We investigate separately the isospin effects of Coulomb interaction and symmetry potential on the dissipation and fragmentation in the intermediate energy heavy ion collisions by using isospin-dependent quantum molecular dynamics model. The calculated results show that the Coulomb interaction induces the reductions of both isospin fractionation ratio and nuclear stopping (momentum dissipation). However, the Coulomb interaction not only does not change obviously the strong isospin effect of the symmetry potential on the isospin fractionation ratio but also does not change obviously that of in-medium two-body collision on the nuclear stopping. On the contrary, the symmetry potential induces the enhancement of the isospin fractionation ratio but it is insensitive to the nuclear stopping. Finally, the competition between the Coulomb interaction and symmetry potential induces the reductions of both isospin fractionation ratio and nuclear stopping for two forms of symmetry potentials in this paper.

A simple transport model for ultra-relativistic nucleus-nucleus collisions is proposed to investigate the effect of Pauli blocking, in the transition from the hadron phase to parton phase, on the hadronic final state. A boost invariant study of the Pauli blocking is implemented in the Monte Carlo simulation for the first time. It turns out that this partonic Pauli effect on the final hadron multiplicity in a nucleus-nucleus collision is negligible at SPS energy, around two percent at RHIC energy, but reaching ten percent at LHC energy. The higher reaction energy the stronger is the partonic Pauli effect.

Diffusion may obliterate fluctuation signals of the QCD phase transition in nuclear collisions at SPS and RHIC energies. We propose a hyperbolic diffusion equation to study the dissipation of net charge fluctuations. This equation is needed in a relativistic context, because the classic parabolic diffusion equation violates causality. We find that causality substantially limits the extent to which diffusion can dissipate these fluctuations.

We investigate the splitting and mixing of $\rho$ and $\omega$ mesons in nuclear matter. The calculations were performed on the basis of QCD sum rules and include all operators up to mass dimension-6 twist-4 and up to first order in the coupling constants. Special attention is devoted to the impact of the scalar four-quark condensates on both effects. In nuclear matter the Landau damping governs the $\rho \text{−}\omega$ mass splitting while the scalar four-quark condensates govern the strength of individual mass shifts. A strong in-medium mass splitting causes the disappearance of the $\rho \text{−}\omega$ mixing.

The hadronic spectrum obtained in the framework of a QCD-inspired schematic model is presented. The model is the extension of a previous version, whose basic degrees of freedom are constituent quarks, antiquarks, and gluons. The interaction between quarks and gluons is a phenomenological interaction and its parameters are fixed from data. The classification of the states, in terms of quark and antiquark and gluon configurations is based on symmetry considerations, and it is independent of the chosen interaction. Following this procedure, nucleon and $\Delta$ resonances are identified, as well as various penta- and hepta-quarks states. The lowest pentaquarks state is predicted at $1.5\mathrm{GeV}$ and it has negative parity, while the lowest hepta-quarks state has positive parity and its energy is of the order of $2.5\mathrm{GeV}$.

We present a relativistic dynamical model of pion photoproduction on the nucleon in the resonance region. It offers several advances over the existing approaches. The model is obtained by extending our $\pi N$-scattering description to the electromagnetic channels. The resulting photopion amplitude is thus unitary in the $\pi N$, $\gamma N$ channel space; Watson’s theorem is exactly satisfied. At this stage we have included the pion, nucleon, $\Delta \left(1232\right)$ resonance degrees of freedom. The $\rho$ and $\omega$ meson exchanges are also included, but play a minor role in the considered energy domain (up to $\sqrt{s}=1.5\mathrm{GeV}$). In this energy range the model provides a good description of all the important multipoles. We have allowed for only two free parameters—the photocouplings of the $\Delta$ resonance. These couplings are adjusted to reproduce the strength of corresponding resonant-multipoles $M_{1+}$ and $E_{1+}$ at the resonance position.

After explaining the necessity for exotic hadrons, we discuss mechanisms which could account for the production of the exotic $\Theta$-baryon. A possible important role of resonances (producing the $\Theta$ in real or virtual decays) is advanced and emphasized for selected processes. Promising experimental investigations of such resonances, and the $\Theta$ itself, are suggested. We also briefly discuss recent negative results regarding the $\Theta$-baryon.

The $\left(\gamma ,n\right)$ reaction rates of the isotopes ${}^{196,198,204}\mathrm{Hg}$ and ${}^{204}\mathrm{Pb}$ have been determined using the photoactivation technique in an energy region relevant for $p$ process nucleosynthesis. The systematic study of the ground-state $\left(\gamma ,n\right)$ reaction rates on even-even nuclei in the mass region $Z⩾78$ is complemented with these experiments. The data are compared to rates predicted in the framework of two statistical model approaches.

Quark-model hyperon-nucleon and hyperon-hyperon interactions by the Kyoto-Niigata group are applied to the two-$\Lambda$ plus $\alpha$ system in a three-cluster Faddeev formalism using two-cluster resonating-group method kernels. The model fss2 gives a reasonable two-$\Lambda$ separation energy $\Delta B_{\Lambda \Lambda }=1.41\mathrm{MeV}$, which is consistent with the recent empirical value, $\Delta B_{\Lambda \Lambda }^{\exp }=1.01\pm 0.20\mathrm{MeV}$, deduced from the Nagara event. Some important effects that are not taken into account in the present calculation are discussed.

Electron scattering from the three-nucleon bound state with two- and three-body disintegration is described. The description uses the purely nucleonic charge-dependent CD-Bonn potential and its coupled-channel extension $\mathrm{CD}\text{‐}\text{Bonn}+\Delta$. Exact solutions of three-particle equations are employed for the initial and final states of the reactions. The current has one-baryon and two-baryon contributions and couples nucleonic with $\Delta$-isobar channels. $\Delta$-isobar effects on the observables are isolated. The $\Delta$-isobar excitation yields an effective three-nucleon force and effective two- and three-nucleon currents beside other $\Delta$-isobar effects; they are mutually consistent.

As a first step to derive the interacting boson model from a microscopic nuclear Hamiltonian, we bosonize the pairing Hamiltonian in the framework of the path integral formalism, respecting both the particle number conservation and the Pauli principle. Special attention is paid to the role of the Goldstone bosons. We construct the saddle point expansion which reproduces the sector of the spectrum associated with the addition or removal of nucleon pairs.

We have performed shell-model calculations for the three odd-odd nuclei ${}^{100}\mathrm{I}\mathrm{n}$, ${}^{102}\mathrm{I}\mathrm{n}$, and ${}^{98}\mathrm{A}\mathrm{g}$, with neutron particles and proton holes around ${}^{100}\mathrm{S}\mathrm{n}$. We have used a realistic effective interaction derived from the CD-Bonn nucleon-nucleon potential, the neutron-proton channel being explicitly treated in the particle-hole formalism. Particular attention has been focused on the particle-hole multiplets, which are a direct source of information on the neutron-proton effective interaction. We present our predictions for the two lowest lying multiplets in ${}^{100}\mathrm{I}\mathrm{n}$, for which no spectroscopic data are yet available. For ${}^{98}\mathrm{A}\mathrm{g}$ and ${}^{102}\mathrm{I}\mathrm{n}$ comparison shows that our results are in very good agreement with the available experimental data.

The effect of color screening on the formation of a heavy quark-antiquark $\left(Q\overline{Q}\right)$ bound state—such as the $J∕\psi$ meson—is studied using a constituent-quark model. The response of the nuclear medium to the addition of two color charges is simulated directly in terms of its quark constituents via a string-flip potential that allows for quark confinement within hadrons yet enables the hadrons to separate without generating unphysical long-range forces. Medium modifications to the properties of the heavy meson, such as its energy and its mean-square radius, are extracted by solving Schrödinger’s equation for the $Q\overline{Q}$ pair in the presence of a (screened) density-dependent potential. The density dependence of the heavy-quark potential is in qualitative agreement with earlier studies of its temperature dependence extracted from lattice calculations at finite temperature. In the present model it is confirmed that abrupt changes in the properties of the $J∕\psi$-meson in the hadronic medium (plasma), correlate strongly with the deconfining phase transition.

The use of orthonormal wavelet basis functions for solving singular integral scattering equations is investigated. It is shown that these basis functions lead to sparse matrix equations which can be solved by iterative techniques. The scaling properties of wavelets are used to derive an efficient method for evaluating the singular integrals. The accuracy and efficiency of the wavelet transforms are demonstrated by solving the two-body $T$-matrix equation without partial wave projection. The resulting matrix equation which is characteristic of multiparticle integral scattering equations is found to provide an efficient method for obtaining accurate approximate solutions to the integral equation. These results indicate that wavelet transforms may provide a useful tool for studying few-body systems.

A continuum shell model has been constructed which allows inclusion of any nonspurious states of the core nuclei and any nonspurious states of the composite system. The resulting coupled-channels solutions are antisymmetric and translationally invariant. These wave functions can be used to calculate many nuclear phenomena, from capture reactions at astrophysical energies, to knockout reactions at low energies, to nucleon scattering and charge exchange at intermediate energies. The model is used to investigate the ${}^4\mathrm{He}(\gamma ,p){}^3\mathrm{H}$, ${}^4\mathrm{He}(\gamma ,n){}^3\mathrm{He}$, and, ${}^3\mathrm{He}(p,p){}^3\mathrm{He}$ reactions.

The “pocket formula” for the proximity potential is generalized for collisions of any two (equal or unequal) deformed nuclei, having any degree of (equal or unequal) orientations (from 0° to 180°) in space. The method is applied to axially symmetric coplaner nuclei. The case of noncoplaner nuclei will be dealt with in a separate publication.

The theory of one-nucleon removal in the stripping reaction (inelastic breakup) on a light target is extended to cover two-dimensional momentum distributions of the reaction residues with the use of realistic profile functions for the core-target and nucleon-target interactions. Examples of the calculated projected parallel- and transverse momentum distributions are given. The transverse momentum distributions, projections on a Cartesian axis perpendicular to the beam direction, show an interesting intermingling of the stripping reaction with elastic scattering of the reaction residue on the target. We also obtain doubly differential distributions of the cross section on the parallel- and transverse-momentum variables. The distributions depend strongly on the value of the magnetic quantum number $m$. They will be of importance for evaluating acceptance corrections in experiments, and they lead to alignment with the possibility of anisotropic emission of subsequent gamma rays, an interesting spectroscopic tool. Experimental data for proton stripping of ${}^8\mathrm{B}$ agree with our calculations.

Features of the dressed-quark-gluon vertex and their role in the gap and Bethe-Salpeter equations are explored. It is argued that quenched lattice data indicate the existence of net attraction in the color-octet projection of the quark-antiquark scattering kernel. The study employs a vertex model whose diagrammatic content is explicitly enumerable. That enables the systematic construction of a vertex-consistent Bethe-Salpeter kernel and thereby an exploration of the consequences for the strong interaction spectrum of attraction in the color-octet channel. With rising current-quark mass the rainbow-ladder truncation is shown to provide an increasingly accurate estimate of a bound state’s mass. Moreover, the calculated splitting between vector and pseudoscalar meson masses vanishes as the current-quark mass increases, which argues for the mass of the pseudoscalar partner of the ${\rm Y}\left(1S\right)$ to be above $9.4\mathrm{GeV}$. With the amount of attraction suggested by lattice data color-antitriplet diquarks are absent from the strong interaction spectrum.

The neutrino mean free paths (NMFP) for scattering and absorption in cold symmetric nuclear matter (SNM) are calculated using two-body effective interactions and one-body effective weak operators obtained from realistic models of nuclear forces using correlated basis theory. The infinite system is modeled in a box with periodic boundary conditions and the one particle-hole $\left(p\text{−}h\right)$ response functions are calculated using the Tamm-Dancoff approximation (TDA). For the densities $\rho =\frac{1}{2}$, 1, $\frac{3}{2}{\rho }_0$, where ${\rho }_0$ is the equilibrium density of SNM, the strength of the response is shifted to higher energy transfers when compared to a noninteracting Fermi gas (FG). This and the weakness of effective operators compared to the bare operators, significantly reduces the cross sections, enhancing the NMFP by factors of $\sim 2.5–3.5$ at the densities considered. The NMFP at the equilibrium density ${\rho }_0$ are also calculated using the TDA and random phase approximation (RPA) using zero range Skyrme-like effective interactions with parameters chosen to reproduce the equation of state and spin-isospin susceptibilities of matter. Their results indicate that RPA corrections to correlated TDA may further increase the NMFP by $\sim 25\%$ to $3–4$ times those in a noninteracting FG. Finally, the sums and the energy weighted sums of the Fermi and Gamow-Teller responses obtained from the correlated ground state are compared with those of the 1 $p\text{−}h$ response functions to extract the sum and mean energies of multi $p\text{−}h$ contributions to the weak response. The relatively large mean energy of the multi $p\text{−}h$ excitations suggests that they may not contribute significantly to low energy NMFP.