Table of contents

The author considers the possibility of the existence of charmonium-four-quark states to explain the recently observed anomalies in psi decays. The photoproduction cross section appears to give a reasonable signal for the production of the charmonium-pion state.

The authors demonstrate that though some relativistic effects in the nucleon momentum distribution in the deuteron are important in the momentum region k>0.3 GeV/c, these effects can nevertheless not account for the discrepancy between the experimentally measured distribution and the results of theoretical calculations based on two-nucleon wavefunctions. Apart from this, the role of the P wave in the nucleon momentum distribution in the deuteron is discussed.

The authors investigate the effect of the one-body ( rho ₁) and two-body ( rho ₂) relativistic corrections to the charge density on the differential cross section at 0 degrees for deuteron photodisintegration. rho ₁ also includes the kinematical contributions due to the wavefunction transformations. The effect of rho ₂ evaluated in pseudovector pi N coupling adds coherently to that of rho ₁, leading to a noticeable improvement of the fit to the data. This improvement is not obtained using the pseudoscalar pi N coupling.

In a crystal ball all continuum gamma rays of a cascade from the entry state to a yrast state can in principle be observed. If one assumes a preference for stretched E2 transitions one expects a 'doughnut'-shaped angular distribution where the symmetry axis gives the direction of the entry-state angular momentum approximately. The computer code ICARUS, which simulates gamma -ray cascades after heavy-ion fusion reactions, is extended to include angular distributions. By Monte-Carlo simulation one tests how accurately one can extract the direction of the entry angular momentum as a function of excitation energy and angular momentum of the entry state. For ¹⁵⁸Er the mean error varies from 20 degrees -40 degrees depending on excitation energy and angular momentum. The entry-state weighted mean error is 25 degrees .

The decay of ⁶Li*(0⁺, 1; 3.56 MeV) to alpha +d occurs due to the admixture of continuous-spectrum 0^- states with the 0⁺ state considered. To calculate the width, Gamma , of this decay, the authors have elaborated a method of fractional parentage coefficients for a six-nucleon system in the continuous spectrum. Finally, after numerical calculations, they obtained an extremely small value for Gamma .

The levels of ⁷⁴Kr were identified to a tentative 20⁺ level in the reaction ⁵⁸Ni(¹⁹F, p2n gamma ) by using a neutron multiplicity filter. The moment of inertia of the yrast cascade exhibits the first high-spin double discontinuity in such light nuclei, above 10⁺ and 14⁺. Both discontinuities are interpreted as arising from the crossing of rotation aligned bands.

Supersymmetric SU(2)_L(X)U(1) horizontal models are studied. The non-renormalisation theorems of supersymmetry are used to make the mass generation and flavour mixing natural. For three families, the authors study the fermion mass matrix generation mechanism as a radiative effect due to horizontal interaction, using various representations of the gauge horizontal groups SU(2)_H and SU(3)_H. An attractive possibility leading to a realistic mass matrix is found.

The GLAM-GW (Gaillard and Lee, 1974; Altarelli and Maiani, 1974; Gilman and Wise, 1979) method of decoupling is applied to the flavour-conserving non-leptonic weak interaction mediated by W and Z exchange in SU(3)*SU(2)*U(1) to derive an effective Hamiltonian in which the weak bosons and the heavy quarks are decoupled. While the theoretical methods are quite general, numerical results for the effective Hamiltonian are given for a three-quark effective theory with u, d and s quarks active, since this is of interest for weak interactions in nuclear physics. Calculations are performed in the alpha =0 gauge and the ms subtraction scheme. The authors' numerical results are given for Lambda ₅(ms)=0.25 GeV and Lambda ₅(ms)=0.35 GeV.

Fixed momentum transfer dispersion relations for gamma gamma to pi pi are evaluated in the resonance dominance approximation. Simple expressions are given so as to allow easy comparison with experimental results on ee to ee pi ⁺ pi ^-, as they become available. The f resonance is predicted to have a complex coupling to gamma gamma , which has a pronounced effect on its interference with the dominant Born term.

Amplitudes for NN to pi d are fitted to data up to 580 MeV and are compared with the predictions of Blankleider (1980) and of Niskanen (1978). In this analysis, high partial waves are fixed at values calculated by Blankleider, and the phases of low partial waves are constrained (except for ³P₁) to his phases. Further data on iT₁₁, sigma (x0 mod iT₁₁) and T₂₀ are needed in order to fix all partial waves with orbital angular momentum L<or=2 in the pi d channel.

The total p-¹²C interaction cross section, differential and integrated cross sections, polarisation and the spin-rotation function of 1 GeV protons elastically scattered by ¹²C have been calculated on the basis of the alpha -particle model with dispersion. The calculated characteristics of p-¹²C scattering contain no fitting parameters and are found to be in agreement with the experimental data.

The differences between the charge distributions of neighbouring nuclei determined by electron elastic scattering are compared with calculations using the single-particle potential model with a standard potential.

A new derivation of correction terms to the primitive semiclassical amplitude for multiple inelastic scattering is presented. It is shown that a modification of the path integral method used by Pechukas yields correction terms in agreement with the results obtained in a recent paper by Sukumar and Brink.

The (n, 2n) reaction cross sections on ¹³⁴Ba, ¹⁴²Nd, ¹⁵⁰Nd and ¹⁴⁴Sm have been measured by the activation method. The results are compared with the calculations accounting for nucleon evaporation and pre-equilibrium emission.

A method for the joint analysis of coincident and inclusive electrofission data is developed in order to minimise effects of the model dependence of data interpretation. Explicit calculations of the (e, e'f) angular correlations are presented. The potentialities of the method in the study of sub- and near-barrier properties of the fission process and in the study of the giant resonance fission mode are discussed.