunction is given. In
this way any calculation that considers two body forces only is largely
simplified. To demonstrate this we calculate the $\pi^3$He scattering length.


title: A relativistic parton cascade with radiation

abstract:
  We consider the evolution of a parton system which is formed at the central
rapidity region just after an ultrarelativistic heavy ion collision. The
evolution of the system, which is composed of gluons, quarks and antiquarks, is
described by a relativistic Boltzmann equations with collision terms including
radiation and retardation effects. The equations are solved by the test
particle method using Monte-Carlo sampling. Our simulations do not show any
evidence of kinetic equilibration, unless the cross sections are artificially
increased to unrealistically large values.


title: Parton rescattering and screening in Au+Au collisions at RHIC

abstract:
  We study the microscopic dynamics of quarks and gluons in relativistic heavy
ion collisions in the framework of the Parton Cascade Model. We use lowest
order perturbative QCD cross sections with fixed lower momentum cutoff p_0. We
calculate the time-evolution of the Debye-screening mass for Au+Au collisions
at sqrt(s)=200 GeV per nucleon pair. The screening mass is used to determine a
lower limit for the allowed range of p_0. We also determine the energy density
reached through hard and semi-hard processes at RHIC, obtain a lower bound for
the rapidity density of charged hadrons produced by semihard interactions, and
analyze the extent of perturbative rescattering among partons.


title: Exotic Structure of Carbon Isotopes

abstract:
  We studied firstly the ground state properties of C-isotopes using a deformed
Hartree-Fock (HF)+ BCS model with Skyrme interactions. Shallow deformation
minima are found in several neutron$-$rich C-isotopes. It is shown also that
the deformation minima appear in both the oblate and the prolate sides in
$^{17}$C and $^{19}$C having almost the same binding energies. Secondly, we
carried out shell model calculations to study electromagnetic moments and
electric dipole transitions of the C-isotopes. We point out the clear
configuration dependence of the quadrupole and magnetic moments in the odd
C-isotopes, which will be useful to find out the deformations and the
spin-parities of the ground states of these nuclei. We studied electric dipole
states of C-isotopes focusing on the interplay between low energy Pigmy
strength and giant dipole resonances.
  Reasonable agreement is obtained with available experimental data for the
photoreaction cross sections both in the low energy region below $\hbar \omega
$=14 MeV and in the high energy giant resonance region (14 MeV $<\hbar \omega
\leq $30 MeV).
  The calculated transition strength below dipole giant resonance ($\hbar
\omega \leq $14 MeV) in heavier C-isotopes than $^{15}$C is found to exhaust
about $12\sim16%$ of the classical Thomas-Reiche-Kuhn sum rule value and
$50\sim80%$ of the cluster sum rule value.


title:
Cranked Skyrme-Hartree-Fock calculation for superdeformed and
  hyperdeformed rotational bands in N=Z nuclei from 32S to 48Cr

abstract:
  With the use of the symmetry-unrestricted cranked Skyrme-Hartree-Fock method
in the three-dimensional coordinate-mesh representation, we have carried out a
systematic theoretical search for the superdeformed and hyperdeformed
rotational bands in the mass A=30-50 region. Along the N=Z line, we have found
superdeformed solutions in 32S, 36Ar, 40Ca, 44Ti, and hyperdeformed solutions
in 36Ar, 40Ca, 44Ti, 48Cr. The superdeformed band in 40Ca is found to be
extremely soft against both the axially symmteric (Y30) and asymmetric (Y31)
octupole deformations. An interesting role of symmetry breaking in the mean
field is pointed out.


title: Low-energy photodisintegration of $^9$Be with the molecular orbit model

abstract:
  We use a microscopic three-cluster model with the $\alpha+\alpha+n$
configuration to analyze with astrophysical interests the photodisintegration
cross section of $^9$Be. The valence neutron in $^9$Be is treated in the
molecular orbit model (MO), including continuum states by the box
discretization method. It is shown that good agreement is achieved with the
recently measured B(E1) transition probability from the ground state to the
first 1/2$^+$ state when the box size is enlarged, resulting in reasonable
reproduction of the experimental data for the photodisintegration cross
section. The Coulomb dissociation of $^9$Be is also discussed.


title: Charge symmetry breaking in pion production

abstract:
  Chiral effective field theory predicts a charge symmetry violating (CSB)
amplitude for pion-nucleon scattering. This mechanism provides a very large
contribution also to the CSB forward-backward asymmetry in the angular
distribution of the reaction pn --> d pi0. This contribution was so large that
it had a potential to cause a large effect also in CSB elastic NN scattering
and to disturb its present understanding. However, it can be seen that,
contrary to pion production, in this case the ud-quark mass difference and the
electromagnetic contribution to the np-mass difference tend to cancel causing
the total effect in the effective range parameters Delta a = a_pp - a_nn and
Delta r_0 = r_0,pp - r_0,nn to be relatively small. In the lowest order and
within the static approximation for the nucleons CSB pion-nucleon rescattering
does not influence np scattering.


title:
Toy Model for Pion Production II: The role of three-particle
  singularities

abstract:
  The influence of three-particle breakup singularities on s-wave meson
production in nucleon-nucleon collisions is studied within the distorted wave
Born approximation. This study is based on a simple scalar model for the
two-nucleon interaction and the production mechanism. An algorithm for the
exact numerical treatment of the inherent three-body cuts, together with its
straightforward implementation is presented. It is also shown that two
often-used approximations to avoid the calculation of the three-body breakup
are not justified. The possible impact on pion production observables is
discussed.


title: An Alternative Parameterization of R-matrix Theory

abstract:
  An alternative parameterization of R-matrix theory is presented which is
mathematically equivalent to the standard approach, but possesses features
which simplify the fitting of experimental data. In particular there are no
level shifts and no boundary-condition constants which allows the positions and
partial widths of an arbitrary number levels to be easily fixed in an analysis.
These alternative parameters can be converted to standard R-matrix parameters
by a straightforward matrix diagonalization procedure. In addition it is
possible to express the collision matrix directly in terms of the alternative
parameters.


title:
Coherence Effects in Charmonium Production off Nuclei : Consequences for
  J/\psi Suppression

abstract:
  The probabilistic Glauber formula for nuclear absorption used in the
literature is only valid at low energies and $x_+ \simeq 0$. Due to energy
conservation, $\sigma_{abs}$ is replaced by an effective cross-section
$\sigma_{abs} + x_+^{\gamma}$ ($\sigma_{c\bar{c}-N} - \sigma_{abs})$ which
increases with $x_+$ and tends to the total $c\bar{c}-N$ cross-section
$\sigma_{c\bar{c}-N}$. Experimental data can be described with $\sigma_{abs}
\sim 4 \div 5$mb and $\sigma_{c\bar{c}-N} \sim 15 \div 20$mb. At high energies,
due to the increase of the coherence length, this formula changes. The main
change is the replacement of $\sigma_{abs}$ by $\sigma_{c\bar{c}-N}$ -- for all
values of $x_+$, as $s \to \infty$. Thus, if $\sigma_{c\bar{c}-N} >
\sigma_{abs}$ the $J/\psi$ suppression due to nuclear interaction will increase
with energy.


title: Evolution of Nuclear Spectra with Nuclear Forces

abstract:
  We first define a series of NN interaction models ranging from very simple to
fully realistic. We then present Green's function Monte Carlo calculations of
light nuclei to show how nuclear spectra evolve as the nuclear forces are made
increasingly sophisticated. We find that the absence of stable five- and
eight-body nuclei depends crucially on the spin, isospin, and tensor components
of the nuclear force.


title: Isospin Fluctuations from a Thermally Equilibrated Hadron Gas

abstract:
  Partition functions, multiplicity distributions, and isospin fluctuations are
calculated for canonical ensembles in which additive quantum numbers as well as
total isospin are strictly conserved. When properly accounting for
Bose-Einstein symmetrization, the multiplicity distributions of neutral pions
in a pion gas are significantly broader as compared to the non-degenerate case.
Inclusion of resonances compensates for this broadening effect. Recursion
relations are derived which allow calculation of exact results with modest
computer time.


title: Photoproduction of the Eta Meson from the Deuteron Near Threshold

abstract:
  Very recent data for the reaction gamma{d} --> eta{np} are analyzed within a
model that includes contributions from the impulse approximation and next order
corrections due to the np and eta{N} interactions in the final state.
Comparison between the calculations and data indicate sizable contributions
from the np and eta{N} final state interactions close to threshold.


title:
Relationship between Quark-Meson Coupling Model and Quantum
  Hadrodynamics

abstract:
  Using the quark-meson coupling (QMC) model, we study nuclear matter from the
point of view of quark degrees of freedom. Performing a re-definition of the
scalar field in matter, we transform QMC to a QHD-type model with a non-linear
scalar potential. The potentials obtained from QMC are compared with those of
the relativistic mean-field models.


title:
Exploration of Resonant Continuum and Giant Resonance in the
  Relativistic Approach

abstract:
  Single-particle resonant-states in the continuum are determined by solving
scattering states of the Dirac equation with proper asymptotic conditions in
the relativistic mean field theory (RMF). The regular and irregular solutions
of the Dirac equation at a large radius where the nuclear potentials vanish are
relativistic Coulomb wave functions, which are calculated numerically.
Energies, widths and wave functions of single-particle resonance states in the
continuum for ^{120}Sn are studied in the RMF with the parameter set of NL3.
The isoscalar giant octupole resonance of ^{120}Sn is investigated in a fully
consistent relativistic random phase approximation. Comparing the results with
including full continuum states and only those single-particle resonances we
find that the contributions from those resonant-states dominate in the nuclear
giant resonant processes.


title: Asymptotic Freedom for Non-Relativistic Confinement

abstract:
  Some aspects of asymptotic freedom are discussed in the context of a simple
two-particle non-relativisitic confining potential model. In this model
asymptotic freedom follows from the similarity of the free-particle and bound
state radial wave functions at small distances and for the same angular
momentum and the same large energy. This similarity, which can be understood
using simple quantum mechanical arguments, can be used to show that the exact
response function approaches that obtained when final state interactions are
ignored. A method of calculating corrections to this limit is given and
explicit examples are given for the case of the harmonic oscillator.


title: Deep inelastic scattering from light nuclei

abstract:
  We review recent developments in the study of deep inelastic scattering from
light nuclei, focusing in particular on deuterium, helium, and lithium.
Understanding the nuclear effects in these systems is essential for the
extraction of information on the neutron structure function.


title:
Single-particle potential in a chiral approach to nuclear matter
  including short range NN-terms

abstract:
  We extend a recent chiral approach to nuclear matter of Lutz et al. [Phys.
Lett. B474 (2000) 7] by calculating the underlying (complex-valued)
single-particle potential U(p,k_f) + i W(p,k_f). The potential for a nucleon at
the bottom of the Fermi-sea, U(0,k_{f0})= - 20.0 MeV, comes out as much too
weakly attractive in this approach. Even more seriously, the total
single-particle energy does not rise monotonically with the nucleon momentum p,
implying a negative effective nucleon mass at the Fermi-surface. Also, the
imaginary single-particle potential, W(0,k_{f0}) = 51.1 MeV, is too large. More
realistic single-particle properties together with a good nuclear matter
equation of state can be obtained if the short range contributions of
non-pionic origin are treated in mean-field approximation (i.e. if they are not
further iterated with 1pi-exchange). We also consider the equation of state of
pure neutron matter $bar E_n(k_n)$ and the asymmetry energy A(k_f) in that
approach. The downward bending of these quantities above nuclear matter
saturation density seems to be a generic feature of perturbative chiral
pion-nucleon dynamics.


title: The Lambda-Lambda Interaction and ^{6}_{Lambda Lambda}He

abstract:
  An OBE potential model for the ^{1}S_0 S = -2 interaction is analyzed with
emphasis on the role of coupling between the Lambda Lambda, N Xi, and Sigma
Sigma channels. Singlet scalar exchange, an approximation to two-pion exchange,
is significant in all channels; surprisingly, the one-pion exchange component
is almost negligible. The size of the channel coupling as a function of the
overall strength of the OBE model potential is examined. Implications of the
analysis for the binding energy of ^{6}_{Lambda Lambda}He are considered; the
new experimental datum may suggest a consistency between the extracted Lambda
Lambda matrix element and the relation implied by SU(3) among OBE baryon-baryon
interactions. \\


title: Improved Nearside-Farside Method for Elastic Scattering Amplitudes

abstract:
  A simple technique is described that provides an improved nearside-farside
(NF) method for elastic scattering amplitudes. The technique, involving the
novel resummation of a Legendre partial wave series, reduces the importance of
unphysical contributions to NF subamplitudes, which can arise in more
conventional NF decompositions. Detailed applications are made to a strong
absorption model and to a ^{16}O + ^{16}O optical potential at E_{lab} = 145
MeV. We also discuss ^{16}O + ^{16}O at E_{lab} = 480, 704, 1120 MeV, and alpha
+ ^{12}C, alpha + ^{40}Ca, both at E_{lab} = 1370 MeV.


title: Deformed Nuclei in a Chiral Model

abstract:
  We investigate the deformation properties of atomic nuclei in a hadronic
chiral SU_f(3) model approach. The parameters are fitted to hadron mass
properties and adjustments for spherical finite nuclei have been performed.
Using these parameters the deformation of a series of light and heavy nuclei
are obtained in a two-dimensional self-consistent calculation. In addition we
discuss a case of superdeformation in a heavy nucleus.


title: On the Surface Structure of Strange Superheavy Nuclei

abstract:
  Bound, strange, neutral superheavy nuclei, stable against strong decay, may
exist. A model effective field theory calculation of the surface energy and
density of such systems is carried out assuming vector meson couplings to
conserved currents and scalar couplings fit to data where it exists. The
non-linear relativistic mean field equations are solved assuming local baryon
sources. The approach is calibrated through a successful calculation of the
known nuclear surface tension.


title: Model Study of Three-Body Forces in the Three-Body Bound State

abstract:
  The Faddeev equations for the three-body bound state with two- and three-body
forces are solved directly as three-dimensional integral equation. The
numerical feasibility and stability of the algorithm, which does not employ
partial wave decomposition is demonstrated. The three-body binding energy and
the full wave function are calculated with Malfliet-Tjon-type two-body
potentials and scalar Fujita-Miyazawa type three-body forces. The influence of
the strength and range of the three-body force on the wave function, single
particle momentum distributions and the two-body correlation functions are
studied in detail. The extreme case of pure three-body forces is investigated
as well.