In the framework of QCD at finite temperature, we have obtained dissipative factors for the effective potential between $q$ and $\mathrm{q¯}$ which would partly explain the $J/\psi$ suppression in the quark gluon plasma (QGP). The derivation of the dissipative potential in the QGP is presented and the case in the hadron matter (HM) is briefly discussed. The suppression effects are numerically estimated based on simple approximations and a comparison with that caused by the Debye screening mechanism is also presented.

We study the $N\pi N$ coupling, in the framework of a QCD-inspired confining Nambu-Jona-Lasinio model. A simple relativistic confining and instantaneous quark model is reviewed. The Salpeter equation for the $\mathrm{qqq}$ nucleon and the $q\mathrm{q¯}$ boosted pion is solved. The $f_{n\pi n}$ and $f_{n\pi \Delta }$ couplings are calculated and they turn out to be reasonably good. The sensibility of $f_{n\pi n}$ and $f_{n\pi \Delta }$ to confinement, chiral symmetry breaking, and Lorentz invariance is briefly discussed.

We study nuclear stopping in high energy nuclear collisions using the constituent quark model. It is assumed that wounded nucleons with a different number of interacted quarks hadronize in different ways. The probabilities of having such wounded nucleons are evaluated for proton-proton, proton-nucleus, and nucleus-nucleus collisions. After examining our model in proton-proton and proton-nucleus collisions and fixing the hadronization functions, it is extended to nucleus-nucleus collisions. It is used to calculate the rapidity distribution and the rapidity shift of final-state protons in nucleus-nucleus collisions. The computed results are in good agreement with the experimental data on ${}^{32}\mathrm{S}{+}^{32}\mathrm{S}$ at $E_{\mathrm{lab}}=200A$ GeV and ${}^{208}\mathrm{Pb}{+}^{208}\mathrm{Pb}$ at $E_{\mathrm{lab}}=160A$ GeV. Theoretical predictions are also given for proton rapidity distribution in ${}^{197}\mathrm{Au}{+}^{197}\mathrm{Au}$ at $\sqrt{s}=200A$ GeV (BNL-RHIC). We predict that the nearly baryon-free region will appear in the midrapidity region and the rapidity shift is 〈Δy〉=2.24.

The effect of (i) the phase transition between a quark gluon plasma (QGP) and a hadron gas and (ii) the number of resonance degrees of freedom in the hadronic phase on the single inclusive distributions of 16 different types of produced hadrons for Au+Au collisions at the Brookhaven Alternating Gradient Synchroton (AGS) energies is studied. We have used an exact numerical solution of the relativistic hydrodynamical equations without free parameters which, because of its (3+1)-dimensional character, constitutes a considerable improvement over the classical Landau solution. We assume chemical equilibration and we use two different equations of state (EOS): one describing a phase transition from QGP to the hadronic phase and two versions of a purely hadronic EOS; we find that the first one gives an overall better description of the Au+Au experimental data at AGS energies. We reproduce and analyze measured meson and proton spectra and also make predictions for antiprotons, deltas, antideltas, and hyperons. The low $m_t$ enhancement in ${\pi }^{-}$ spectra is explained by baryon number conservation and strangeness equilibration. The sensitivity of various production channels to the EOS is analyzed.

Many-particle correlations due to Bose-Einstein interference are studied in ultrarelativistic heavy-ion collisions. We calculate the higher order correlation functions from the two-particle correlation function by assuming that the source is emitting particles incoherently. In particular parametrizations of and relations between longitudinal, sidewards, outwards, and invariant radii and corresponding momenta are discussed. The results are especially useful in low statistics measurements of higher order correlation functions. We evaluate the three-pion correlation function recently measured by NA44 and predict the two-pion-two-kaon correlation function. Finally, many-particle Coulomb corrections are discussed.

In kaon electroproduction, ${p(e,e}^{\prime }{K}^{+})Y\to$ $(Y=\Lambda$,${\Sigma }^0)$, hyperon polarization is an observable which arises from interference between resonant ${(N}^{*}$,${\Delta }^{*})$ and nonresonant amplitudes involving the hyperon anomalous magnetic form factors $F_2^{\Lambda }{(q}^2)$ and $F_2^{\Sigma \Lambda }{(q}^2)$. Within the framework of an effective hadronic field Lagrangian model we investigate the possibility suggested by Williams and Truman that the $\Lambda$/${\Sigma }^0$ polarized cross section ratio may be approximately proportional to the form factor ratio $F_2^{\Lambda }{/F}_2^{\Sigma \Lambda }$ and independent of the dominant $N^{*}$ amplitude. We illustrate both the simplified case where the relation between the form factor and polarized cross section ratio is an identity and the sensitivity due to dynamical assumptions about nearby resonances and the $g_{\mathrm{KN}\Lambda }$ coupling constant.

Effective masses of $\sigma$, $\omega$, $\pi$, and $\rho$ mesons in nuclear matter are calculated based on a cutoff field theory. Instead of the traditional density-Feynman representation, we adopt the particle-hole-antiparticle representation for nuclear propagators so that unphysical components are not included in the meson self-energies. For an estimation of the contribution from the divergent particle-antiparticle excitations, i.e., vacuum polarization in nuclear matter, the idea of the renormalization group method is adopted. In this cutoff field theory, all the counterterms are finite and calculated numerically. It is shown that the predicted meson masses converge even if the cutoff $\Lambda$ is changed as long as $\Lambda$ is sufficiently large and that the prescription works well also for so-called nonrenormalized mesons such as $\pi$ and $\rho$. According to this method, it is concluded that meson masses in nuclear matter have a weak dependence on the baryon density.

We reexamine the effects of antisymmetry on the antiquarks in the nucleon sea arising from gluon exchange and pion exchange between confined quarks. While the effect is primarily to suppress down relative to up antiquarks, this is numerically insignificant for the pion terms.

Color transparency is the vanishing of initial and final state interactions, predicted by QCD to occur in high momentum transfer quasielastic nuclear reactions. For specific reactions involving nucleons, the initial and final state interactions are expected to be dominated by exchanges of pions. We argue that these interactions are also suppressed in high momentum transfer nuclear quasielastic reactions; this is “chiral transparency.” We show that studies of the $e{}^3\mathrm{He}\to e^{\prime }{\Delta }^{++}\mathrm{nn}$ reaction could reveal the influence of chiral transparency.

The role of dynamics in spin observables for pseudoscalar meson photoproduction is investigated using a density matrix approach in a multipole truncated framework. Extraction of novel rules for $\gamma p\to {\pi }^{+}n,\hspace{0.5em}{K}^{+}\Lambda$, and $\eta p$ reactions based on resonance dominance, and on other broad and reasonable dynamical assumptions, are discussed. Observables that are particularly sensitive to missing nucleonic resonances predicted by quark-based approaches, are singled out.

Measurements of the interaction rates of the solar neutrino lines of ${}^7$Be and $\mathrm{pep}$ can be used, independent of solar models, to test whether electron flavor is conserved, to determine survival probabilities of electron-type neutrinos at specific energies, and to test for the existence of sterile neutrinos. We present analytic descriptions of these tests. We also illustrate by numerical simulations, assuming matter-enhanced and vacuum neutrino oscillations, what measurements of solar neutrino lines can teach us about neutrino masses and mixing angles.

The $(\gamma ,d)$ and $(\gamma ,t)$ reactions on ${}^6$Li were studied at average (tagged) photon energies of 59 and 75 MeV. Differential cross sections were obtained at five different angles (30$°<~{\theta }_{\mathrm{lab}}<~150°)$, from which the integrated-over-angle cross sections for the $d_0$ and $t_0$ channels were determined. The experimental results are discussed in terms of a cluster model calculation.

Reanalysis of $\alpha +\alpha$ reaction data at 61.5, 80.8, 118.9, 139.2, and 158.2 MeV [B.G. Glagola et al., Phys. Rev. C 25, 34 (1982)] suggests that inconsistent normalizations have been used for calculating cross sections for ${}^6$He, ${}^{6,7}$Li, and ${}^7$Be production. Corrected values are presented, notably for ${}^6$Li, which may have significant implications for astrophysics calculations.

Giant monopole resonance strengths were obtained from small angle inelastic alpha scattering ${\mathrm{on}}^{58}$Ni ${\mathrm{and}}^{208}$Pb using deformed potential and folding models. Folding model analyses increase the sum rule strength in both nuclei, with 160% of the E0 sum rule required to fit the 13.7-MeV state in Pb. Significant contributions from other multipolarities could be excluded. The E0 strength identified ${\mathrm{in}}^{58}$Ni is shown to be about 42% of that identified ${\mathrm{in}}^{208}$Pb.

Using a (3+1)-dimensional solution of the relativistic Euler-equations for Pb+Pb at 160$A$ GeV, space-time extensions of kaon emission zones are calculated from space-time densities and compared to the inverse widths of two-kaon Bose-Einstein correlation functions. The comparison shows a satisfactory agreement and it is concluded that because of the Gaussian shape of the kaon correlation functions, the space-time parameters of the kaon source can be calculated directly from space-time densities. In the case of intensity interferometry of identical pions this simplification is not recommended when applying Gaussian fits because of the present strong effects of resonance decays. The whole discussion is based on the assumption that hadron emission in ultrarelativistic heavy-ion collisions is purely chaotic or that coherence is at least negligible.

We report on possible effects of quantum-mechanical interferences between gravitational forces and the nucleus-nucleus Coulomb interaction. We show that, although very small, these effects could be measured on using low-energy scattering between identical heavy nuclei. For the system ${}^{208}\mathrm{Pb}{+}^{208}\mathrm{Pb}{(E}_L=5\mathrm{}\mathrm{MeV})$. The angular precision needed would be about $0.001°$.

Both dilepton and charm production at RHIC are considered to be important signatures for quark-gluon plasma production. Recently it was argued by Gavin et al. that the background from semileptonic correlated charm decays is so large that it makes dilepton measurements virtually impossible. We show that this conclusion is in fact reversed if the energy loss due to a secondary interaction of charmed quarks is included.

The differential cross sections from the scattering of 350 MeV ${}^7$Li ions from ${}^{12}$C and from ${}^{28}$Si have been analyzed by both a global and a numerical inverse scattering theory. Statistically significant fits to both high quality data sets have been found from which the associated effective local interaction potentials between the colliding ions have been deduced. The interactions obtained by the different approaches are radically different. A priori physical information about the nature of realistic effective interactions is required to ascertain which, if any, is the most reasonable one for use in analyses of other reaction data from these systems.

In this paper, the normal and the intruder 2p-2h bands in even ${}^{112-118}$Sn isotopes have been studied through configuration mixing calculation in the framework of IBM-2. The states belonging to the normal and the intruder bands have been calculated separately and then allowed to mix by using a simple band-mixing Hamiltonian. Energy values, $E2\mathrm{}$ transition probabilities, and quadrupole moments of the first 2${}^{+}$ state have been calculated and compared with the experimental values.

Brenner et al. [1] recently reported the apparent evidence for a spherical shell at N=164. Some arguments are given which may make it necessary to reconsider this conclusion.