We calculate the cross sections of the elastic and inelastic breakup modes for the inclusive breakup reaction ${}^{28}\mathrm{Si}{(}^8\mathrm{B}{,}^7\mathrm{Be})$ at beam energies between 10 and 40 MeV/nucleon within a direct fragmentation model formulated in the framework of the post-form distorted-wave Born approximation. In contrast to the case of the stable isotopes, the inelastic breakup mode is found to contribute only up to $30\%$ to the total breakup cross section, which is in agreement with the recently measured experimental data. However, the high energy tail of the energy spectra of ${}^7\mathrm{Be}$ fragments is dominated by the inelastic breakup mode. The breakup amplitude is found to be dominated by contributions from distances well beyond the nuclear surface.

Predictions of the differential cross sections and spin observables of $\overrightarrow{p}{-}^3\overrightarrow{H}\mathrm{e}$ scattering at 200 and 300 MeV have been made using a microscopic model of scattering in which a complex, nonlocal optical potential is obtained in coordinate space by full folding an effective two-nucleon interaction with nuclear structure obtained from a large basis shell model calculation. Good reproduction of most data result but the need remains for a better shell model description of ${}^3$He.

We employ a recent approach to the nonrelativistic reduction of the electromagnetic current operator in calculations of electronuclear reactions. In contrast to the traditional scheme, where approximations are made for the transferred momentum, transferred energy, and initial momentum of the struck nucleon in obtaining an on-shell inspired form for the current, we treat the problem exactly for the transferred energy and transferred momentum. We calculate response functions for the reaction ${}^2\mathrm{H}{(e,e}^{\prime }p)n$ at CEBAF (TJNAF) energies and find large relativistic corrections. We also show that in plane wave impulse approximation, it is always possible to use the full operator, and we present a comparison of such a limiting case with the results incorporating relativistic effects to the first order in the initial momentum of the struck nucleon.

The dynamics of fission has been studied by solving Euler-Lagrange equations with dissipation generated through one- and two-body nuclear friction. The average kinetic energies of the fission fragments, prescission neutron multiplicities, and the mean energies of the prescission neutrons have been calculated and compared with experimental values and they agree quite well. A single value of friction coefficient has been used to reproduce the experimental data for both symmetric and asymmetric splitting of the fissioning systems over a wide range of masses and excitation energies. It has been observed that a stronger friction is required in the saddle to scission region as compared to that in the ground state to saddle region.

Improved potential solutions are presented for the inverse scattering problem for ${d+}^4$He data. The input for the inversions includes both the data of recent phase shift analyses and phase shifts from RGM coupled-channel calculations based on the $\mathrm{NN}$ Minnesota force. The combined calculations provide a more reliable estimate of the odd-even splitting of the potentials than previously found, suggesting a rather moderate role for this splitting in deuteron-nucleus scattering generally. The approximate parity-independence of the deuteron optical potentials is shown to arise from the nontrivial interference between antisymmetrization and channel coupling to the deuteron breakup channels. A further comparison of the empirical potentials established here and the double folding potential derived from the M3Y effective $\mathrm{NN}$ force (with the appropriate normalization factor) reveals strong similarities. This result supports the application of the double folding model, combined with a small Majorana component, to the description even of such a loosely bound projectile as the deuteron. In turn, support is given for the application of iterative-perturbative inversion in combination with the double folding model to study fine details of the nucleus-nucleus potential. A $d{-}^4$He tensor potential is also derived to reproduce correctly the negative ${}^6$Li quadrupole moment and the $D$-state asymptotic constant.

We develop a new method of optimized discretization for imaging the relative source from two particle correlation functions. In this method, the source resolution depends on the relative particle separation and is adjusted to available data and their errors. We test the method by restoring assumed $\mathrm{pp}$ sources and then apply the method to $\mathrm{pp}$ and IMF data. In reactions below 100 MeV/nucleon, significant portions of the sources extend to large distances $(r>\mathrm{}20\mathrm{}\hspace{0.5em}\mathrm{fm}).\mathrm{}$ The results from the imaging show the inadequacy of common Gaussian source parametrizations. We establish a simple relation between the height of the $\mathrm{pp}$ correlation function and the source value at short distances, and between the height and the proton freeze-out phase-space density.

The influence of the Landau-Zener effect on the fine structure of the cluster decay phenomenon is evidenced. Estimations of hindrance factors are reported for the ${}^{14}$C emission from ${}^{223}$Ra. The half-lives are calculated considering the cluster decay as a superasymmetric fission process appealing to the Wentzel-Kramers-Brillouin penetrabilities. The excitation of the last unpaired nucleon is considered to be due mainly to the Landau-Zener promotion mechanism. The deformation energy is computed in the framework Yukawa-plus-exponential model extended for binary systems with different charge densities and adding the specialization energy of the unpaired nucleon. The Werner-Wheeler approximation is used to compute the effective mass. Assuming molecular states during the disintegration, the superasymmetric two-center shell model is used to obtain the level scheme of the cluster decay.

The spin observables $T_{20},$ ${\kappa }_0=\frac{3}{2}{K}_y^y$ $\left(\overrightarrow{d}p\right)$, $K_{\mathrm{xz}}^y$, $K_y^y$ $\left(\overrightarrow{p}p\right),$ and $C_{\mathrm{yy}}$ are investigated for $\mathrm{dp}$ backward elastic scattering at intermediate and high energies by the invariant-amplitude method with the one-nucleon-exchange assumption. Recently observed discrepancies between the conventional calculations and the experimental data for the ${\kappa }_0{-T}_{20}$ correlation are mostly dissolved by including effects of imaginary parts as the contribution of absorption in the invariant amplitudes. The dependence of the measured $T_{20}$ and ${\kappa }_0$ on the proton-neutron relative momentum is explained by the calculation with the specification of nuclear potentials, except $T_{20}$ at high energies, for which possible solutions are investigated. Clear dependence on the imaginary parts of the amplitudes is found for $K_{\mathrm{xz}}^y$, measurements of which are suggested to be useful to distinguish between the solutions.

Based on a two-nucleon pion-production model, we have calculated the cross sections and the analyzing powers for the reactions ${}^{12,14}\mathrm{C}(p,{\pi }^{-}{)}^{13,15}{\mathrm{O}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ near and above the delta resonance, which are accessible with the present experimental facilities. As the incident energy increases, the cross section becomes sharply forward peaked and the asymmetry changes its sign for ${}^{12}\mathrm{C}.$ The asymmetry for ${}^{14}\mathrm{C}$ stays positive throughout. We have also calculated the energy dependence of the forward cross section assuming the energy-independent normalization factor.

The correlation between apparent nuclear temperatures, derived from experimental data, and the initial temperature of excited nucleus was studied within a sequential statistical model. Apparent temperatures were calculated via three methods: (1) inverse slope parameters of kinetic energy spectra of light charged particles, (2) relative population of excited states, and (3) double isotopic yield ratios. Due to the chain of subsequent emissions and side-feeding (decay of particle unstable states) the various apparent temperatures strongly differ from each other and from the initial temperature. In addition, it was found that the model of statistical evaporation is able to reproduce most of INDRA and ALADIN data, even at high excitation energies. This may mean that the apparent temperatures are essentially determined by the statistical nature of the decay of the hot nucleus and its primary fragments.

Different descriptions for varying the mass asymmetry in the fragmentation process are used to calculate the cold fission barrier penetrability. The relevance of the appropriate choice for both the description of the prescission phase and inertia coefficient to unify alpha decay, cluster radioactivity, and spontaneous cold fission processes in the same theoretical framework is explicitly shown. We calculate the half-life of all possible partition modes of nuclei of $A>\mathrm{}200\mathrm{}$ following the most recent Mass Table by Audi and Wapstra. It is shown that if one uses the description in which the mass asymmetry is maintained constant during the fragmentation process, the experimental half-life values and mass yield of ${}^{234}\mathrm{U}$ cold fission are satisfactorily reproduced.

In many existing relativistic heavy ion experiments and in future experiments from several hundred to several thousand identical hadrons (mainly pions) will be produced in each central collision event. The requirement that the outgoing many-body wave function for the identical bosons produced in these collisions be symmetric with respect to particle label exchange causes the observed momentum distributions to differ from that in the so-called “freeze out” region of the source, provided the particle emission is mainly incoherent. For high multiplicity events the symmetric many-body probability distribution for identical bosons is exceedingly complicated. A straightforward method is presented for calculating the effects of Bose-Einstein symmetrization on the observed one-body distributions for high multiplicity collision events. The method involves an expansion of the many-body probability density in powers of the source function together with a subexpansion based on the connectivity displayed in diagrammatic representations of the exchange terms. The leading symmetrization correction is shown to be proportional to the phase space particle density in the “freeze out” region of the source. Numerical results are presented for Au+Au central collisions at center-of-momentum energies of $200A$ GeV where moderate, but significant effects are obtained. The range of validity of this approach is also discussed.

Coulomb effects on ${\pi }^{\pm }$ and $K^{\pm }$ spectra in relativistic nuclear collisions are investigated. At collision energies around 1 GeV the ratio of ${\pi }^{-}$ to ${\pi }^{+}$ is enhanced several times at low transverse momenta but less at ultrarelativistic energies. We describe the ratios at SIS, AGS, and SPS energies with simple analytic models as well as more elaborate numerical models incorporating the expansion dynamics. The Coulomb effect depends on the properties of the source after the violent collision phase and provides information on source sizes, freeze-out times, and expansion velocities. Comparison with results from HBT analyses are made. Predictions for ${\pi }^{\pm }$ and $K^{\pm }$ at RHIC and LHC energies are given.

We consider the contributions of both color-singlet and octet $c\overline{c}$ bound states for studying $p_T$ dependence of $J/\psi$ suppression in quark gluon plasma (QGP). It has been found that the existence of the color-octet $c\overline{c}$ may cause a turning over of the $J/\psi$ $p_T$ distribution ${R(p}_T{;E}_T^H{,E}_T^L)$ in Pb-Pb collisions and ${R(p}_T{;E}_T^H{,E}_T^L)$ decreases with $p_T$ after a critical value ${(p}_T{)}_{\max }.$ This is quite different from the behavior of ${R(p}_T{;E}_T^H{,E}_T^L)$ in hadronic matter (HM) where it always increases with $p_T.$

We study the bremsstrahlung of virtual ω mesons due to the collective deceleration of nuclei at the initial stage of an ultrarelativistic heavy-ion collision. It is shown that electromagnetic decays of these mesons may give an important contribution to the observed yields of dileptons. Mass spectra of $e^{+}{e}^{-}$ and ${\mu }^{+}{\mu }^{-}$ pairs produced in central $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ collisions are calculated under some simplifying assumptions on the space-time variation of the baryonic current in a nuclear collision process. Comparison with the CERES data for $160A\mathrm{GeV}$ $\mathrm{P}\mathrm{b}+\mathrm{A}\mathrm{u}$ collisions shows that the proposed mechanism gives a noticeable fraction of the observed $e^{+}{e}^{-}$ pairs in the intermediate region of invariant masses. Sensitivity of the dilepton yield to the in-medium modification of masses and widths of vector mesons is demonstrated.

The $J/\psi$ production cross section considering the contributions of both color-singlet and color-octet $c\overline{c}$ channels is calculated. The result is used to study the suppression of $J/\psi$ in nuclear collisions. With absorption cross sections for $(c\overline{c}{)}_8$ ${\sigma }_{\mathrm{abs}}^8\simeq 11.5\pm 1.5\hspace{0.5em}\mathrm{mb}$ and $(c\overline{c}{)}_1$ ${\sigma }_{\mathrm{abs}}^1\simeq 0\hspace{0.5em}\mathrm{mb}$ the $p-A$ and $A-B$ data except for Pb-Pb can be explained. Possible explanations of additional suppression in Pb-Pb are discussed.

We study the surface tensions in the mixed phase of QCD at the quenched level using the dual Ginzburg-Landau theory, where the QCD-monopole condensate is the order parameter on the confinement. First, we consider the thermal mixed phase, and derive the analytical expressions for the surface tension, the boundary thickness in terms of the shape of the effective potential, and the latent heat. We study also the properties of the spherical hadron bubble in the quark-gluon-plasma phase at finite temperature. Second, we study the surface tension in the mixed phase with the external color-electric field at zero temperature. In the type-II dual superconductor, the individual flux tubes with unit color flux are stable. On the other hand, the flux tubes tend to melt into a huge tube, which is energetically favored, in the type-I case.

A generalized Lagrangian for the description of hadronic matter based on the linear $\mathrm{SU}{\mathrm{}\left(3\right)\mathrm{}}_L\times \mathrm{SU}{\mathrm{}\left(3\right)\mathrm{}}_R$ $\sigma$ model is proposed. Besides the baryon octet, the spin-0 and spin-1 nonets, a gluon condensate associated with broken scale invariance is incorporated. The observed values for the vacuum masses of the baryons and mesons are reproduced. In mean-field approximation, vector and scalar interactions yield a saturating nuclear equation of state. We discuss the difficulties and possibilities to construct a chiral invariant baryon-meson interaction that leads to a realistic equation of state. It is found that a coupling of the strange condensate to nucleons is needed to describe the hyperon potentials correctly. The effective baryon masses and the appearance of an abnormal phase of nearly massless nucleons at high densities are examined. A nonlinear realization of chiral symmetry is considered, to retain a Yukawa-type baryon-meson interaction and to establish a connection to the Walecka model.

Nucleon generalized polarizabilities are investigated within a relativistic framework, defining such quantities through a Lorentz covariant multipole expansion of the amplitude for virtual Compton scattering. The key physical ingredients in the calculation of the nucleon polarizabilities are the Lorentz invariant reduced matrix elements of the electromagnetic transition current, which can be evaluated from off-energy-shell helicity amplitudes. The evolution of the proton paramagnetic polarizability ${\beta }_{\mathrm{para}}\mathrm{}\left(q\right)\mathrm{}$ as a function of the virtual-photon three-momentum transfer $q$ is explicitly evaluated within a relativistic constituent quark model by adopting transition form factors obtained in the light-front formalism. The discussion is focused on the role played by the effects due to the relativistic approach and to the transition form factors, derived within different models.

A constructive realization of Skyrme’s conjecture that an effective pion mass “may arise as a self-consistent quantal effect” based on an ab initio quantum treatment of the Skyrme model is presented. In this quantum-mechanical Skyrme model the spectrum of states with $I=J,$ which appears in the collective quantization, terminates without any infinite tower of unphysical states. The termination point depends on the model parameters and the dimension of the SU(2) representation. Representations, in which the nucleon and ${\Delta }_{33}$ resonance are the only stable states, exist. The model is developed for both irreducible and reducible representations of general dimension. States with spin larger than 1/2 are shown to be deformed. The representation dependence of the baryon observables is illustrated numerically.