Table of contents

The authors show how the Schwinger model may be solved by means of the nonperturbative gauge technique.

The Reggeon-photon coupling analogy, which relates the coupling of the natural-parity trajectories (P,f, omega , rho ,A₂) at any vertex to that of the photon, is used to predict successfully a wide variety of elastic and total cross sections. As a special case, the authors predict the cross sections for gamma p to Vp where V is any vector meson ( rho , omega , phi , psi , Upsilon or their daughters) and thence obtain an excellent prediction of the recently measured sigma ^tot( gamma p) at high energies.

An iterative approach to determine directly the best Hartree-Fock one-body density rho is extended by expressing rho in terms of a core and a valence part and allowing for general crossings of occupied and unoccupied levels in the valence part. Results are shown for ¹⁵²Sm and a microscopic analysis of the core structure of deformed light nuclei is carried out.

A version of a relativistic Hamiltonian theory is developed in which the four-momentum of the spurion lies on the light cone. A new point of this scheme is a specific regularisation by which the singularities accompanying each field theory in light-front variables are removed in all diagrams. The unitarity and causality conditions are analysed in detail. It is shown that the choice of regularisation is defined by the causality condition. In the framework of the scheme developed, a quasipotential-type equation for the two-particle scattering amplitude is obtained. Various forms of this equation and their relations with previous quasipotential equations are considered.

The inclusive production of pseudoscalar mesons is considered in a parameter-free Mueller-Regge model with absorption corrections. The inclusive cross sections for fixed t and fixed M²/s are given.

The gamma -analogy hypotheses for Reggeon couplings are used to predict the dominant P, f, omega , rho and A₂ exchanges in pi ^+or-p, K^+or-p, pp and pp elastic scattering. The couplings are all determined by the vector-meson-photon couplings f_{omega gamma} and f_{rho gamma} , with only a small allowance for f- omega degeneracy breaking. Then the only unknown is the P:f ratio. When this has been determined (as a function of t) the authors can predict successfully sigma ^tot and d sigma /dt for all the above processes, and make reasonable estimates of the decay rates for rho , f, g, h to pi pi and f, A₂, omega *, g, h to KK.

In the three-quark shell model with SU(6)(X)O(3) symmetry the baryonic states assigned to the (56,0⁺)₀ and (70,1^-)₁ multiplets are discussed. Superposed on the confining potential, the short-range quark-quark interaction is taken to be Coulomb-like. In order to reproduce the large splitting between the two singlet Lambda states in the (70,1^-)₁ multiplet, an extra spin-orbit term originating from the confining potential is introduced, which is supposed to come from scalar coupling, SU(3) breaking is put in by taking different masses for the strange and non-strange quarks, and is treated in an exact way. General mass formulae for all (56,0⁺)₀ and (70,1^-)₁ resonances are given and a fit to the spectrum has been performed.

The authors consider eta gamma and eta ' gamma decays of the Upsilon , finding them less important than for the psi . The authors also estimate some hadronic modes and find two-body charmed and strange modes approximately equal. Important two-body decays have widths of tens of eV, out of an expected total width of 20-30 keV.

A simple potential model for the neutron-proton system which describes accurately both the experimental ³D₂ phase-shifts and the Reid ³S₁-³D₁ phase parameters is presented. The nonlocal component of the total interaction is repulsive. The problem of describing both the present experimental ³S₁-³D₁ and the ³D₂ phase parameters together with the quadrupole moment of the deuteron is discussed.

A two-range central-plus-tensor potential is assumed for the effective nucleon-nucleon interactions in the shell-model calculation of N=28, 29 and 30 isotopes. A model space of (f₇2/^n-1, (_3/2, p₁2/, f_5/2)) is assumed for the proton configuration of N=28 nuclei. The correct isospin wavefunctions proposed by Osnes (1970) are considered. For N=29 and 30 nuclei, the protons are restricted to the 1f_7/2 orbit, and the valence neutrons are allowed to distribute in the 2p_3/2, 2p_1/2 and 1f_5/2 shells. Energy level spectra for N=28, 29 and 30 nuclei are calculated in a Talmi-type calculation. The calculated results are in good agreement with the experimental observations.

In calculations of alpha decay, alpha transfer and knock-out reactions the relative wavefunction of the alpha particle is generated in a suitable potential. The relation between results obtained with a phenomenological potential and a folding model with and without exchange is discussed. It is suggested that unexpectedly large radii deduced for both the phenomenological potentials and the alpha -particle wavefunctions can be understood as a compensation for the neglect of antisymmetrisation.

In preparation for a microscopic treatment of the low-energy, nucleus-nucleus optical potential, the static part of this potential (the pure one-channel problem) is reconsidered. Asymptotic nucleus-nucleus states are constructed via momentum-projection techniques of Rouhaninejad-Yoccoz type (1966) applied to localised fragment states, and are orthogonalised by diagonalising an overlap kernel. The relationship of the method to the resonating-group and complex-generator-coordinate methods and to the orthogonality-condition model is discussed in detail.

The angular distribution of the depolarisation factor D( theta ) has been measured for the n-²H scattering at 2.45 MeV. The incident polarised neutron beam was produced from the ¹²C(d,n)¹³N reaction at 25 degrees lab. Two sets of phase-shifts between 0 and 3.27 MeV have been determined by fitting the cross sections in the frame of effective range approximation (ERA). The experimental results are compared with these phase-shift predictions.

The states of ⁴⁶Ti have been studied using the ⁴³Ca( alpha ,n gamma ) reaction. The level and decay scheme of ⁴⁶Ti was deduced from gamma - gamma coincidence, gamma -ray energy and intensity measurements. Spins are suggested on the basis of the gamma -ray angular distribution, supported by relative excitation functions. The ground-state band has been extended to spin 10⁺, and about 20 new states are observed. Some of these can be grouped into rotational-like bands based on the 3^- state at 3.059 MeV and other excited states.

Excitation functions for the reaction ⁵⁵Mn(p, gamma )⁵⁶Fe in the proton energy range 1660-1710 keV have been measured. Three relatively strong resonances at E_p=1678, 1687 and 1695 keV have been observed. It is found that the decay characteristics of the first two resonances are nearly identical, while those of the third are distinctly different. Angular distributions of gamma rays have been measured. Analysis of the angular distribution data leads to an assignment of J^pi =(2⁺, 3⁺) for the 1695 keV resonance and the most probable assignment of J^pi =4⁺ for the 1678 and 1687 keV resonances. The 1695 keV resonance in ⁵⁶Fe is identified as the isobaric analogue resonance (IAR) of the 340.9 keV state of ⁵⁶Mn. The 1678 and 1687 keV resonances are the fine-structure components of the IAR of the 335.5 keV state in ⁵⁶Mn.

Two isomeric gamma -rays have been observed in ¹⁰⁰Tc following the ¹⁰⁰Mo(p,n)¹⁰⁰Tc reaction at E_p=3.7 MeV. An isomeric level is identified at an excitation energy of 200.83+or-0.10 keV and its half-life is measured using a pulsed beam technique as 8.46+or-0.05 mu s. This isomeric state decays via a 28.6+or-0.4 keV gamma ray to the first excited state at 172.12+or-0.06 keV. A comparison of the predicted and observed Tc K X-ray intensities suggests that the 28 keV transition is pure E2 radiation.

The number of L X-rays of Pb emitted per alpha disintegration has been measured for the predominantly ground-state-ground-state alpha decay of ²⁰⁸Po using a high-resolution Si(Li) X-ray detector and a low-geometry alpha counter. The result of (2.3+or-0.2)*10^-4 L X-rays per alpha disintegration is, within the experimental uncertainty, equal to that for ²¹⁰Po, the only other case for which measurements have been made. The long-standing discrepancy between theory and experiment does not, therefore, appear to be due to some effect peculiar to the ²¹⁰Po decay.