title: Microscopic formula for transport coefficients of causal hydrodynamics

abstract:
  The Green-Kubo-Nakano formula should be modified in relativistic
hydrodynamics because of the problem of acausality and the breaking of sum
rules. In this work, we propose a formula to calculate the transport
coefficients of causal hydrodynamics based on the projection operator method.
As concrete examples, we derive the expressions for the diffusion coefficient,
the shear viscosity coefficient, and corresponding relaxation times.


title:
Relativistic mean-field model with density-dependent meson-nucleon
  couplings

abstract:
  Within the relativistic mean-field approach, we extend the Miyazaki model,
where the NN$\sigma$ and NN$\omega$ interactions are modified to suppress the
couplings between positive- and negative-energy states of a nucleon in matter.
Assuming appropriate density-dependence of the meson-nucleon couplings, we
study nuclear matter and finite nuclei. The model can reproduce the observed
properties of $^{16}$O and $^{40}$Ca well. We also examine if the model is
natural.


title:
In-medium omega meson mass and quark condensate in a Nambu Jona-Lasinio
  model constrained by recent experimental data

abstract:
  We have determined the relation between the in-medium $\omega $ meson mass
and quark condensate in the framework of a Nambu Jona-Lasinio model constrained
by some recent experimental data on the meson properties in nuclei. In addition
to the usual four-quark interactions, we have included eight-quark terms in the
Lagrangian. The parameters of this model have been determined using the meson
properties in the vacuum as well as in the medium. More particularly, we have
constrained both the in-medium pion decay constant to the value measured in
experiments on deeply bound pionic atoms and the in-medium $\omega $ meson mass
to the experimental value obtained either by the TAPS collaboration or by the
E325 experiment at KEK. Our results are compared to several scaling laws and in
particular to that of Brown and Rho.


title:
Relating breakup and incomplete fusion of weakly-bound nuclei through a
  classical trajectory model with stochastic breakup

abstract:
  A classical dynamical model that treats break-up stochastically is presented
for low energy reactions of weakly-bound nuclei. The three-dimensional model
allows a consistent calculation of breakup, incomplete and complete fusion
cross sections. The model is assessed by comparing the breakup observables with
CDCC quantum mechanical predictions, which are found to be in reasonable
agreement. Through the model, it is demonstrated that the breakup probability
of the projectile as a function of its distance from the target is of primary
importance for understanding complete and incomplete fusion at energies near
the Coulomb barrier.


title:
The neutron/proton ratio of squeezed-out nucleons and the high density
  behavior of the nuclear symmetry energy

abstract:
  Within a transport model it is shown that the neutron/proton ratio of
squeezed-out nucleons perpendicular to the reaction plane, especially at high
transverse momenta, in heavy-ion reactions induced by high energy neutron-rich
nuclei can be a useful tool for studying the high density behavior of the
nuclear symmetry energy.


title:
Statistical hadronization model description for rapidity densities at
  RHIC

abstract:
  The rapidity densities in Au-Au collisions at center-of-mass energies 200 and
130 A GeV measured at Relativistic Heavy-Ion Collider by STAR and PHENIX
collaborations are analyzed within the statistical hadronization model at
chemical freeze-out. We find that the model can describe the experimental
rapidity densities well. The corresponding chemical freeze-out parameters are
determined and they are seen to be in agreement with what we expect from our
previous analyzes at lower beam energies at AGS and SPS.


title: Nuclear Giant Resonances and Linear Response

abstract:
  We search for nonlinear effects in nuclear giant resonances (GRs), in
particular the isovector dipole and the isoscalar quadrupole modes. To that
end, we employ a spectral analysis of time-dependent Hartree-Fock (TDHF)
dynamics using Skyrme forces. Based on TDHF calculations over a wide range of
excitation amplitudes, we explore the collectivity and degree of harmonic
motion in these modes. Both GR modes turn out to be highly harmonic in heavy
nuclei from A=100 on. There is no trace of a transition to irregular motion and
multiple resonances are predicted. Slight anharmonicities are seen for light
nuclei, particularly for $^{16}$O. These are mainly caused by the spin-orbit
splitting.


title: Monopole Excitation to Cluster States

abstract:
  We discuss strength of monopole excitation of the ground state to cluster
states in light nuclei. We clarify that the monopole excitation to cluster
states is in general strong as to be comparable with the single particle
strength and shares an appreciable portion of the sum rule value in spite of
large difference of the structure between the cluster state and the
shell-model-like ground state. We argue that the essential reasons of the large
strength are twofold. One is the fact that the clustering degree of freedom is
possessed even by simple shell model wave functions. The detailed feature of
this fact is described by the so-called Bayman-Bohr theorem which tells us that
SU(3) shell model wave function is equivalent to cluster model wave function.
The other is the ground state correlation induced by the activation of the
cluster degrees of freedom described by the Bayman-Bohr theorem. We
demonstrate, by deriving analytical expressions of monopole matrix elements,
that the order of magnitude of the monopole strength is governed by the first
reason, while the second reason plays a sufficient role in reproducing the data
up to the factor of magnitude of the monopole strength. Our explanation is made
by analysing three examples which are the monopole excitations to the $0^+_2$
and $0^+_3$ states in $^{16}$O and the one to the $0^+_2$ state in $^{12}$C.
The present results imply that the measurement of strong monopole transitions
or excitations is in general very useful for the study of cluster states.


title:
In-medium NN cross sections determined from stopping and collective flow
  in intermediate-energy heavy-ion collisions

abstract:
  In-medium nucleon-nucleon scattering cross sections are explored by comparing
results of quantum molecular dynamics simulations to data on stopping and on
elliptic and directed flow in intermediate-energy heavy-ion collisions. The
comparison points to in-medium cross sections which are suppressed at low
energies but not at higher energies. Positive correlations are found between
the degree of stopping and the magnitudes of elliptic and directed flows.


title:
Chiral bands for quasi-proton and quasi-neutron coupling with a triaxial
  rotor

abstract:
  A particle rotor model (PRM) with a quasi-proton and a quasi-neutron coupled
with a triaxial rotor is developed and applied to study chiral doublet bands
with configurations of a $h_{11/2}$ proton and a $h_{11/2}$ quasi-neutron. With
pairing treated by the BCS approximation, the present quasi-particle PRM is
aimed at simulating one proton and many neutron holes coupled with a triaxial
rotor. After a detailed analysis of the angular momentum orientations, energy
separation between the partner bands, and behavior of electromagnetic
transitions, for the first time we find aplanar rotation or equivalently chiral
geometry beyond the usual one proton and one neutron hole coupled with a
triaxial rotor.


title:
Partial Dynamical Symmetry at Critical-Points of Quantum Phase
  Transitions

abstract:
  We show that partial dynamical symmetries (PDS) can occur at critical-points
of quantum phase transitions, in which case, underlying competing symmetries
are conserved exactly by a subset of states, and mix strongly in other states.
Several types of PDS are demonstrated with the example of critical-point
Hamiltonians for first- and second-order transitions in the framework of the
interacting boson model, whose dynamical symmetries correspond to different
shape-phases in nuclei.


title: Viscosity of High Energy Nuclear Fluids

abstract:
  Relativistic high energy heavy ion collision cross sections have been
interpreted in terms of almost ideal liquid droplets of nuclear matter. The
experimental low viscosity of these nuclear fluids have been of considerable
recent quantum chromodynamic interest. The viscosity is here discussed in terms
of the string fragmentation models wherein the temperature dependence of the
nuclear fluid viscosity obeys the Vogel-Fulcher-Tammann law.


title: Hadronization revisited: the dynamics behind hadro-chemical equilibrium

abstract:
  The multiplicity of hadronic species created in elementary, and in
nucleus-nucleus collisions, are known to be well reproduced by the statistical
hadronization model, in its canonical and grand-canonical versions.To
understand the origin of the implied equilibrium we revisit the hadronization
models developed for e+e- annihilation to hadrons which imply spatial color
pre-confinement clusters forming at the end of the pQCD evolution, which decays
into on-shell hadrons/resonances. The classical ensemble description arises as
a consequence of decoherence and phase space dominance during cluster
formation, and decay.For A+A collisions we assume that hadronization occurs
from similar singlet clusters which will overlap spatially owing to the extreme
density. This is imaged in the transition to the grand-canonical ensemble.This
transition sets in with increasing A and collision centrality. It can be
described by a percolation model.


title:
Isospin mixing in the nucleon and 4He and the nucleon strange electric
  form factor

abstract:
  In order to isolate the contribution of the nucleon strange electric form
factor to the parity-violating asymmetry measured in 4He(\vec e,e')4He
experiments, it is crucial to have a reliable estimate of the magnitude of
isospin-symmetry-breaking (ISB) corrections in both the nucleon and 4He. We
examine this issue in the present letter. Isospin admixtures in the nucleon are
determined in chiral perturbation theory, while those in 4He are derived from
nuclear interactions, including explicit ISB terms. A careful analysis of the
model dependence in the resulting predictions for the nucleon and nuclear ISB
contributions to the asymmetry is carried out. We conclude that, at the low
momentum transfers of interest in recent measurements reported by the HAPPEX
collaboration at Jefferson Lab, these contributions are of comparable magnitude
to those associated with strangeness components in the nucleon electric form
factor.


title:
Multiplicity Fluctuations in Proton-Proton and Nucleus-Nucleus
  Collisions

abstract:
  We study the scaled variances of multiplicity fluctuations in nucleus-nucleus
collisions at SPS and RHIC energies within the HSD transport model. The HSD
results are compared with proton-proton data and with predictions of the
hadron-resonance gas statistical model. We find that the HSD scaled variances
$\omega_i$ for negatively, positively, and all charged hadrons in central
nucleus-nucleus collisions remain close to the $\omega_i$ values in
proton-proton collisions and increase with collision energy as the
corresponding multiplicities per participating nucleon. The statistical model
predicts very different behavior of $\omega_i$. However, a comparison with
preliminary NA49 data for the most central Pb+Pb collisions at SPS energies
does not permit to distinguish the HSD and statistical model results. New
measurements of the multiplicity fluctuations in nucleus-nucleus collisions in
a wide energy region with large acceptance are needed to allow for a proper
determination of the underlying dynamics.


title: Flavor content of nucleon form factors

abstract:
  The flavor content of nucleon form factors is analyzed using two different
theoretical approaches. The first is based on a phenomenological two-component
model in which the external photon couples to both an intrinsic three-quark
structure and a meson cloud via vector-meson dominance. The flavor content of
the nucleon form factors is extracted without introducing any additional
parameter. A comparison with recent data from parity-violating electron
scattering experiments shows a good overall agreement for the strange form
factors.
  A more microscopic approach is that of an unquenched quark model proposed by
Geiger and Isgur which is based on valence quark plus glue dominance to which
quark-antiquark pairs are added in perturbation. In the original version the
importance of $s \bar{s}$ loops in the proton was studied. Here we present the
formalism for a new generation of unquenched quark models which, among other
extensions, includes the contributions of $u \bar{u}$ and $d \bar{d}$ loops.
Finally, we discuss some preliminary results in the closure limit.


title: Hydrodynamic Flow and Jet Induced Mach Shocks at RHIC and LHC

abstract:
  We discuss the present collective flow signals for the phase transition to
quark-gluon plasma (QGP) and the collective flow as a barometer for the
equation of state (EoS). A study of Mach shocks induced by fast partonic jets
propagating through the QGP is given. We predict a significant deformation of
Mach shocks in central Au+Au collisions at RHIC and LHC energies as compared to
the case of jet propagation in a static medium. Results of a hydrodynamical
study of jet energy loss are presented.


title: B(E1) Strengths from Coulomb Excitation of 11Be

abstract:
  The $B$(E1;$1/2^+\to1/2^-$) strength for $^{11}$Be has been extracted from
intermediate energy Coulomb excitation measurements, over a range of beam
energies using a new reaction model, the extended continuum discretized coupled
channels (XCDCC) method. In addition, a measurement of the excitation cross
section for $^{11}$Be+$^{208}$Pb at 38.6 MeV/nucleon is reported. The $B$(E1)
strength of 0.105(12) e$^2$fm$^2$ derived from this measurement is consistent
with those made previously at 60 and 64 MeV/nucleon, i n contrast to an
anomalously low result obtained at 43 MeV/nucleon. By coupling a
multi-configuration description of the projectile structure with realistic
reaction theory, the XCDCC model provides for the first time a fully quantum
mechanical description of Coulomb excitation. The XCDCC calculations reveal
that the excitation process involves significant contributions from nuclear,
continuum, and higher-order effects. An analysis of the present and two earlier
intermediate energy measurements yields a combined B(E1) strength of 0.105(7)
e$^2$fm$^2$. This value is in good agreement with the value deduced
independently from the lifetime of the $1/2^-$ state in $^{11}$Be, and has a
comparable p recision.


title: Thermal Radiation from Heavy Ion Collisions at RHIC

abstract:
  The direct photon spectrum measured by the PHENIX collaboration in Au + Au
collisions at sqrt{s_{NN}}=200 GeV has been analyzed. It has been shown that
the data can be reproduced reasonably well by assuming a deconfined state of
thermalized quarks and gluons. The effects of the equation of state on the
value of the initial temperature have been studied. The modifications of
hadronic properties at non-zero temperature have been taken in to account.


title:
Fermion Systems with Fuzzy Symmetries (Leveraging the Known to
  Understand the Unknown)

abstract:
  Microscopic models, which embody the simplicity and significance of a
dynamical symmetry approach to nuclear structure, are reviewed. They can reveal
striking features of atomic nuclei when a symmetry dominates and solutions in
domains that may otherwise be unreachable.


title: Light Nuclei in the Framework of the Symplectic No-core Shell Model

abstract:
  A symplectic no-core shell model (Sp-NCSM) is constructed with the goal of
extending the {\it ab-initio} NCSM to include strongly deformed
higher-oscillator-shell configurations and to reach heavier nuclei that cannot
be studied currently because the spaces encountered are too large to handle,
even with the best of modern-day computers. This goal is achieved by
integrating two powerful concepts: the {\it ab-initio} NCSM with that of the
$\mathrm{Sp}(3,\mathbb{R})\supset\mathrm{SU}(3)$ group-theoretical approach.
The NCSM uses modern realistic nuclear interactions in model spaces that
consists of many-body configurations up to a given number of $\hbar\Omega$
excitations together with modern high-performance parallel computing
techniques. The symplectic theory extends this picture by recognizing that when
deformed configurations dominate, which they often do, the model space can be
better selected so less relevant low-lying $\hbar\Omega$ configurations yield
to more relevant high-lying $\hbar\Omega$ configurations, ones that respect a
near symplectic symmetry found in the Hamiltonian. Results from an application
of the Sp-NCSM to light nuclei are compared with those for the NCSM and with
experiment.


title: Symplectic Symmetry and the Ab Initio No-Core Shell Model

abstract:
  The symplectic symmetry of eigenstates for the $0^+_{gs}$ in $^{16}$O and the
$0^+_{gs}$ and lowest $2^+$ and $4^+$ configurations of $^{12}$C that are
well-converged within the framework of the no-core shell model with the JISP16
realistic interaction is examined. These states are found to project at the
85-90% level onto very few symplectic representations including the most
deformed configuration, which confirms the importance of a symplectic no-core
shell model and reaffirms the relevance of the Elliott $\mathrm{SU}(3)$ model
upon which the symplectic scheme is built.


title:
Exciting pions in nuclei: DCX and Electroproduction in the resonance
  region

abstract:
  We describe the double charge exchange (DCX) reaction of pions with different
nuclear targets at incident kinetic energies of 120-180 MeV within the GiBUU
transport framework. The DCX process is highly sensitive to details of the
interactions of pions with the nuclear medium and, therefore, represents a
major benchmark for any model of pion scattering off nuclei at low and
intermediate energies. We achieve a good quantitative agreement with the
extensive data set obtained at LAMPF. Furthermore, we present first results on
electron scattering off nuclei for beam energies of 700-1500 MeV and
virtualities of Q^2<700 MeV^2. Including quasi-elastic and pion- production
processes and employing in-medium kinematics and realistic form factors, we
evaluate inclusive cross sections and compare to data obtained at the ADONE
storage ring (Frascati).


title: Exact solution of the spin-isospin proton-neutron pairing Hamiltonian

abstract:
  The exact solution of proton-neutron isoscalar-isovector (T=0,1) pairing
Hamiltonian with non-degenerate single-particle orbits and equal pairing
strengths (g_{T=1}= g_{T=0}) is presented for the first time. The Hamiltonian
is a particular case of a family of integrable SO(8) Richardson-Gaudin (RG)
models. The exact solution of the T=0,1 pairing Hamiltonian is reduced to a
problem of 4 sets of coupled non linear equations that determine the spectral
parameters of the complete set of eigenstates. The microscopic structure of
individual eigenstates is analyzed in terms of evolution of the spectral
parameters in the complex plane for system of A=80 nucleons. The spectroscopic
trends of the exact solutions are discussed in terms of generalized rotations
in isospace.


title: Transition Matrix Elements for Pion Photoproduction

abstract:
  We have obtained the transition matrix elements for pion photoproduction by
considering the number of gamma matrices involved. The approach based on the
most general conditions of gauge invariance, current conservation and
transversality. The approach is fairly consistent with literatures.


title: Isospin mixing and energy distributions in three-body decay

abstract:
  The structure of the second 2$^+$ resonance in $^{6}$Li is investigated with
special emphasis on its isospin 0 components. The wave functions are computed
in a three-body model ($\alpha$+$n$+$p$) using the hyperspherical adiabatic
expansion method combined with complex scaling. In the decay into three free
particles the symmetry conserving short-range interaction dominates at short
distance whereas the symmetry breaking Coulomb interaction dominates at
intermediate and large distances resulting in substantial isospin mixing. We
predict the mixing and the energy distributions of the fragments after decay.
Computations are consistent with available experiments. We conjecture that
nuclear three-body decays frequently produce such large isospin mixing at large
distance where the energy distributions. are determined.


title: Nuclear Superfluidity and Cooling Time of Neutron-Star Crust

abstract:
  We analyse the effect of neutron superfluidity on the cooling time of inner
crust matter in neutron stars, in the case of a rapid cooling of the core. The
specific heat of the inner crust, which determines the thermal response of the
crust, is calculated in the framework of HFB approach at finite temperature.
The calculations are performed with two paring forces chosen to simulate the
pairing properties of uniform neutron matter corresponding respectively to
Gogny-BCS approximation and to many-body techniques including polarisation
effects. Using a simple model for the heat transport across the inner crust, it
is shown that the two pairing forces give very different values for the cooling
time.


title: Four-body calculation of proton-3He scattering

abstract:
  The four-body equations of Alt, Grassberger and Sandhas are solved, for the
first time, for proton-${}^3\mathrm{He}$ scattering including the Coulomb
interaction between the three protons using the method of screening and
renormalization as it was done recently for proton-deuteron scattering. Various
realistic two-nucleon potentials are used. Large Coulomb effects are seen on
all observables. Comparison with data at different energies shows large
deviations in the proton analyzing power but quite reasonable agreement in
other observables. The effect of nucleon-nucleon magnetic moment interaction
and correlations between $\pd$ and $\pHe$ analyzing powers are studied.


title: Ab initio four-body calculation of n-3He, p-3H, and d-d scattering

abstract:
  Four-body equations in momentum space are solved for neutron-$\He$,
proton-$\Hh$, and deuteron-deuteron scattering; all three reactions are
coupled. The Coulomb interaction between the protons is included using the
screening and renormalization approach as it was recently done for
proton-deuteron and proton-$\He$ scattering. Realistic interactions are used
between nucleon pairs. For the first time fully converged results for the
observables pertaining to the six different elastic and transfer reactions are
obtained and compared with experimental data.


title: Dynamical Symmetries Reflected in Realistic Interactions

abstract:
  Realistic nucleon-nucleon (NN) interactions, derived within the framework of
meson theory or more recently in terms of chiral effective field theory, yield
new possibilities for achieving a unified microscopic description of atomic
nuclei. Based on spectral distribution methods, a comparison of these
interactions to a most general Sp(4) dynamically symmetric interaction, which
previously we found to reproduce well that part of the interaction that is
responsible for shaping pairing-governed isobaric analog 0+ states, can
determine the extent to which this significantly simpler model Hamiltonian can
be used to obtain an approximate, yet very good description of low-lying
nuclear structure. And furthermore, one can apply this model in situations that
would otherwise be prohibitive because of the size of the model space. In
addition, we introduce a Sp(4) symmetry breaking term by including the
quadrupole-quadrupole interaction in the analysis and examining the capacity of
this extended model interaction to imitate realistic interactions. This
provides a further step towards gaining a better understanding of the
underlying foundation of realistic interactions and their ability to reproduce
striking features of nuclei such as strong pairing correlations or collective
rotational motion.


title:
Physical Significance of q Deformation and Many-Body Interactions in
  Nuclei

abstract:
  The quantum deformation concept is applied to a study of pairing correlations
in nuclei with mass 40<A<100. While the nondeformed limit of the theory
provides a reasonable overall description of certain nuclear properties and
fine structure effects, the results show that the q deformation plays a
significant role in understanding higher-order effects in the many-body
interaction.


title:
Rapidity dependence of the photon to pion production ratio in high
  energy collisions

abstract:
  We investigate rapidity dependence of the ratio of photon and pion production
cross sections in high energy proton (deuteron) - nucleus collisions at RHIC
and LHC. This ratio, and its rapidity dependence can be a sensitive probe of
high density QCD (Color Glass Condensate) dynamics and shed further light on
the role of saturation physics at RHIC and LHC.


title:
Nuclear reaction studies of unstable nuclei using relativistic mean
  field formalisms in conjunction with Glauber model

abstract:
  We study nuclear reaction cross-sections for stable and unstable projectiles
and targets within Glauber model, using densities obtained from various
relativistic mean field formalisms. The calculated cross-sections are compared
with the experimental data in some specific cases. We also evaluate the
differential scattering cross-sections at several incident energies, and
observe that the results found from various densities are similar at smaller
scattering angles, whereas a systematic deviation is noticed at large angles.
In general, these results agree fairly well with the experimental data.


title: Dynamical symmetry of isobaric analog 0+ states in medium mass nuclei

abstract:
  An algebraic sp(4) shell model is introduced to achieve a deeper
understanding and interpretation of the properties of pairing-governed 0+
states in medium mass atomic nuclei. The theory, which embodies the simplicity
of a dynamical symmetry approach to nuclear structure, is shown to reproduce
the excitation spectra and fine structure effects driven by proton-neutron
interactions and isovector pairing correlations across a broad range of nuclei.


title: Isospin symmetry breaking in an algebraic pairing Sp(4) model

abstract:
  An exactly solvable sp(4) algebraic approach extends beyond the traditional
isospin conserving nuclear interaction to bring forward effects of isospin
symmetry breaking and isospin mixing resulting from a two-body nuclear
interaction that includes proton-neutron (pn) and like-particle isovector
pairing correlations plus significant isoscalar pn interactions. The model
yields an estimate for the extent to which isobaric analog 0+ states in light
and medium mass nuclei may mix with one another and reveals possible, but still
extremely weak, non-analog beta-decay transitions.


title:
Chiral Perturbation Theory and the first moments of the Generalized
  Parton Distriputions in a Nucleon

abstract:
  We discuss the first moments of the parity-even Generalized Parton
Distributions (GPDs) in a nucleon, corresponding to six (generalized) vector
form factors. We evaluate these fundamental properties of baryon structure at
low energies, utilizing the methods of covariant Chiral Perturbation Theory in
the baryon sector (BChPT). Our analysis is performed at leading-one-loop order
in BChPT, predicting both the momentum and the quark-mass dependence for the
three (generalized) isovector and (generalized) isoscalar form factors, which
are currently under investigation in lattice QCD analyses of baryon structure.
We also study the limit of vanishing four-momentum transfer where the
GPD-moments reduce to the well known moments of Parton Distribution Functions
(PDFs). For the isovector moment <x>_{u-d} our BChPT calculation predicts a new
mechanism for chiral curvature, connecting the high values for this moment
typically found in lattice QCD studies for large quark masses with the smaller
value known from phenomenology. Likewise, we analyze the quark-mass dependence
of the isoscalar moments in the forward limit and extract the contribution of
quarks to the total spin of the nucleon. We close with a first glance at the
momentum dependence of the isoscalar C-form factor of the nucleon.


title:
Microscopic Description of Isospin Mixing Pairing Correlations in the
  Framework of an Algebraic Sp(4) Model

abstract:
  We explore isospin mixing beyond that due to the Coulomb interaction in the
framework of an exactly solvable microscopic sp(4) algebraic approach.
Specifically, we focus on the isospin non-conserving part of the pure nuclear
pairing interaction. The outcome of this study shows the significance of the
pairing charge dependence and its role in mixing isospin multiplets of
pairing-governed isobaric analog 0+ states in light and medium mass nuclei,
especially in nuclei with equal numbers of protons and neutrons. The model
reveals possible, but still extremely weak, non-analog beta-decay transitions
and estimates their relative strengths within a shell closure.


title:
Underlying symmetries of realistic interactions and the nuclear
  many-body problem

abstract:
  The present study brings forward important information, within the framework
of spectral distribution theory, about the types of forces that dominate three
realistic interactions, CD-Bonn, CDBonn+ 3terms and GXPF1, in nuclei and their
ability to account for many-particle effects such as the formation of
correlated nucleon pairs and enhanced quadrupole collective modes.
Like-particle and proton-neutron isovector pairing correlations are described
microscopically by a model interaction with Sp(4) dynamical symmetry, which is
extended to include an additional quadrupole-quadrupole interaction. The
analysis of the results for the 1f7/2 level shows that both CD-Bonn+3terms and
GXPF1 exhibit a well-developed pairing character compared to CD-Bonn, while the
latter appears to build up more (less) rotational isovector T = 1 (isoscalar T
= 0) collective features. Furthermore, the three realistic interactions are in
general found to correlate strongly with the pairing+quadrupole model
interaction, especially for the highest possible isospin group of states where
the model interaction can be used to provide a reasonable description of the
corresponding energy spectra.


title: Global Properties of fp-Shell Interactions in Many-nucleon Systems

abstract:
  Spectral distribution theory, which can be used to compare microscopic
interactions over a broad range of nuclei, is applied in an analysis of two
modern effective interactions based on the realistic CD-Bonn potential for
$0\hbar\Omega$ no-core shell model calculations in the fp shell, as well as in
a comparison of these with the realistic shell-model GXPF1 interaction. In
particular, we explore the ability of these interaction to account for the
development of isovector pairing correlations and collective rotational motion
in the fp shell. Our findings expose the similarities of these two-body
interactions, especially as this relates to their pairing and rotational
characteristics. Further, the GXPF1 interaction is used to determine the
strength parameter of a quadrupole term that can be used to augment an
isovector-pairing model interaction with Sp(4) dynamical symmetry, which in
turn is shown to yield reasonable agreement with the low-lying energy spectra
of $^{58}$Ni and $^{58}$Cu.


title: Phase transitions in isolated strongly interacting systems

abstract:
  Thermodynamical properties of the nuclear matter at sub-saturation densities
were investigated using a simple van der Waals-like equation of state with an
additional term representing the symmetry energy. First-order
isospin-asymmetric liquid-gas phase transition appears restricted to isolated
isospin-asymmetric systems while the symmetric systems will undergo
fragmentation decay resembling the second-order phase transition. The density
dependence of the symmetry energy scaling with the Fermi energy satisfactorily
describes the symmetry energy at sub-saturation nuclear densities. The
deconfinement-confinement phase transition from the quark-gluon plasma to the
confined quark matter appears in the isolated systems continuous in energy
density while discontinuous in quark density. A transitional state of the
confined quark matter has a negative pressure and after hadronization an
explosion scenario can take place which can offer explanation for the HBT
puzzle as a signature of the phase transition.


title:
Effect of chemical freeze out on identified particle spectra at 200AGeV
  Au-Au Collisions at RHIC using SPheRIO

abstract:
  We investigate the effect of chemical freeze-out on identified particle
spectra at 200AGeV Au-Au Collisions at RHIC, by utilizing a full
three-dimensional hydrodynamical calculation. The hydrodynamical code SPheRIO
we employed is based on the smoothed particle hydrodynamic algorithm. In order
to describe the spectra of strange hadrons, the code has been further improved
by explicitly incorporating the strangeness conservation and a chemical
freeze-out mechanism. In our model, strange hadrons such as Lambda, Xi, Omega
and phi undergo the chemical freeze-out immediately after the hadronization,
and their multiplicities are fixed thereafter. At a lower temperature the
thermal freeze-out takes place for all the particles. It is shown that the
present model provides a reasonably good description for the spectra of
identified particles, in particular, considerable improvement is observed for
those of strange hadrons.


title: Chemical Equilibration at the Hagedorn Temperature

abstract:
  One important question in relativistic heavy ion collisions is if hadrons,
specifically anti-hyperons, are in equilibrium before thermal freezeout because
strangeness enhancement has long been pointed to as a signature for Quark Gluon
Plasma. Because anti-baryons have long equilibration times in the hadron gas
phase it has been suggested that they are "born" into equilibrium. However,
Hagedorn states, massive resonances, which are thought to appear near the
critical temperature, contribute to fast chemical equilibration times for a
hadron gas by providing extra degrees of freedom. Here we use master equations
to describe the interplay between Hagedorn resonances, pions, and baryon
anti-baryon pairs as they equilibrate over time and observe if the baryons and
anti-baryons are fully equilibrated within the fireball.


title:
Ward-Takahashi identity, soft photon theorem and the magnetic moment of
  the $\Delta$ resonance

abstract:
  Starting from the Ward-Takahashi identity for the radiative $\pi N$
scattering amplitude a generalization of the soft photon theorem approach is
obtained for an arbitrary energy of an emitted photon. The external particle
radiation part of the $\pi N\to\gamma'\pi'N' $ amplitude is analytically
reduced to the double $\Delta$ exchange amplitude with the
$\Delta\to\gamma'\Delta'$ vertex function.
  We have shown, that the double $\Delta$ exchange amplitudes with internal
$\Delta$ radiation is connected by current conservation with the corresponding
part of the external particle radiation terms. Moreover according to the
current conservation the internal and external particle radiation terms with
the $\Delta-\gamma'\Delta'$ vertex have a opposite sign i.e. they must cancel
each other.
  Therefore we have a screening of the internal double $\Delta$ exchange
diagram with the $\Delta-\gamma' \Delta'$ vertex by the external particle
radiation. This enables us to obtain a model independent estimation of the
dipole magnetic moment of $\Delta^+$ and $\Delta^{++}$ resonances
$\mu_{\Delta}$ through the anomalous magnetic moment of the proton $\mu_p$ as
$\mu_{\Delta^+}={{M_{\Delta}}\over {m_p}} \mu_p$ and $\mu_{\Delta^{++}}={3\over
2}\mu_{\Delta^+}$ in agreement with the values obtained from the fit of the
experimental cross section of the $\pi^+ p\to\gamma'\pi^+ p$ reaction.


title: The one-particle momentum transfer in point-form spectator approximation

abstract:
  The one-particle momentum transfer operator is derived in point-form
spectator approximation for $NN$ system. General expression is applied to
elastic electron-deuteron scattering and to deuteron photodisintegration.


title:
Boost-invariant mean field approximation and the nuclear Landau-Zener
  effect

abstract:
  We investigate the relation between time-dependent Hartree-Fock (TDHF) states
and the adiabatic eigenstates by constructing a boost-invariant single-particle
Hamiltonian. The method is numerically realized within a full three-dimensional
TDHF which includes all the terms of the Skyrme energy functional and without
any symmetry restrictions. The study of a free translational motion of a
nucleus demonstrates the validity of the concept of boost-invariant and
adiabatic TDHF states. The interpretation is further corroborated by the test
case of fusion of $^{16}{\textrm O}$+$^{16}{\textrm O}$. As a first
application, we present a study of the nuclear Landau-Zener effect on a
collision of $^{4}{\textrm {He}}$+$^{16}{\textrm O}$.


title:
Beam energy dependence of Coulomb-nuclear interference in the breakup of
  11Be

abstract:
  Within the post-form distorted wave Born approximation wherein pure Coulomb,
pure nuclear and their interference terms are treated consistently in a single
setup we study the beam energy dependence of the Coulomb-nuclear interference
terms in the breakup of 11Be on a medium mass 44Ti target. Our results suggest
that the Coulomb-nuclear interference terms are dependent on the incident beam
energy and can be as big as that of the individual Coulomb or nuclear terms
depending on the angle and energy of the breakup fragments. We also calculate
the relative energy spectra and one-neutron removal cross sections in the
breakup of 11Be on a heavy 208Pb target at 69 MeV/nucleon for two different
angular ranges of the projectile center of the mass scattering angle and
compare them with recently available experimental data.


title:
Parity-Projected Shell Model Monte Carlo Level Densities for fp-shell
  Nuclei

abstract:
  We calculate parity-dependent level densities for the even-even isotopes
58,62,66 Fe and 58 Ni and the odd-A nuclei 59 Ni and 65 Fe using the Shell
Model Monte Carlo method. We perform these calculations in the complete fp-gds
shell-model space using a pairing+quadrupole residual interaction. We find
that, due to pairing of identical nucleons, the low-energy spectrum is
dominated by positive parity states. Although these pairs break at around the
same excitation energy in all nuclei, the energy dependence of the ratio of
negative-to-positive parity level densities depends strongly on the particular
nucleus of interest. We find equilibration of both parities at noticeably lower
excitation energies for the odd-A nuclei 59 Ni and 65 Fe than for the
neighboring even-even nuclei 58 Ni and 66 Fe.


title:
Coupled-channels effects in elastic scattering and near-barrier fusion
  induced by weakly bound nuclei and exotic halo nuclei

abstract:
  The influence on fusion of coupling to the breakup process is investigated
for reactions where at least one of the colliding nuclei has a sufficiently low
binding energy for breakup to become an important process. Elastic scattering,
excitation functions for sub-and near-barrier fusion cross sections, and
breakup yields are analyzed for $^{6,7}$Li+$^{59}$Co. Continuum-Discretized
Coupled-Channels (CDCC) calculations describe well the data at and above the
barrier. Elastic scattering with $^{6}$Li (as compared to $^{7}$Li) indicates
the significant role of breakup for weakly bound projectiles. A study of
$^{4,6}$He induced fusion reactions with a three-body CDCC method for the
$^6$He halo nucleus is presented. The relative importance of breakup and
bound-state structure effects on total fusion is discussed.


title: Predictions of Alpha Decay Half lives of Heavy and Superheavy Elements

abstract:
  Theoretical estimates for the lifetimes of several isotopes of heavy elements
with Z=102-120 are presented by calculating the quantum mechanical tunneling
probability in a WKB framework and using microscopic nucleus-nucleus potential
obtained by folding the densities of interacting nuclei with the DDM3Y
effective nuclear interaction. The $\alpha$-decay half lives calculated in this
formalism using the experimental $Q$-values are in good agreement over a wide
range of experimental data. Half lives are also calculated using $Q$-values
extracted from two mass formulae. The Viola-Seaborg-Sobiczewski (VSS) estimates
of $\alpha$-decay half lives with the same $Q$-values are presented for
comparison. The half life calculations are found to be quite sensitive to the
choice of $Q$-values. Comparison with the experimental data delineates the
inadequacies of older mass predictions in the domain of heavy and superheavy
elements as compared to the newer one by Muntian-Hofmann-Patyk-Sobiczewski, and
highlights necessity of a more accurate mass formula which can predict
$Q$-values with even higher precision.


title:
Nuclear forces with Delta-excitations up to next-to-next-to-leading
  order I: peripheral nucleon-nucleon waves

abstract:
  We study the two-nucleon force at next-to-next-to-leading order in a chiral
effective field theory with explicit Delta degrees of freedom. Fixing the
appearing low-energy constants from a next-to-leading order calculation of
pion-nucleon threshold parameters, we find an improved convergence of most
peripheral nucleon-nucleon phases compared to the theory with pions and
nucleons only. In the delta-full theory, the next-to-leading order corrections
are dominant in most partial waves considered.


title: Hybrid stars within a covariant, nonlocal chiral quark model

abstract:
  We present a hybrid equation of state (EoS) for dense matter in which a
nuclear matter phase is described within the Dirac-Brueckner-Hartree-Fock
(DBHF) approach and a two-flavor quark matter phase is modelled according to a
recently developed covariant, nonlocal chiral quark model. We show that modern
observational constraints for compact star masses (M ~ 2 M_sun) can be
satisfied when a small vector-like four quark interaction is taken into
account. The corresponding isospin symmetric EoS is consistent with flow data
analyses of heavy ion collisions and points to a deconfinement transition at
about 0.55 fm^-3.


title:
The three-nucleon system as a laboratory for nuclear physics: the need
  for 3N forces

abstract:
  Recent experimental results in three-body systems have unambiguously shown
that calculations based on nucleon-nucleon forces fail to accurately describe
many experimental observables and one needs to include effects which are beyond
the realm of the two-body potentials. This conclusion owes its significance to
the fact that experiments and calculations can both be performed with a high
accuracy. In this short review, a sample of recent experimental results along
with the results of the state-of-the-art calculations will be presented and
discussed.


title: The Friedrichs-Model with fermion-boson couplings

abstract:
  In this work we present an extended version of the Friedrichs Model, which
includes fermion-boson couplings. The set of fermion bound states is coupled to
a boson field with discrete and continuous components. As a result of the
coupling some of the fermion states may become resonant states. This feature
suggests the existence of a formal link between the occurrence of Gamow
Resonant States in the boson sector, as predicted by the standard Friedrichs
Model, with similar effects in the set of solutions of the fermion central
potential (Gamow fermion resonances). The structure of the solutions of the
model is discussed by using different approximations to the model space.
Realistic couplings constants are used to calculate fermion resonances in a
heavy mass nucleus.


title: The Friedrichs-Model with fermion-boson couplings II

abstract:
  In this work we present a formal solution of the extended version of the
Friedrichs Model. The Hamiltonian consists of discrete and continuum bosonic
states, which are coupled to fermions. The simultaneous treatment of the
couplings of the fermions with the discrete and continuous sectors of the
bosonic degrees of freedom leads to a system of coupled equations, whose
solutions are found by applying standard methods of representation of bound and
resonant states.


title:
Global microscopic calculations of ground-state spin and parity for
  odd-mass nuclei

abstract:
  Systematic calculations of ground-state spin and parity of odd-mass nuclei
have been performed within the Hartree--Fock--BCS (HFBCS) approach and the
Finite-Range Droplet Model for nuclei for which experimental data are
available. The unpaired nucleon has been treated perturbatively, and axial and
left-right reflection symmetries have been assumed. As for the HFBCS approach,
three different Skyrme forces have been used in the particle-hole channel,
whereas the particle-particle matrix elements have been approximated by a
seniority force. The calculations have been done for the 621 nuclei for which
the Nubase 2003 data set give assignments of spin and parity with strong
arguments. The agreement of both spin and parity in the self-consistent model
reaches about 80% for spherical nuclei, and about 40% for well-deformed nuclei
regardless of the Skyrme force used. As for the macroscopic-microscopic
approach, the agreement for spherical nuclei is about 90% and about 40% for
well-deformed nuclei, with different sets of spherical and deformed nuclei
found in each model.


title: Nuclear Saturation and Correlations

abstract:
  The relation between nuclear saturation and NN-correlations is examined.
Nucleons bound in a nucleus have a reduced effective mass due to the mean
field. This results in off-energy-shell scatterings modifying the free-space
NN-interaction by a dispersion correction. This is a major contribution to the
density-dependence of the effective in-medium force and to saturation.
Low-momentum effective interactions have been derived by renormalisation
methods whereby correlations may be reduced by effectively cutting off high
momentum components of the interaction. The effect of these cut-offs on
dispersive corrections and on saturation is the main focus of this paper. The
role of the tensor-force, its strength and its effect on correlations is of
particular interest. The importance of the definition of the mean field in
determining saturation as well as compressibility is also pointed out.
  With a cut-off below $\sim 2.6 fm^{-1}$ there is no saturation but at lower
density the binding energy is still well approximated suggesting that such a
force may be useful in nuclear structure calculations of (small) finite nuclei
if saturation is not an issue.
  A separable interaction that fits experimental phase-shifts exactly by
inverse scattering methods is used. Recent experiments measure short ranged
correlations (SRC's) to be 0.23 for $^{56}Fe$. Other experiments have obtained
a depletion of occupation-numbers in $^{208}Pb$ to be $\sim 0.2$. For nuclear
matter with the separable interaction and a continuous spectrum we obtain the
related quantity $\kappa$ to be 0.175 with the Bonn-B deuteron parameters,
while Machleidt's gets $\kappa= 0.125$ for the Bonn-B potential and a
continuous spectrum.


title: B- to light-meson transition form factors

abstract:
  We report a comprehensive set of results for B-meson heavy-to-light
transition form factors calculated using a truncation of, and expression for,
the transition amplitudes in which all elements are motivated by the study of
Dyson-Schwinger equations in QCD. In this relativistic approach, which realises
confinement and dynamical chiral symmetry breaking, all physical values of
momentum transfer in the transition form factors are simultaneously accessible.
Our results can be useful in the analysis and correlation of the large body of
data being accumulated at extant facilities, and thereby in probing the
Standard Model and beyond.


title:
Rapidity dependence of hadron production in central Au+Au collisions at
  $\sqrt{s_{NN}}= 200$ GeV

abstract:
  The rapidity and transverse momentum spectra for identified hadrons in
central Au+Au collisions at $\sqrt{s_{NN}}= 200$ GeV are computed in a quark
combination model. The data of rapidity distributions for $\pi^{\pm}$,
$K^{\pm}$, $p(\bar{p})$ and net protons $(p-\bar{p})$ are well described. We
also predict rapidity distributions for $K^{0}_{s}$, $\Lambda(\bar{\Lambda})$,
$\mathrm{\Xi^{-}}$ ($\mathrm{\bar{\Xi}^{_+}}$) and
$\mathrm{\Omega^{-}}+\mathrm{\bar{\Omega}}^{_+}$. The multiplicity ratios of
charged antihadrons to hadrons as a function of rapidity are reproduced. The
results for ${p}_{T}$ spectra of $\pi^{\pm}$, $K^{\pm}$, $p(\bar{p})$ and for
the $p/\pi$ ratios in a broader ${p}_{T}$ range agree well with the data.
Finally the rapidity dependence of transverse momentum distributions for
hadrons are given.


title: Nucleon resonances in \pi N scattering up to energies \sqrt(s) < 2.0 GeV

abstract:
  A meson-exchange model for pion-nucleon scattering was previously constructed
using a three-dimensional reduction scheme of the Bethe-Salpeter equation for a
model Lagrangian involving \pi, \eta, N, \Delta, \rho, and \sigma fields. We
thereby extend our previous work by including the \eta N channel and all the
\pi N resonances with masses ~ 2 GeV, up to the F waves. The effects of the
\pi\pi N channels are taken into account by introducing an effective width in
the resonance propagators. The extended model gives an excellent fit to both
\pi N phase shifts and inelasticity parameters in all channels up to the F
waves and for energies below 2 GeV. We present a new scheme to extract the
properties of overlapping resonances. The predicted values for the resonance
masses and widths as well as resonance pole positions and residues are compared
to the listing of the Particle Data Group.


title:
Determining neutron-capture cross sections via the surrogate reaction
  technique

abstract:
  Indirect methods play an important role in the determination of nuclear
reaction cross sections that are hard to measure directly. In this paper we
investigate the feasibility of using the so-called surrogate method to extract
neutron-capture cross sections for low energy compound-nuclear reactions in
spherical and near-spherical nuclei. We present the surrogate method and
develop a statistical nuclear-reaction simulation to explore different
approaches to utilize surrogate reaction data. We assess the success of each
approach by comparing the extracted cross sections with a predetermined
benchmark. In particular, we employ regional systematics of nuclear properties
in the 34 <= Z <= 46 region to calculate (n,gamma) cross sections for a series
of Zr isotopes, and to simulate a surrogate experiment and the extraction of
the desired cross section. We identify one particular approach that may provide
very useful estimates of the cross section, and we discuss some of the
limitations of the method. General recommendations for future (surrogate)
experiments are also given.


title: Overview of Antikaon-Nuclear Theory and Phenomenology

abstract:
  Experimental evidence for antikaon-nuclear quasibound states is briefly
reviewed. Theoretical and phenomenological arguments for and against deep
antikaon-nucleus potentials which might allow for narrow quasibound states are
reviewed, with recent calculations suggesting widths larger than 100 MeV for
binding energy smaller than 100 MeV. Results of RMF calculations that provide a
lower limit of 50+/-10 MeV for the width of deeply bound states are discussed.


title: Upper edge of the neutron star crust : the drip point and around

abstract:
  A semi-microscopic self-consistent quantum approach developed recently to
describe the inner crust structure of neutron stars within the Wigner-Seitz
method with the explicit inclusion of neutron and proton pairing correlations
is used for finding the neutron drip point which separates the outer and inner
crusts. The equilibrium configurations of the crust are examined in vicinity of
the drip point and in the upper part of the inner crust, for the density region
corresponding to average Fermi momenta $k_{\rm F}{=}0.2 \div 0.5 $fm$^{-1}$.


title: Finite amplitude method for the RPA solution

abstract:
  We propose a practical method to solve the random-phase approximation (RPA)
in the self-consistent Hartree-Fock (HF) and density-functional theory. The
method is based on numerical evaluation of the residual interactions utilizing
finite amplitude of single-particle wave functions. The method only requires
calculations of the single-particle Hamiltonian constructed with independent
bra and ket states. Using the present method, the RPA calculation becomes
possible with a little extension of a numerical code of the static HF
calculation. We demonstrate usefulness and accuracy of the present method
performing test calculations for isoscalar responses in deformed 20Ne.


title: Fission and Nuclear Liquid-Gas Phase Transition

abstract:
  The temperature dependence of the liquid-drop fission barrier is considered,
the critical temperature for the liquid-gas phase transition in nuclear matter
being a parameter. Experimental and calculated data on the fission probability
are compared for highly excited $^{188}$Os. The calculations have been made in
the framework of the statistical model. It is concluded that the critical
temperature for the nuclear liquid--gas phase transition is higher than 16 MeV.


title:
Ground-state properties of even-even N=Z nuclei within the
  Hartree-Fock-BCS and Higher Tamm-Dancoff approaches

abstract:
  We calculate the ground-state properties of well deformed, even-even N=Z
nuclei in the region between Ni-56 and Sn-100 within two different approaches,
focusing on the binding energy and deformation and pairing properties. First,
we employ the Hartree-Fock-BCS (HFBCS) approximation with the Skyrme effective
nucleon-nucleon interaction and discuss how the results depend on the
parameterization of the interaction and on the pairing force parameters
adjusted in various schemes to reproduce the experimental odd-even mass
differences. Then, within the Higher Tamm-Dancoff Approximation (HTDA), which
explicitly conserves the particle number, we calculate the same properties
starting from the HFBCS solutions. The HTDA treatment of the ground-state
correlations is converged within a n-particle-n-hole expansion using up to n=4
particle-hole excitations of the pair type (in the sense of Cooper pairs). We
compare the ground-state properties calculated in these two descriptions of
pairing correlations and deduce the importance of the particle-number
conservation in weak pairing regimes. Finally, we extend the HTDA calculations
so as to include the proton-neutron residual interaction and investigate the
role of proton-neutron pairing on the above ground-state properties.


title:
An alternative approach to the $\sigma$-meson-exchange in
  nucleon-nucleon interaction

abstract:
  Through a quantitative comparative study of the properties of deuteron and
nucleon-nucleon interaction with chiral quark model and quark delocalization
color screening model. We show that the $\sigma$-meson exchange used in the
chiral quark model can be replaced by quark delocalization and color screening
mechanism.


title:
An Interactive NeXTstep Interface to a Fortran Code for Solving Coupled
  Differential Equations

abstract:
  This paper describes a user-friendly frontend to a Fortran program that
integrates coupled nonlinear ordinary differential equations. The user
interface is built using the NeXTstep Interface Builder, together with a
public-domain graphical palette for displaying intermediate and final results.
In running the code for a given set of equation parameters the user sees a plot
of the solutions at each stage of the iterative process. In the case of a
successful sequence of iterations, the initially discontinuous curves smooth
out as the scale parameters of the solutions are adjusted to achieve a solution
to the nonlinear equations. If the iterative process goes astray, as it often
does for a poor choice of starting scale parameters, the user has the
opportunity to stop and start over with a better choice, guided by the result
of the previous run. The ease of interaction with the equations also allows the
user to develop an intuition regarding their solutions and to explore the
parameter space for the equations much more quickly.


title:
Quark Delocalization, Color Screening, and Nuclear Intermediate Range
  Attraction

abstract:
  We consider the effect of including quark delocalization and color screening,
in the nonrelativistic quark cluster model, on baryon-baryon potentials and
phase shifts. We find that the inclusion of these additional effects allows a
good qualitative description of both.


title:
Modelling the Off-Shell Dependence of $\pi^{o}- \eta$ Mixing with Quark
  Loops

abstract:
  It is shown that including form factors for the quark-pseudoscalar meson
couplings of the Georgi-Manohar chiral quark model allows one to obtain the
leading off-shell dependence of $\pi^{o}- \eta$ mixing (as predicted by chiral
perturbation theory) from the effect of quark loops on the meson propagators.
Implications for $\rho^{o} - \omega$ mixing and for the effects on meson mixing
contributions to few body charge symmetry breaking observables are also
discussed.


title: Quadrupole Contribution to Two Neutron Removal in Heavy Ion Collisions

abstract:
  In this report, electric quadrupole corrections to the two neutron removal
cross section measured in heavy ion collisions are estimated for $^{197}$Au and
$^{59}$Co targets. The quadrupole process is assumed to proceed primarily
through excitation of the giant isovector quadrupole resonance, which then
decays by neutron emission. For $^{59}$Co, the contribution from E2 radiation
is found to be small, while for $^{197}$Au we find the quadrupole contribution
resolves the discrepancy between experiment and the simple predictions of the
Weissacker-Williams virtual photon method.


title: Resonances in $\Lambda d$ Scattering and the $\Sigma$-hypertriton

abstract:
  Using separable $NN$ and $\Lambda N$-$\Sigma N$ potentials in the Faddeev
equations, we have demonstrated that the predicted enhancement in the $\Lambda
d$ cross section near the $\Sigma d$ threshold is associated with resonance
poles in the scattering amplitude. The positions of these poles, on the second
Riemann sheet of the complex energy plane, are determined by examining the
eigenvalues of the kernel of the Faddeev equations. This suggests that for a
certain class of $\Lambda N$-$\Sigma N$ potentials we can form a
$\Sigma$-hypertriton with a width of about 8 MeV.


title: Anatomy of the Soft-Photon Approximation in Hadron-Hadron Bremsstrahlung

abstract:
  A modified Low procedure for constructing soft-photon amplitudes has been
used to derive two general soft-photon amplitudes, a two-s-two-t special
amplitude $M^{TsTts}_{\mu}$ and a two-u-two-t special amplitude
$M^{TuTts}_{\mu}$, where s, t and u are the Mandelstam variables.
$M^{TsTts}_{\mu}$ depends only on the elastic T-matrix evaluated at four sets
of (s,t) fixed by the requirement that the amplitude be free of derivatives
($\partial$T/$\partial$s and /or $\partial$T/$\partial t$). Likewise
$M^{TuTts}_{\mu}$ depends only on the elastic T-matrix evaluated at four sets
of (u,t). In deriving these amplitudes, we impose the condition that
$M^{TsTts}_{\mu}$ and $M^{TuTts}_{\mu}$ reduce to $\bar{M}^{TsTts}_{\mu}$ and
$\bar{M}^{TuTts}_{\mu}$, respectively, their tree level approximations. The
amplitude $\bar{M}^{TsTts}_{\mu}$ represents photon emission from a sum of
one-particle t-channel exchange diagrams and one-particle s-channel exchange
diagrams, while the amplitude $\bar{M}^{TuTts} _{\mu}$ represents photon
emission from a sum of one-particle t-channel exchange diagrams and
one-particle u-channel exchange diagrams. The precise expressions for
$\bar{M}^{TsTts}_{\mu}$ and $\bar{M}^{TuTts}_{\mu}$ are determined by using the
radiation decomposition identities of Brodsky and Brown. We point out that it
is theoretically impossible to describe all bremsstrahlung processes by using
only a single class of soft-photon amplitudes. At least two different classes
are required: the amplitudes which depend on s and t or the amplitudes which
depend on u and t. When resonance effects are important, the amplitude
$M^{TsTts}_{\mu}$, not $M^{Low(st)}_{\mu}$, should be used. For processes with
strong u-channel exchange effects, the amplitude $M^{TuTts}_{\mu}$ should be
the first choice.


title:
Old Problems in Low-Energy $K N$ Physics and Perspectives Opening Up at
  New Machines

abstract:
  We survey the open problems in low--energy $KN$ physics, in the perspective
of using the new machines presently planned, such as the $\phi$--factory
DA$\Phi$NE at I.N.F.N. Nat. Labs. in Frascati (as a source of {\sl tagged},
low--energy kaons) and the KAON Factory at TRIUMF (as a producer of intense,
intermediate--energy kaon beams).


title: Low-Energy $KN$ Interactions at a $\phi$-Factory

abstract:
  The paper is the written version of a talk presented at the "VIIth Winter
School of Hadronic Physics", held in Folgaria (Trento), Italy, February 10--15,
1992.
  We intend to illustrate in this lecture the possibilities opening up at
machines planned for the nineties for low--energy kaon--nucleon interactions,
keeping the focus on the theoretical problems they should help to solve.
  We shall deal here only with the $\phi$--factory DA$\Phi$NE$^1$ and consider,
for brevity, interactions with light, gaseous targets, using gaseous $H_2$ as a
benchmark for which to estimate the rates to be expected in a typical
apparatus.


title: Low-Energy Kaon Interactions and Scattering on Nucleons and Light Nuclei

abstract:
  A chapter to be included in "The DA$\mit\Phi$NE Physics Handbook" by the
DA$\Phi$NE Theory Working Group, this paper covers the phenomenology of
low--energy $K N$ physics, with particular emphasis on the problems still to be
solved by a careful experimental investigation and on the theoretical tools to
analyse it.


title: Saturation in the Nuclear Matter Problem

abstract:
  Once density-dependent meson masses are introduced into the nuclear many-body
problem, conventional mechanisms for saturation no longer operate. We suggest
that a loop correction, essentially the introduction of the axial vector
coupling $g_A(\rho,k)$ as function of density $\rho$ and momentum $k$, can
bring about saturation, and present schematic calculations to illustrate this.
We find that a very small density-dependence in $g_A$ gives rise to a very
large saturating effect on nuclear matter. In fact, this new saturation
mechanism turns out to be more powerful than any of the conventional
mechanisms.


title: Relativistic Corrections to the Triton Binding Energy

abstract:
  The influence of relativity on the triton binding energy is investigated. The
relativistic three-dimensional version of the Bethe-Salpeter equation proposed
by Blankenbecler and Sugar (BbS) is used. Relativistic (non-separable)
one-boson-exchange potentials (constructed in the BbS framework) are employed
for the two-nucleon interaction. In a 34-channel Faddeev calculation, it is
found that relativistic effects increase the triton binding energy by about 0.2
MeV. Including charge-dependence (besides relativity), the final triton binding
energy predictions are 8.33 and 8.16 MeV for the Bonn A and B potential,
respectively.


title: Riemann's theorem for quantum tilted rotors

abstract:
  The angular momentum, angular velocity, Kelvin circulation, and vortex
velocity vectors of a quantum Riemann rotor are proven to be either (1) aligned
with a principal axis or (2) lie in a principal plane of the inertia ellipsoid.
In the second case, the ratios of the components of the Kelvin circulation to
the corresponding components of the angular momentum, and the ratios of the
components of the angular velocity to those of the vortex velocity are analytic
functions of the axes lengths.


title:
Effects of Octupole Vibrations on Quasiparticle Modes of Excitation in
  Superdeformed $^{193}$Hg

abstract:
  A particle-vibration coupling calculation based on the RPA and the cranked
shell model has been carried out for superdeformed rotational bands in
$^{193}$Hg. The result suggests that properties of single-particle motions in
superdeformed nuclei may be significantly affected by coupling effects with
low-frequency octupole vibrational modes, especially by the lowest $K=2$
octupole mode.


title: Monte Carlo methods for the nuclear shell model

abstract:
  We present novel Monte Carlo methods for treating the interacting shell model
that allow exact calculations much larger than those heretofore possible. The
two-body interaction is linearized by an auxiliary field; Monte Carlo
evaluation of the resulting functional integral gives ground-state or thermal
expectation values of few-body operators. The ``sign problem'' generic to
quantum Monte Carlo calculations is absent in a number of cases. We discuss the
favorable scaling of these methods with nucleon numb er and basis size and
their suitability to parallel computation.


title: Skyrmions and the Nuclear Force

abstract:
  The derivation of the nucleon-nucleon force from the Skyrme model is
reexamined. Starting from previous results for the potential energy of
quasistatic solutions, we show that a calculation using the Born-Oppenheimer
approximation properly taking into account the mixing of nucleon resonances,
leads to substantial central attraction. We obtain a potential that is in
qualitative agreement with phenomenological potentials. We also study the
non-adiabatic corrections, such as the velocity dependent transition
potentials, and discuss their importance.


title: Transverse response functions in the $\Delta$-resonance region

abstract:
  We calculate transverse response functions for quasi-elastic electron
scattering at high momentum transfers in a relativistic Hartree approximation
in configuration space. We treat the excitation of the $\Delta$ resonance using
its free mass and width. Good agreement with experiment is found in the dip
region.


title: Quartets of superdeformed bands and supersymmetry breaking

abstract:
  We examine the prediction of supersymmetric quantum mechanics that bands with
identical gamma-ray energies occur in quartets. The experimental data suggest
that this scenario is actually realized in nature. In the $A=150$ mass region,
four known pairs of isospectral bands can be grouped in two quartets, while
there are indications of such patterns around $A=190$. We introduce a small
supersymmetry breaking, necessary to describe the details of the data. We
derive relations among the transition rates that can be used to test our
predictions. pacs: 21.10.Re, 11.30.Pb, 21.60.Fw, 23.20.Lv


title: Electromagnetic Decays of Hyperons (II)

abstract:
  Excited negative parity hyperon masses are calculated in a chiral bag model
in which the pion and the kaon fields are treated as perturbations. We also
calculate the hadronic widths of $\lama$ and $\lamb$ as well as the coupling
constants of the lightest $I=0$ excited hyperon to the meson-baryon channels,
and discuss how the dispersive effects of the hadronic meson-baryon decay
channels affect the excited hyperon masses. Meson cloud corrections to the
electromagnetic decay widths of the two lightest excited hyperons into ground
states $\lamz$ and $\sigz$ are calculated within the same model and are found
to be small. Our results strengthen the argument that predictions of these
hyperon radiative decay widths provide an excellent test for various quark
models of hadrons.


title: Finite volume of baryons and the mass limit for neutron stars

abstract:
  We confirmed the following idea by numerical calculation: The extended
structure of baryons may make the nuclear equation of state stiffer at higher
density while keeping the compression modulus for normal nuclear matter around
its empirical value $K=240MeV$.The model built in this wayy fits all empirical
data for normal nuclear matter and gives the mass limit of neutron stars
compatible with the observation.


title: Coalescence, Percolation and Nuclear Multifragmentation

abstract:
  We show that the coalescence model for fragment formation leads to an
approximate site percolation model. Features characteristic of a percolation
model also appear in microscopic models of disassembly.


title: Pionic effects in deep inelastic scattering off nuclei

abstract:
  The structure functions calculated in the Chiral bag model reproduce quite
well, after appropriate perturbative evolution to large energy scales, the
experimental data. We use these results to interpret the structure of the $EMC$
data as a quenching of the pion decay constant due to the in medium behavior of
the nucleon. This explanation supports recent proposals of this phenomenon
whose origin is the scale invariance of the $QCD$ lagrangian.


title: Sum Rule Description of Color Transparency

abstract:
  The assumption that a small point-like configuration does not interact with
nucleons leads to a new set of sum rules that are interpreted as models of the
baryon-nucleon interaction. These models are rendered semi-realistic by
requiring consistency with data for cross section fluctuations in proton-proton
diffractive collisions.


title: Meson Mass Spectrum from Relativistic Equations in Configuration Space

abstract:
  A method is described for solving relativistic quasi-potential equations in
configuration space. The Blankenbecler-Sugar-Logunov-Tavkhelidze and an
equal-time equation, both relativistic covariant two-body equations containing
the full Dirac structure of positive and negative energy states, are studied in
detail. These equations are solved for a system of two constituent quarks
interacting through a potential consisting of a one-gluon exchange part with
running coupling constant plus a linear confining potential which is mostly
scalar and partly vector, and the spectrum of all light and heavy mesons is
calculated.


title:
Atomic Parity Nonconservation: Electroweak Parameters and Nuclear
  Structure

abstract:
  There have been suggestions to measure atomic parity nonconservation (PNC)
along an isotopic chain, by taking ratios of observables in order to cancel
complicated atomic structure effects. Precise atomic PNC measurements could
make a significant contribution to tests of the Standard Model at the level of
one loop radiative corrections. However, the results also depend upon certain
features of nuclear structure, such as the spatial distribution of neutrons in
the nucleus. To examine the sensitivity to nuclear structure, we consider the
case of Pb isotopes using various recent relativistic and non-relativistic
nuclear model calculations. Contributions from nucleon internal weak structure
are included, but found to be fairly negligible. The spread among present
models in predicted sizes of nuclear structure effects may preclude using Pb
isotope ratios to test the Standard Model at better than a one percent level,
unless there are adequate independent tests of the nuclear models by various
alternative strong and electroweak nuclear probes. On the other hand,
sufficiently accurate atomic PNC experiments would provide a unique method to
measure neutron distributions in heavy nuclei.


title:
Self-consistent anisotropic oscillator with cranked angular and vortex
  velocities

abstract:
  The Kelvin circulation is the kinematical Hermitian observable that measures
the true character of nuclear rotation. For the anisotropic oscillator, mean
field solutions with fixed angular momentum and Kelvin circulation are derived
in analytic form. The cranking Lagrange multipliers corresponding to the two
constraints are the angular and vortex velocities. Self-consistent solutions
are reported with a constraint to constant volume.


title:
$q^2$-Dependence of Meson Mixing in Few-Body Charge Symmetry Breaking:
  $\pi^o-\eta$ Mixing to One Loop in Chiral Perturbation Theory

abstract:
  It is pointed out that the meson mixing matrix elements usually considered
responsible for the bulk of the observed few-body charge symmetry breaking are
naturally $q^2$-dependent in QCD. For $\pi^o-\eta$ mixing, using the usual
representation of the pseudoscalar fields, the leading $q^2$ dependence can be
explicitly calculated using chiral perturbation theory to one loop, the result
being a significant decrease in the magnitude of the matrix element in going
from timelike to spacelike values of $q^2$. Since it is the latter range of
$q^2$ which is relevant to NN scattering and the few-body bound state, this
result calls into serious question the standard treatment of few-body charge
symmetry breaking contributions associated with $\pi^o-\eta$ and $\rho -\omega$
mixing.


title: On the pion-nucleon coupling constant

abstract:
  In view of persisting misunderstanding about the determination of the
pion-nucleon coupling constants in the Nijmegen multienergy partial-wave
analyses of pp, np, and pbar-p scattering data, we present additional
information which may clarify several points of discussion. We comment on
several recent papers addressing the issue of the pion-nucleon coupling
constant and criticizing the Nijmegen analyses.


title: Test of Scalar Meson Structure in $\phi$ Radiative Decays

abstract:
  We show that $\phi$ radiative decays into scalar mesons [$f_0$(975),
$a_0$(980)$\equiv S$] can provide important clues on the internal structures of
these mesons. Radiative decay widths vary widely: $B.R.=10^{-4}-10^{-6}$
depending on the substructures ($q\bar q$, $qq\bar q\bar q$, $K\bar K$,
glueball). Hence, we could discriminate among various models by measuring these
widths at future $\phi$ factories. The understanding of these meson structures
is valuable not only in hadron spectroscopy but also in nuclear physics in
connection with the widely-used but little-understood $\sigma$ meson. We also
find that the decay $\phi\rightarrow S\gamma \rightarrow K^0 \bar K^0\gamma$ is
not strong enough to pose a significant background problem for studying CP
violation via $\phi\rightarrow K^0 \bar K^0$ at the $\phi$ factories.


title: Hot Nuclear Matter : A Variational Approach

abstract:
  We develop a nonperturbative technique in field theory to study properties of
infinite nuclear matter at zero temperature as well as at finite temperatures.
Here we dress the nuclear matter with off-mass shell pions. The techniques of
thermofield dynamics are used for finite temperature calculations. Equation of
state is derived from the dynamics of the interacting system in a self
consistent manner. The transition temperature for nuclear matter appears to be
around 15 MeV.


title: Physics of the Quark-Gluon Plasma

abstract:
  Central nuclear collisions at energies far above 1 GeV/nucleon may provide
for conditions, where the transition from highly excited hadronic matter into
quark matter or quark-gluon plasma can be probed. Here I review our current
understanding of the physical properties of a quark-gluon plasma and review
ideas about the nature of, and signals for, the deconfinement transition. I
also give a detailed presentation of recent progress in the treatment of the
formation of a thermalized state at the parton level.


title: Magnetic Screening in Thermal Yang-Mills Theories

abstract:
  We develop a semiclassical method to calculate the density of magnetic
monopoles in non-abelian gauge theories at finite temperature in the dilute gas
approximation. This quantity is related to the inverse magnetic screening
length for which we obtain $\mu_M = 0.255 g^2T$ in SU(2).


title:
Relativistic Mean Field Calculations of $\Lambda $ and $\Sigma $
  Hypernuclei

abstract:
  Single--particle spectra of $\Lambda $ and $\Sigma $ hypernuclei are
calculated within a relativistic mean--field theory. The hyperon couplings used
are compatible with the $\Lambda $ binding in saturated nuclear matter,
neutron-star masses and experimental data on $\Lambda $ levels in hypernuclei.
Special attention is devoted to the spin-orbit potential for the hyperons and
the influence of the $\rho $-meson field (isospin dependent interaction).


title: Comparison of potential models with the pp scattering data below 350 MeV

abstract:
  We calculate the chi**2 of various NN potential models with respect to the pp
scattering data. We find that only the potential models which were explicitly
fitted to the pp data give a reasonable description of these data. Most models
give a pretty large chi**2 on the very low-energy pp data, due to incorrect 1S0
phase shifts.


title: The Nuclear Response in Delta-Isobar Region in the ($^3\!$He,t) Reaction

abstract:
  The excitation of a $\Delta$-isobar in a finite nucleus in charge--exchange
($^3\!$He,t) reaction is discussed in terms of a nuclear response function. The
medium effects modifying a $\Delta$- and a pion propagation were considered for
a finite size nucleus. The Glauber approach has been used for distortion of a
$^3\!$He and a triton in the initial and the final states. The effects
determining the peak positions and its width are discussed. Large displacement
width for the $\Delta$ - h excitations and considerable contribution of
coherent pion production were found for the reaction on $^{12}$C.


title: Exact 1-Fermion Loop Contributions in 1+1 Dimensional Solitons

abstract:
  We find solutions to the 1+1 dimensional scalar-only linear sigma model. A
new method is used to compute 1-fermion loop contributions exactly and
agreement with published results employing other methods is excellent. A
renormalization scheme which differs from that commonly used in such
calculations but similar to that required in 1+3 dimensions is also presented.
We compare ``kink'' {\it versus} ``shallow bag'' solutions paying careful
attention to the implications of the 1-fermion loop contributions for the
stability of the former. We find that, for small fermion multiplicities,
self-consistent shallow bag solutions are always more bound than their
metastable kink counterparts. However, as the fermion multiplicity increases,
shallow bags evolve into kinks which eventually are the only self-consistent
configurations. This situation is qualitatively the same for the two
renormalization schemes considered. When we construct ``baryons'', each
containing three fermions, the kink configuration is typically more bound than
the shallow bag when 1-fermion loop contributions are included.


title: Relativistic Nuclear Matter with Self-Consistent Correlation Energy

abstract:
  We study relativistic nuclear matter in the $\sigma - \omega$ model including
the ring-sum correlation energy. The model parameters are adjusted
self-consistently to give the canonical saturation density and binding energy
per nucleon with the ring energy included. Two models are considered,
mean-field-theory where we neglect vacuum effects, and the relativistic Hartree
approximation where such effects are included but in an approximate way. In
both cases we find self-consistent solutions and present equations of state. In
the mean-field case the ring energy completely dominates the attractive part of
the energy density and the elegant saturation mechanism of the standard
approach is lost, namely relativistic quenching of the scalar attraction. In
the relativistic Hartree approach the vacuum effects are included in an
approximate manner using vertex form factors with a cutoff of 1 - 2 GeV, the
range expected from QCD. Due to the cutoff, the ring energy for this case is
significantlysmaller, and we obtain self-consistent solutions which preserve
the basic saturation mechanism of the standard relativistic approach.


title:
The Lamda-N - Sigma-N Interaction with Isobar Coupling and Six-Quark
  Resonances

abstract:
  The long-range $\Lambda N-\Sigma N$ interaction is modeled by a configuration
space meson-exchange potential matrix coupling to channels with $\Delta$ and
$\Sigma(1385)$ isobars. An inner boundary condition, based on $R$-matrix
theory, replaces form factors for short-range effects and includes the effects
of free quark configurations. An excellent fit is obtained to the available
data, with only the energy-independent boundary conditions as free parameters.
The effect of isobar thresholds is shown to be substantial in several partial
waves and is crucial to the understanding of the higher energy $\Lambda N$
elastic scattering data.


title: Microscopic Origin of Quantum Chaos in Rotational Damping

abstract:
  The rotational spectrum of $^{168}$Yb is calculated diagonalizing different
effective interactions within the basis of unperturbed rotational bands
provided by the cranked shell model. A transition between order and chaos
taking place in the energy region between 1 and 2 MeV above the yrast line is
observed, associated with the onset of rotational damping. It can be related to
the higher multipole components of the force acting among the unperturbed
rotational bands.


title:
Poisson and Porter-Thomas Fluctuations in off-Yrast Rotational
  Transitions

abstract:
  Fluctuations associated with stretched E2 transitions from high spin levels
in nuclei around $^{168}$Yb are investigated by a cranked shell model extended
to include residual two-body interactions. It is found that the gamma-ray
energies behave like random variables and the energy spectra show the Poisson
fluctuation, in the cranked mean field model without the residual interaction.
With two-body residual interaction included, discrete transition pattern with
unmixed rotational bands is still valid up to around 600 keV above yrast, in
good agreement with experiments. At higher excitation energy, a gradual onset
of rotational damping emerges. At 1.8 MeV above yrast, complete damping is
observed with GOE type fluctuations for both energy levels and transition
strengths(Porter-Thomas fluctuations).


title: Hyperfine Populations Prior to Muon Capture

abstract:
  It is shown that the 1S level hyperfine populations prior to muon capture
will be statistical when either target or beam are unpolarised independent of
the atomic level at which the hyperfine interaction becomes appreciable. This
assertion holds in the absence of magnetic transitions during the cascade and
is true because of minimal polarisation after atomic capture and selective
feeding during the cascade.


title:
Kaon-Nucleon Scattering Amplitudes and Z$^*$-Enhancements from Quark
  Born Diagrams

abstract:
  We derive closed form kaon-nucleon scattering amplitudes using the ``quark
Born diagram" formalism, which describes the scattering as a single interaction
(here the OGE spin-spin term) followed by quark line rearrangement. The low
energy I=0 and I=1 S-wave KN phase shifts are in reasonably good agreement with
experiment given conventional quark model parameters. For $k_{lab}> 0.7$ Gev
however the I=1 elastic phase shift is larger than predicted by Gaussian
wavefunctions, and we suggest possible reasons for this discrepancy. Equivalent
low energy KN potentials for S-wave scattering are also derived. Finally we
consider OGE forces in the related channels K$\Delta$, K$^*$N and K$^*\Delta$,
and determine which have attractive interactions and might therefore exhibit
strong threshold enhancements or ``Z$^*$-molecule" meson-baryon bound states.
We find that the minimum-spin, minimum-isospin channels and two additional
K$^*\Delta$ channels are most conducive to the formation of bound states.
Related interesting topics for future experimental and theoretical studies of
KN interactions are also discussed.


title: Cross Section Fluctuations and Chaoticity in Heavy-Ion Dynamics

abstract:
  Cross section fluctuations in nuclear scattering are briefly reviewed in
order to show the main important features. Then chaotic scattering is
introduced by means of a very simple model. It is shown that chaoticity
produces the same kind of irregular fluctuations observed in light heavy--ion
collisions. The transition from order to chaos allows a new general framework
for a deeper understanding of reaction mechanisms.


title:
Chiral colour-dielectric model with perturbative quantum pions and
  gluons

abstract:
  Pionic contributions to static nucleon properties are calculated in a chiral
extension of the colour-dielectric model. The pion field and residual gluon
field are treated perturbatively. It is shown that with a simple choice for the
energy of the scalar confining field and in the chiral limit, the system of
equations describing the bare soliton and the perturbative pion and gluon
fields may be cast in a dimensionless, parameter free form for large glueball
mass. This enables a formula for the masses of the nucleon and delta including
leading order pionic and gluonic contributions and corrections for spurious
centre-of-mass motion, valid for a wide range of input parameters determining
the bare soliton solutions, to be derived. A further consequence of the scaling
behaviour is that pionic contributions to nucleon properties, calculated using
the methods of the cloudy bag model, are insensitive to the soliton parameters,
once the size of the soliton is fixed. The model results are very similar to
those of the cloudy bag model but the predicted masses are about 20\% too
large, and the pionic contributions to charge radii are underestimated.


title: Colour Transparency in Hadronic Basis

abstract:
  The dynamics of nuclear transparency in hard nuclear reactions is studied by
an expansion of the correlator of the hard scattering operator on a hadronic
basis. Colour transparency appears as an effect of interference between the
amplitudes corresponding to the final state interaction of different
intermediate baryonic states. We find that colour transparency occurs even at
moderate momentum transfers if one chooses the missing momentum of the struck
nucleon by appropriate kinematics. In general, the role of the Fermi-motion is
found to be crucial; without it, any effect of anomalous nuclear transparency
would be impossible.


title: High-energy pion-nucleus elastic scattering

abstract:
  We investigate theoretical approaches to pion--nucleus elastic scattering at
high energies (300 $\le T_\pi \le$ 1 GeV). A ``model--exact'' calculation of
the lowest--order microscopic optical model, carried out in momentum space and
including the full Fermi averaging integration, a realistic off--shell
pion--nucleon scattering amplitude and fully covariant kinematics, is used to
calibrate a much simpler theory. The simpler theory utilizes a local optical
potential with an eikonal propagator and includes the Coulomb interaction and
the first Wallace correction, both of which are found to be important.
Comparisons of differential cross sections out to beyond the second minimum are
made for light and heavy nuclei. Particularly for nuclei as heavy as $^{40}$Ca,
the eikonal theory is found to be an excellent approximation to the full
theory. (8 Figures available from authors)


title: Microscopic approach to pion-nucleus dynamics

abstract:
  Elastic scattering of pions from finite nuclei is investigated utilizing a
contemporary, momentum--space first--order optical potential combined with
microscopic estimates of second--order corrections. The calculation of the
first--order potential includes:\ \ (1)~full Fermi--averaging integration
including both the delta propagation and the intrinsic nonlocalities in the
$\pi$-$N$ amplitude, (2)~fully covariant kinematics, (3)~use of invariant
amplitudes which do not contain kinematic singularities, and (4)~a
finite--range off--shell pion--nucleon model which contains the nucleon pole
term. The effect of the delta--nucleus interaction is included via the mean
spectral--energy approximation. It is demonstrated that this produces a
convergent perturbation theory in which the Pauli corrections (here treated as
a second--order term) cancel remarkably against the pion true absorption terms.
Parameter--free results, including the delta--nucleus shell--model potential,
Pauli corrections, pion true absorption, and short--range correlations are
presented. (2 figures available from authors)


title: Dynamics of antibaryon-baryon annihilation in the Skyrme model

abstract:
  We examine the dynamics of a baryon number zero lump in the Skyrme picture,
as a model for annihilation in the $\bar{N}N$ system. We find that radiation
propagates at the causal limit as a localized pulse and that the linearized
theory gives a good approximation. Both of these results are contrary to
findings in the Sine-Gordon model.


title:
Chaotic Behavior in Warm Deformed Nuclei Induced by Residual Two-Body
  Interactions

abstract:
  Band mixing calculations in rapidly rotating well-deformed nuclei are
presented, investigating the properties of energy levels and rotational
transitions as a function of excitation energy. Substantial fragmentation of E2
transitions is found for $E_x \gsim$ 800 keV above yrast, which represents the
onset of rotational damping. Above $E_x \approx $ 2 MeV, energy levels and E2
strengths display fluctuations typical of quantum chaotic systems, which are
determined by the high multipole components of the two-body residual
interaction.


title: Electromagnetic Dissociation of Nuclei in Heavy-Ion Collisions

abstract:
  Large discrepancies have been observed between measured Electromagnetic
Dissociation(ED) cross sections and the predictions of the semiclassical
Weiz\"acker-Williams-Fermi(WWF) method. In this paper, the validity of the
semiclassical approximation is examined. The total cross section for
electromagnetic excitation of a nuclear target by a spinless projectile is
calculated in first Born approximation, neglecting recoil. The final result is
expressed in terms of correlation functions and convoluted densities in
configuration space. The result agrees with the WWF approximation to leading
order(unretarded electric dipole approximation), but the method allows an
analytic evaluation of the cutoff, which is determined by the details of the
electric dipole transition charge density. Using the Goldhaber-Teller model of
that density, and uniform charge densities for both projectile and target, the
cutoff is determined for the total cross section in the nonrelativistic limit,
and found to be smaller than values currently used for ED calculations. In
addition, cross sections are calculated using a phenomenological momentum space
cutoff designed to model final state interactions. For moderate projectile
energies, the calculated ED cross section is found to be smaller than the
semiclassical result, in qualitative agreement with experiment.


title:
Effect due to compositeness of nucleons in deep inelastic lepton nucleus
  scattering

abstract:
  The off-shell behaviors of bound nucleons in deep inelastic lepton nucleus
scattering are discussed in two scenarios with the basic constituents chosen to
be baryon-mesons and quark-gluons respectively in light-cone formalism. It is
found that when taking into account the effect due to internal quark structure
of nucleons, the derived scaling variable for bound nucleons and the calculated
nuclear structure functions are different from those in considering the
baryon-mesons as the effective elementary constituents. This implies that the
pure baryon-meson descriptions of nuclei give the inaccurate off-shell behavior
of the bound nucleon structure function, thereby the quark-gluons seem to be
the most appropriate degrees of freedom for nuclear descriptions. It is also
shown that the EMC effect cannot be explained by nuclear binding effect from a
sound theoretical basis.


title:
The Momentum Dependence of the $\rho-\omega$ Mixing Amplitude in a
  Hadronic Model

abstract:
  We calculate the momentum dependence of the $\rho-\omega$ mixing amplitude in
a purely hadronic model. The basic assumption of the model is that the mixing
amplitude is generated by $N{\bar{N}}$ loops and thus driven entirely by the
neutron-proton mass difference. The value of the amplitude at the
$\omega$-meson point is expressed in terms of only the $NN\omega$ and the
$NN\rho$ coupling constants. Using values for these couplings constrained by
empirical two-nucleon data we obtain a value for the mixing amplitude in
agreement with experiment. Extending these results to the spacelike region, we
find a $\rho-\omega$ contribution to the NN interaction that is strongly
suppressed and opposite in sign relative to the conventional contribution
obtained from using the constant on-shell value for the mixing amplitude.


title: Neutron matter - Quark matter phase transition and Quark star

abstract:
  We consider the neutron matter quark matter phase transition along with
possible existence of hybrid quark stars. The equation of state for neutron
matter is obtained using a nonperturbative method with pion dressing of the
neutron matter and an analysis similar to that of symmetric nuclear matter. The
quark matter sector is treated perturbatively in the small distance domain. For
bag constant $B^{1/4}$=148 MeV, a first order phase transition is seen. In the
context of neutron quark hybrid stars, Tolman-Oppenheimer-Volkoff equations are
solved using the equations of state for quark matter and for neutron matter
with a phase transition as noted earlier. Stable solutions for such stars are
obtained with the Chandrasekhar limit as 1.58 $M_\odot$ and radius around 10
km. The bulk of the star is quark matter with a thin crust of neutron matter of
less than a kilometer.


title: Pion interaction with the trinucleon up to the eta production threshold

abstract:
  Pion elastic, charge exchange scattering and induced eta production on the
trinucleon systems are investigated in a coupled-channels approach in momentum
space with Fadeev wave functions. The channel $\pi N \rightarrow \eta N$ is
included using an isobar model with S-, P-, and D-wave resonances. While the
coherent reactions like $^3$He($\pi,\pi)^3$He can be reasonably well reproduced
up to $T_{\pi}$=500 MeV, large discrepancies appear for the incoherent
processes, $^3$He($\pi^-,\pi^0)^3$H and $^3$He($\pi^-,\eta)^3$H at backward
angles and energies above $\Delta$-resonance. In the forward direction the
$(\pi,\eta)$ calculations underestimate the experimental measurements very
close to threshold but agreement with the data improves with increasing pion
energy. Predictions are made for the asymmetries of the various reactions on
polarized $^3$He.


title:
Revealing Intermittency in Nuclear Multifragmentation with 4$\PI$
  Detectors

abstract:
  The distortion on the intermittency signal, due to detection efficiency and
to the presence of pre--equilibrium emitted particles, is studied in a
schematic model of nuclear multi- fragmentation. The source of the
intermittency signal is modeled with a percolating system. The efficiency is
schematized by a simple function of the fragment size, and the presence of
pre--equilibrium particles is simulated by an additional non--critical fragment
source. No selection on the events is considered, and therefore all events are
used to calculate the moments. It is found that, despite the absence of event
selection, the intermittency signal is quite resistant to the distortion due to
the apparatus efficiency, while the inclusion of pre--equilibrium particles in
the moment calculation can substantially reduce the strength of the signal.
Pre--equilibrium particles should be therefore carefully separated from the
rest of the detected fragments, before the intermittency analysis on
experimental charge or mass distributions is carried out.


title: Near-Threshold Production of $\eta$-Mesons

abstract:
  It is shown that the striking energy variation in the $p\, d \rightarrow
\mbox{$^{\, 3}{\rm He}$}\, \eta$ cross section near threshold is probably due
to a final state interaction associated with a large (complex) $\eta
-\mbox{$^{3}{\rm He}$}$ scattering length. The consequences of this hypothesis
are studied for the production of the meson in the $\eta -\mbox{$^{4}{\rm
He}$}$ and $\eta -\mbox{$^{7}{\rm Be}$}$ channels.


title: A Quark Model of Antilambda-Lambda Production in Pbar-P Interactions

abstract:
  A quark model which includes both scalar and vector contributions to the
reaction mechanism is used in a DWBA calculation of total and differential
cross-sections, polarizations, and spin correlation coefficients for the
reaction $\bar p p \rightarrow \bar \Lambda \Lambda$ at laboratory momenta from
threshold to 1.92 GeV/c. The free parameters of the calculation include the
scalar and vector strengths, a quark cluster size parameter, and six parameters
in the unknown $\bar \Lambda \Lambda$ interaction. Excellent agreement with
experiment is found for a constructive interference of scalar and vector terms,
and for a $\bar \Lambda \Lambda$ potential which differs from that suggested by
several authors on the basis of SU(3) arguments. The fit to the data is better
than that obtained by other quark models, which use only scalar or vector
annihilation terms. The agreement with experiment is as good as that found in
meson-exchange models, which use more parameters than the present calculation.


title: Correlation measurements in high-multiplicity events

abstract:
  Requirements for correlation measurements in high--multiplicity events are
discussed. Attention is focussed on detection of so--called hot spots,
two--particle rapidity correlations, two--particle momentum correlations (for
quantum interferometry) and higher--order correlations. The signal--to--noise
ratio may become large in the high--multiplicity limit, allowing meaningful
single--event measurements, only if the correlations are due to collective
behavior.


title:
Chemical equilibration of $\pi$, $\rho$ and $\omega$ mesons in
  ultra--relativistic nuclear collisions

abstract:
  I estimate the degree of local chemical equilibration for $\pi$, $\rho$ and
$\omega$ mesons in ultra--relativistic nuclear collisions. The $\pi$ and $\rho$
mesons remain near chemical equilibrium in all cases, while the $\omega$ meson
density is typically 30--50\% higher than the equilibrium value for O+Ag
collisions at $\sqrt{s}=20$ GeV. If chemical reactions are turned off, the
$\omega$ meson density is much larger, 2.5--3 times its equilibrium value.
Thus, $\omega$ mesons may provide the most sensitive tests for the degree of
chemical equilibration in nuclear collisions.


title: Analysis techniques for high-multiplicity collisions

abstract:
  I discuss methods for identifying and quantifying phase transitions in
particle collisions, concentrating on two techniques for use in
ultra-relativistic nuclear collisions. The first technique is to use rapidity
correlation measurements to determine the correlation length, while the second
is to use the transverse mass distribution of dileptons in the rho-omega peak
to determine the transition temperature.