Asymmetry dependent potentials, which produce neutron skins, are utilized in the Boltzmann-Uehling-Uhlenbeck equation in order to simulate intermediate energy heavy-ion collisions. Compared to calculations done with the commonly used equation of states, the calculations which use the asymmetry dependent potentials produce neutron rich neck regions which reduces the orbiting of the major fragments and can produce primary, neutron rich, intermediate velocity (‘‘neck’’) fragments.

The mechanism of the Coulomb breakup reaction of the projectile nuclei with neutron halo structure is investigated by the time-dependent Schrödinger equation in three-dimensional space. The time evolution of the internal wave function between the core nucleus and the halo neutron is calculated in the target Coulomb field treated as the time-dependent external field. Calculations are done for the ${}_{}{}^{11}{}_{}{}^{}\mathrm{Be}$${+}^{208}$Pb system for which an experiment has been done recently. The calculated results support the picture of free-particle breakup mechanism: Only the core nucleus is affected by the target Coulomb field, while the halo neutron moves independently. As a result, we obtain large transverse and small longitudinal difference in the relative velocity between the core and the neutron after the breakup. The origin of the longitudinal velocity difference observed experimentally is left unresolved in our approach.

Interacting-boson approximation calculations of the properties of the lowest K=0 intrinsic excitation of deformed nuclei suggest that this mode is not a β vibration as is traditionally thought but rather it is a collective phonon built on the γ vibration. This conclusion is in agreement with a wide body of experimental data concerning the K=0 excitation.

Calculations are presented for the exclusive pion radiative capture reaction from complex nuclei A(π,γN)B in the framework of the nonlocal distorted wave impulse approximation. Our results are found to be in reasonable agreement with a recent TRIUMF experiment ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${\mathrm{\pi }}^{+}$,γp${)}^{15}$O. Since pion radiative capture is related to pion photoproduction via time reversal invariance, the findings reported here are at variance with the recent BATES experiment ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(γ,${\mathrm{\pi }}^{\mathrm{-}}$p${)}^{15}$O.

We calculate the equation of state of asymmetric nuclear matter in generalized chemical equilibrium in the relativistic Brueckner-Hartree-Fock approximation, and study its impact on the properties of (rapidly) rotating neutron stars by solving the stellar structure equations in the framework of general relativity theory.

Pauli-projected random Gaussians are used as a representation to solve the shell model equations. The elements of the representation are chosen by a variational procedure. This scheme is particularly suited to describe cluster formation and cluster decay in nuclei. It overcomes the basis-size problem of the ordinary shell model and the technical difficulties of the cluster-configuration shell model. The model reproduces the α-decay width of ${}_{}{}^{212}{}_{}{}^{}\mathrm{Po}$ satisfactorily.

The spectral function, measured in A(e,${\mathit{e}}^{\mathcal{’}}$p) reactions, is distorted by the final-state interaction of the struck proton with the residual nucleus. This causes a broadening of the observed transverse-momentum distribution which is large even in the ${}_{}{}^2{}_{}{}^{}\mathrm{H}$(e,${\mathit{e}}^{\mathcal{’}}$p) reaction. We discuss the effects of this ${\mathit{p}}_{\mathrm{\perp }}$broadening on the nuclear transparency measured in the recent NE18 experiment. Within conventional Glauber theory we can describe the measurements. Color transparency effects are thus small in agreement with our earlier predictions.

Fragments with 4≤Z≤15 have been studied from the reaction 486, 550, 640, and 730 MeV ${}_{}{}^{86}{}_{}{}^{}\mathrm{Kr}$${+}^{63}$Cu. A standard analysis procedure has been used to characterize the associated asymmetric fission barriers and compare them to the Sierk model (Yukawa plus exponential finite range nuclear potential). The predicted YEFRN model barriers are too small by ≊37%, a result that is in contrast with other studies. The often used statistical model code gemeni also fails to account for these excitation functions.

We examine the production of J/ψ mesons in high energy hadron-nucleus collisions using models that account for both the initial state modification of parton distributions in nuclei and the final state interaction of the produced cc¯ pairs. We show that, at the energies of current fixed target experiments, J/ψ production through quark-antiquark annihilation gives the largest contribution at ${\mathit{x}}_{\mathit{F}}$>0.5 while gluon-gluon fusion dominates the production at smaller ${\mathit{x}}_{\mathit{F}}$. The observed J/ψ suppression at large ${\mathit{x}}_{\mathit{F}}$ is directly connected to nuclear shadowing in deeply inelastic scattering. We find that a 6–8 mb cc¯-nucleon cross section is needed to explain the data on J/ψ suppression if a simple incoherent multiple scattering formalism is used for the final state interactions. We then provide a more complete model to incorporate the effects of final state multiple soft scatterings. With only one parameter, this model can fit both the normalization and A dependence of the data for a variety of nuclei.

The AGS spectrometer experiment E-802 has measured transverse mass spectra for charged hadrons over a wide rapidity interval in Si+Au, Si+Cu, and Si+Al reactions at 14.6A Gev/c. These results are compared for two different trigger conditions: central collisions corresponding to 7% of the inelastic cross section selected on multiplicity of charged particles and peripheral collisions corresponding to roughly 50% of the inelastic cross section selected on high kinetic energy at zero degrees. The invariant spectra are well described by exponentials in transverse mass allowing the extraction of rapidity distributions and inverse slope parameters for each specie emitted in the different reactions.

We have studied one and two-dimensional scaled factorial moments in ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$+S and ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$+Au collisions at 200 GeV/nucleon in a high statistics electronic measurement at the CERN SPS using pad-readout streamer tubes. We observe no intermittency signal beyond that produced by folding the fritiof event generator with a detailed model of our detector. The systematic effects of detector response, two-track separation, and finite statistics in a factorial moment analysis are discussed in detail. Even though the observed signal contains measurable distortions due to these experimental effects, we show that we are sensitive to intermittency. As an alternative method, a two-particle correlation function analysis was applied to the same data to measure correlated particle production at small scales. We show that this method does not suffer as much as the factorial moment analysis does from distortions due to the limited two-track resolution of the detector. The correlation functions also agree with the predictions of fritiof filtered through our detector simulation, down to the limit of the two-track resolution. Since fritiof models nucleus-nucleus collisions by the superposition of nucleon-nucleon collisions, we conclude that there is no evidence in our data of the kinds of collective behavior predicted to give strong intermittency in heavy ion collisions.

In the interactions of relativistic heavy projectile nuclei with target nuclei there is a measurable probability for the projectile nuclei to pick up a charge during the interaction. We report here new measurements, made in a wide range of targets, of the cross sections for charge-pickup of gold nuclei with energies of 10.6 GeV/nucleon, and of silver and krypton nuclei with energies between 1.4 and 0.5 GeV/nucleon. The excitation functions of these cross sections are discussed using all the measurements available to us and indicate that there are significant decreases in the cross sections as the energies increase. A weak target dependence is seen. Previously these cross sections have been reported to have a strong, approximately quadratic, dependence on the projectile mass. This conclusion has to be modified in the light of these new measurements. Instead, we suggest that the cross sections show a strong exponential dependence on either the fractional neutron excesses or, equivalently, on the neutron to nucleon ratios of the projectile nuclei.

We have measured cross sections for the synthesis of nuclei of mass A≤4 in collisions of 14.6A GeV/c ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ nuclei with targets of Pb, Cu, and Al. The data are measured at close to center-of-mass rapidities, and are unique in their exploration of the centrality dependence of nucleosynthesis. Simple coalescence models that were used to study nucleosynthesis at lower energies are inadequate for the description of our measurements. Our data and improved models are used to extract parameters related to the size of the interaction volume at freeze-out.

The charge distribution of multifragment decays of ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ projectiles at 10.6A GeV in nuclear emulsion is fitted with a power law. The correlations between the charges emitted are given as a function of the total charge confined in fragments ${\mathit{Z}}_{\mathrm{bound}}$ for Z≥2, which is a measure of the violence of the collision. The observables of the present experiment are compared to the ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ beam at 600A MeV in the domain of limiting fragmentation and they are also reproduced by the predictions of the statistical and the percolation models. Small changes in the values of some of these observables are revealed in the two energies.

An α-cluster expansion of the Glauber multiple scattering series is used to calculate the energy transfer spectrum to the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ projectile in the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${(}^{12}$C,3α)X reaction at 2.1A Gev. Cluster-abrasion response functions are defined in terms of α-cluster wave function and the collision dynamics appropriate for heavy-ion reactions. Comparisons are made to recent quasiexclusive experimental data with good agreement found. Calculations indicate that substructures in a ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ projectile are likely to be true spectators in fragmentation, however, with virtual states of excitation in the projectile ground state making a significant contribution to the fragmentation cross section.

The slopes of the noninvariant center-of-mass energy spectrum of protons in inelastic collisions of d, α, C nuclei with carbon and tantalum targets at 4.2A GeV/c are studied. The temperatures of protons are obtained using the Boltzmann approximation of the spectra. The experimental results are compared with the calculations in the framework of the quark-gluon string model.

We investigate the possibility of using the Mott scattering between identical nuclei to assess the existence of long range QCD effects, e.g., a color van der Waals interaction, as suggested recently. We show that the inclusion of atomic effects is very important and should be considered in order to extract limits on the strength of the color van der Waals force. We compare our calculations with the analysis of a recent heavy ion experiment.

Existing formulations of the coalescence model for the formation of small nuclear clusters in nuclear collisions cannot distinguish between particle and antiparticle clusters and ignore the interactions of the cluster constituents with the other particles in the interaction region. Furthermore none of these models is kinematically fully consistent since the problem of energy conservation in the coalescence process is not dealt with directly, but buried in a phenomenological parameter, the ‘‘coalescence radius.’’ Studying the simplest case of (anti)deuteron formation, we include the effects on the coalescence rate from interactions with the medium, which allow for off-shell propagation and thus for energy conservation during coalescence, via effective medium-dependent masses for the cluster constituents. Instead of the conceptually ill-defined ‘‘coalescence radius’’ the width of the mass distributions is introduced as a fundamental parameter which, through the scattering rate in the medium, can be related to the temperature of the collision fireball. The freeze-out condition for the created clusters relates the thermodynamical parameters of the fireball to its geometric size at freeze-out and thus provides a deeper understanding of the role of the phenomenological ‘‘coalescence radius’’ in previous formulations. It automatically predicts different radius parameters and coalescence probabilities for deuterons and antideuterons. A detailed comparison of our new formulation with previous approaches is given.

The method of QCD sum rules provides a powerful technique for the calculation of properties of hadrons in terms of a number of parameters that specify various condensate matrix elements. One may hope that it will be possible to calculate some of the condensate matrix elements using effective Lagrangians. If we concentrate on quark condensates, the Nambu–Jona-Lasinio model may provide a useful model. In this work we study the relation between relativistic nuclear many-body theory and the analysis of the nucleon self-energy in nuclear matter made using QCD sum rules. This is done by introducing the fields of a bosonized version of the Nambu–Jona-Lasinio (NJL) model. Using the simplest version of the QCD sum-rule analysis, we replace the QCD order parameters in matter with related order parameters describing a Lorentz scalar and a vector field. In our mean-field analysis we find that the many-body theory, based upon the bosonization of the NJL model, is consistent with the simplest version of the QCD sum-rule calculation of the nucleon self-energy in matter.

The quark exchange model is a simple realization of an adiabatic approximation to the strong-coupling limit of quantum chromodynamics: the quarks always coalesce into the lowest energy set of flux tubes. Nuclear matter is thus modeled in terms of its quarks. We wish to study the correlations imposed by total wave-function antisymmetry when color degrees of freedom are included. To begin with, we have considered one-dimensional matter with a SU(2) color internal degree of freedom only. We proceed by constructing a totally antisymmetric, color singlet Ansatz characterized by a variational parameter λ (which describes the length scale over which two quarks in the system are clustered into hadrons) and by performing a variational Monte Carlo calculation of the energy to optimize λ for a fixed density. We calculate the q-q correlation function as well, and discuss the qualitative differences between the system at low and high density.