Table of contents

The isotopic yields for the spontaneous cold ternary alpha-accompanied fission of were calculated using a double folding potential generated by Coulomb plus M3Y nucleon - nucleon forces and realistic fragment ground state deformations. The penetrabilities through the ternary fragmentation barrier were obtained within the one-dimensional WKB approximation.

We review some of the developments in the experimental and theoretical understanding of cluster symmetries. We pay particular attention to the association of clustering with highly deformed configurations and to the ways in which the symmetries of the nuclear interaction give rise to many different cluster modes. On the experimental side we concentrate particularly on those experimental studies of clustering where resonant particle spectroscopy is applied to breakup reactions, using position-sensitive, charged-particle detectors. We investigate the role of clustering and cluster models in nuclear reactions and examine the recent evidence for -cluster chain configurations in the light even - even nuclei from to . On the theoretical side, we briefly introduce fully microscopic models, but concentrate mainly on Bloch - Brink and local potential cluster models. The double-resonance mechanism, band-crossing model and recent work on explicit models of the interaction between deformed nuclei are also summarized.

We apply the newly improved Batalin - Fradkin - Tyutin (BFT) Hamiltonian method to the chiral Schwinger model in the case of the regularization ambiguity a>1. We show that one can systematically construct the first class constraints by the BFT Hamiltonian method, and also show that the well-known Dirac brackets of the original phase space variables are exactly the Poisson brackets of the corresponding modified fields in the extended phase space. Furthermore, we show that the first class Hamiltonian is simply obtained by replacing the original fields in the canonical Hamiltonian by these modified fields. Performing the momentum integrations, we obtain the corresponding first class Lagrangian in the configuration space.

The four texture zero mass matrices have been investigated in the context of the latest data regarding , elements, angles of the unitarity triangle, etc. The present model, apart from accommodating GeV, is able to reproduce , and predicts to be in the range 0.005 - 0.012. Furthermore, the angles of the unitarity triangle, relating to the CP-violating asymmetries, have been predicted to be with taking two ranges, viz, and . The implications of values on the CP-violating phase of as well as some rare B decays have also been investigated.

By introducing in the hydrodynamic model, i.e. in the hydrodynamic equations and the corresponding boundary conditions, the higher-order terms in the deviation of the shape, we obtain to second order the Korteweg de Vries equation (KdV). The same equation is obtained by introducing in the liquid drop model (LDM), i.e. in the kinetic, surface and Coulomb terms, the higher terms to second order. The KdV equation has cnoidal waves as steady-state solutions. These waves could describe the small anharmonic vibrations of spherical nuclei up to the solitary waves. The solitons could describe the preformation of clusters on the nuclear surface. We apply this nonlinear LDM to the alpha formation in heavy nuclei. We find an additional minimum in the total energy of such systems, corresponding to the solitons as clusters on the nuclear surface. By introducing the shell effects we choose this minimum to be degenerated with the ground state. The spectroscopic factor is given by the ratio of the square amplitudes in the two minima.

In this paper we have analysed elastic scattering data at 200 MeV using the frameworks of the relativistic Dirac optical model and the non-relativistic (Brueckner-theory-based) optical model. We find that the non-relativistic Brueckner-theory-based approach predicts the elastic scattering data at 200 MeV more satisfactorily at all angles compared to the relativistic Dirac optical model approach.

Effects of the distortion of the pion wavefunction in the pionic double charge exchange on are studied in the framework of the pion - nucleus optical potential and in the proton - neutron quasiparticle random phase approximation. The agreement of the calculated p-wave cross section with existing experimental data is improved with respect to the plane wavefunction results. The resonant behaviour of the cross section at 50 MeV is analysed.