The environment generated in the midrapidity region of a high-energy nuclear collision endows the pionic degrees of freedom with a time-dependent effective mass. Its specific evolution provides a mechanism for the production of back-to-back charge-conjugate pairs of soft pions which may present an observable signal of the nonequilibrium dynamics of the chiral order parameter.

The eigenphase shifts and mixing parameters for $p-d$ elastic scattering below the deuteron-breakup threshold are calculated for the AV14 two-body potential using two different numerical methods. The excellent agreement confirms that it is possible to perform accurate numerical studies of $p-d$ scattering as well as $n-d$ scattering for energies below the three-body breakup threshold. The numerical results can be considered as benchmarks for future calculations.

Isomeric ratios and momentum distributions of nuclei produced in the fragmentation of a 60A MeV ${}^{92}\mathrm{Mo}$ beam on a thin ${}^{27}\mathrm{Al}$ target have been studied in detail. A strong dependence of the isomeric ratio on the structure of the isomer and on the reaction mechanism has been observed for the first time at intermediate energies. The results are quantitatively reproduced in a framework of kinematical and statistical models of nuclear reactions.

Event-by-event fluctuations and correlations between particles produced in relativistic nuclear collisions are studied. The fluctuations in positive, negative, total, and net charge are closely related through correlations. In the event of a phase transition to a quark-gluon plasma, fluctuations in total and net charge can be enhanced and reduced, respectively, which, however, is very sensitive to the acceptance and centrality. If the colliding system experiences strong density fluctuations due, e.g., to droplet formation in a first-order phase transition, all fluctuations can be enhanced substantially. The importance of fluctuations and correlations is exemplified by event-by-event measurement of the multiplicities of $J/\Psi \mathrm{’}\mathrm{s}$ and charged particles since these observables should anticorrelate in the presence of comover or anomalous absorption.

The microscopic analysis of experimental data in ${}^{160,162}\mathrm{Tm}$ is presented within the two-quasiparticle-phonon model. The model includes the interaction between odd quasiparticles and their coupling with core vibrations. The coupling explains naturally the attenuation of the Coriolis interaction in rotating odd-odd nuclei. It is shown that the competition between the Coriolis and neutron-proton interactions is responsible for the signature inversion phenomenon.

A self-consistent shell-model continuum-random-phase approximation approach is developed to evaluate the partial proton widths of isobaric analog resonances in spherical nuclei from a wide mass interval. The results are found to be in reasonable agreement with the experimental data. An attempt to deduce the single-particle spectroscopic factors from the comparison of the experimental and calculated widths is undertaken. The direct proton-decay branching ratio for the isovector giant monopole resonance in ${}^{208}\mathrm{Bi}$ is estimated in connection with recent experimental data.

The nucleus ${}^{104}\mathrm{Pd},$ populated in the electron capture and ${\beta }^{+}$ decay of ${}^{104}\mathrm{Ag},$ has been investigated by means of $\gamma -\gamma$ coincidence, $\gamma -\gamma$ angular correlation, and K internal conversion coefficient measurements. The results have led to an improved knowledge of the decay scheme, to spin-parity assignment to several levels, and to the determination of $E2/M1\mathrm{}$ mixing ratios for the most intense transitions. Information on $E0\mathrm{}$ transitions between $0^{+}$ states and between states of same $J\ne 0$ has also been deduced. The new spectroscopic data have been used to give an updated version of the decay scheme of ${}^{104}\mathrm{Pd}.$

The statistical scission model is applied to fission fragment angular distributions from heavy-ion induced reactions. It is shown that the statistical scission model predicts angular distributions in good agreement with those measured from heavy-ion induced fission of some reaction systems where the fission barrier has vanished or is very small relative to the nuclear temperature. The statistical variances extracted from these model calculations are compared with their corresponding values from a microscopic theory, which includes nuclear pairing interaction. It is found that the values of statistical variance $S_0^2$ are very sensitive to the pairing energy. The effects of pairing interaction on the fragment angular distributions are illustrated and discussed.

We present calculations of differential cross sections for Compton scattering from the proton, using amplitudes calculated to fourth order in heavy baryon chiral perturbation theory. We compare with available data up to 200 MeV. We find that the agreement for angles up to 90° is very good over the whole energy range, but that at more backward angles the agreement decreases above about 100 MeV and fails completely above the photoproduction threshold.

We study the low energy pion-hyperon interaction considering effective nonlinear chiral invariant Lagrangians including pions, ρ mesons, σ mesons, hyperons, and corresponding resonances. Then we calculate the S- and P-wave phase shifts, total cross sections, angular distributions, and polarizations for the momentum in the center-of-mass frame up to $k=400\mathrm{}$ MeV. With these results we discuss the $\mathrm{CP}$ violation in the $\overrightarrow{\Xi }\Lambda \pi$ and $\overrightarrow{\Omega }\Xi \pi$ weak decays.

The time dependent Schrödinger equation is solved analytically for a simplified model of moving infinite walls. A new knockout mode is described which might occur during heavy ion collisions. The outer shell nucleons are ionized due to the increase of level energy when two nuclei are approaching fast enough. This is analogous to the Mott effect but in contrast occurs only if the reaction time is short enough that no common ionization threshold in the compound system is established. To demonstrate this pure nonequilibrium effect a simulation of realistic heavy ion collision by a nonlocal Boltzmann equation is performed.

In an effort to better determine the ${}^7\mathrm{Be}(p,\gamma {)}^8\mathrm{B}$ reaction rate, we have performed inclusive and exclusive measurements of the Coulomb dissociation of ${}^8\mathrm{B}.$ The former was a study of longitudinal momentum distributions of ${}^7\mathrm{Be}$ fragments emitted in the Coulomb breakup of intermediate energy ${}^8\mathrm{B}$ beams on Pb and Ag targets. Analysis of these data yielded the $E2\mathrm{}$ contribution to the breakup cross section. In the exclusive measurement, we determined the cross section for the Coulomb breakup of ${}^8\mathrm{B}$ on Pb at low relative energies in order to infer the astrophysical S factor for the ${}^7\mathrm{Be}(p,\gamma {)}^8\mathrm{B}$ reaction. Interpreting the measurements with first-order perturbation theory, we obtained $S_{E2\mathrm{}}{/S}_{E1\mathrm{}}{=4.7\mathrm{}}_{-1.3}^{+2.0\mathrm{}}\times {10}^{-4}$ at $E_{\mathrm{rel}}=0.6\mathrm{}\hspace{0.5em}\mathrm{MeV},$ and $S_{17}{\mathrm{}\left(0\right)=17.8\mathrm{}}_{-1.2}^{+1.4\mathrm{}}\hspace{0.5em}\mathrm{eV}\mathrm{}\mathrm{b}.$ Semiclassical first-order perturbation theory and fully quantum mechanical continuum-discretized coupled channels analyses yield nearly identical results for the $E1\mathrm{}$ strength relevant to solar neutrino flux calculations, suggesting that theoretical reaction mechanism uncertainties need not limit the precision of Coulomb breakup determinations of the ${}^7\mathrm{Be}(p,\gamma {)}^8\mathrm{B}$ S factor. A recommended value of $S_{17}\mathrm{}\left(0\right)\mathrm{}$ based on a weighted average of this and other measurements is presented.

The technique of isomer decay tagging (IDT) has been recently implemented at Oak Ridge National Laboratory to identify strongly deformed bands above a short-lived isomer in ${}^{80}\mathrm{Y}.$ The IDT method provides very clean reaction channel selection of prompt in-beam decays by correlating these events with delayed events detected at the focal plane of a recoil separator. Using this method, coincident transitions above and below a $4.7\hspace{0.5em}\mu \mathrm{s}$ isomer in ${}^{80}\mathrm{Y}$ were observed. The placement of this isomer in the ${}^{80}\mathrm{Y}$ level scheme is further confirmed and the deformed structure of the rotational bands built on the isomer is discussed.

Cross sections for production of ${}^6\mathrm{He},$ ${}^6\mathrm{Li},$ ${}^7\mathrm{Li},$ and ${}^7\mathrm{Be}$ in the $\alpha +\alpha$ reaction were measured at bombarding energies of 159.3, 279.6, and 619.8 MeV and are found to decrease rapidly with increasing energy. These cross sections are essential for the calculation of the rate of nucleosynthesis of the lithium isotopes in the cosmic rays and thereby play a key role in our understanding of the synthesis of Li, Be, and B. The results for ${}^6\mathrm{Li}$ differ significantly from the tabulated values commonly used in cosmic ray production calculations and lead to lower production of ${}^6\mathrm{Li}.$

The reduction of the two-fermion Bethe-Salpeter equation in the framework of light-front dynamics is studied for the Yukawa model. It yields auxiliary three-dimensional quantities for the transition matrix and the bound state. The arising effective interaction can be perturbatively expanded in powers of the coupling constant $g_s$ allowing a defined number of boson exchanges; it is divergent and needs renormalization; it also includes the instantaneous term of the Dirac propagator. One possible solution of the renormalization problem of the boson exchanges is shown to be provided by expanding the effective interaction beyond single boson exchange. The effective interaction in ladder approximation up to order $g_s^4$ is discussed in detail. It is shown that the effective interaction naturally yields the “box counterterm” required to be introduced ad hoc previously. The covariant results of the Bethe-Salpeter equation can be recovered from the corresponding auxiliary three-dimensional quantities.

Angular distributions of elastic scatterings for the ${}^{19}\mathrm{F}{+}^{208}\mathrm{Pb}$ system were measured at six energies around the Coulomb barrier. By means of a phenomenological optical model analysis, it is found that the real and imaginary potentials show a pronounced energy dependence. The real parts of potentials extracted from the fusion data are similar to those from the elastic data. A comparison with the neighboring systems of ${}^{16}\mathrm{O}{+}^{208}\mathrm{Pb}$ and ${}^{16}\mathrm{O}{+}^{209}\mathrm{Bi}$ reveals that the effects of the ${}^{19}\mathrm{F}$ deformations in the entrance channel play an important role in the fusion reaction. Based on the deformed and energy dependent barrier penetration model, the calculation results of the fusion cross sections and mean-square spin distribution agree with the experimental data well. Furthermore, it is indicated that the enhancement of fusion cross sections is attributed to the dynamic polarization effects around the barrier, and to the static deformation effects further below the barrier.

We study the role of Coulomb and surface effects on the phase transition from dense nuclear matter to a mixed phase of nuclear and kaon-condensed matter. We calculate corrections to the bulk calculation of the equation of state (EOS) and the critical density for the transition by solving explicitly for spherical, cylindrical, and planar structures. The importance of Debye screening in the determination of the charged particle profiles is studied in some detail. We find that the surface and Coulomb contributions to the energy density are small but that they play an important role in the determination of the critical pressure for the transition, as well as affecting the size and geometry of favored structures. This changes the EOS over a wide range of pressure and consequently increases the maximum mass by $\sim {0.1M}_{\odot }.$ Implications for transport properties of the mixed phase are also discussed.

Jacobi shape transition from noncollective oblate to super or hyperdeformed collective prolate or triaxial shape taking place in rotating nuclei as in the case of gravitating rotating stars is studied in fp shell nuclei ${}^{44}\mathrm{Ti},$ ${}^{48}\mathrm{Cr},$ ${}^{52}\mathrm{Fe},$ and ${}^{56}\mathrm{Ni}.$ The cranked Nilsson-Strutinsky method is used to detect such transition. The method of tuning the angular velocity to get fixed spin is utilized in these calculations. Pairing is not taken into account since Jacobi transition occurs only at very high spin where pairing correlations would have already vanished. Our results show that all the four nuclei considered in this work are good candidates for detecting the Jacobi shape transition.