Table of contents

A spin gauge theory model using the Clifford algebra C_4,7 gives, without using the Higgs-Kibble mechanism, the salient features of the standard model plus appropriate gravitational Lagrangian terms. Uniform normalization of particle Lagrangian terms produces a formula relating all fermion masses to the W mass. For three families, neglecting mixing, the mass formula gives the top quark mass as 151.7 GeV. The inclusion of family mixing is expected to change this value only by the order of 0.1 GeV.

The nuclear medium effect on the kaon dispersion relation is calculated using a model-independent method. It is found that the dominant contribution comes from the nucleons. In particular, different modifications are obtained for K⁺ and K^-. This difference leads to a large change in the ratio of K⁺ and K^- abundances.

Observations of Vel X-1 were made in February 1991 using the University of Durham Mark III and IV VHE gamma-ray telescopes at Narrabri, New South Wales, Australia. The complete data-set shows evidence for weak but apparently constant periodicity at the X-ray pulsar period with a signal strength compatible with the authors' earlier measurements. In addition, on two occasions (February 13 and February 22 1991) they have evidence for short (1800 s) outbursts of emission of gamma rays modulated with the pulsar period. These outbursts occur at the same orbital phase (0.68), and the periodic effects noted during the outbursts have probabilities of change occurrence of 5.9*10^-4 and 4.4*10^-7.

It is shown how the glueball spectrum can be obtained from the Bethe-Salpeter equation using nonperturbative approximations. The masses are estimated to be (3.5+or-0.4) Lambda _QCD for the 0⁺ and 2⁺ glueballs and (2.8+or-0.3) Lambda _QCD for the 1^- glueball.

A new method of neutron electric dipole moment (EDM) searching is proposed. It is based on the spin dependence of the Pendellosung phase of a neutron diffracted by a noncentrosymmetric crystal. A two-crystal set-up is proposed and analysed to get the most luminosity possible. A strong interplanar electric field of the crystal and a sufficiently long time for the neutron passage through the crystals for Bragg angles close to pi /2 makes it possible to exceed the sensitivity achieved with the ultra cold neutron method.

The general structure of the solitons with baryon number 1-12 has been investigated in the framework of the variational approach to the Skyrme model. Some of the solitons have a toroidal structure and some of them are much more complicated. The masses of the obtained solitons are also given. After quantization these solitons can be interpreted as nuclear states. Some of them could have isomer states which differ by their form.

The authors have previously formulated a general translationally invariant version of the coupled cluster theory. The authors investigate the linearized approximation referred to as the second-order translationally invariant cluster method. In particular, they algebraically formulate and numerically solve this method at the optimal Euler-Lagrange level for finite bosonic systems. The method proves to be highly superior to the standard configuration-interaction calculations of the shell-model type, and confirms the validity of the Gaussian geminal expansion of the two-body cluster C₂.

The isotope shifts and hyperfine splittings of atomic optical lines in ^132,134-143Nd ( lambda =588.79 nm), ^138-145Sm ( lambda =600.42 nm) and ^138-145Eu ( lambda =576.52 nm) have been measured using resonance ionization spectroscopy. The magnetic dipole and electric quadrupole moments of the odd Nd and Sm isotopes and the changes in mean square charge radii delta (r²) for all isotopes in question have been derived. A shell effect and a strong Z-dependence in the isotopic behaviour of delta (r²) at N<82 have been observed. The experimental data have been analysed in the framework of the Hartree-Fock method.

Inelastic electron scattering measurements up to 1.5 fm^-1 of strong M1 transitions to the 10.900 MeV, 11.446 MeV and 12.330 MeV states in ²⁸Si, which form the bulk of the ²⁸Si M1 isovector giant resonance, have revealed striking differences in their transition form factors, and have allowed information on the configurations contributing to each transition to be deduced. Full 2s-1d shell model calculations have also shown large differences in the form factors of the lowest J^pi =1⁺, T=1 states, but do not agree, in detail, with the experimental data.

High-spin states of ¹⁶⁵W and ¹⁶⁶W were studied using the ¹⁰⁶Pd(⁶³Cu, p3n) and ¹⁰⁶Pd(⁶³Cu, p2n) reactions, respectively. Gamma rays in ¹⁶⁵W were identified for the first time using the gamma -ray detector array POLYTESSA and the Daresbury recoil separator. Level schemes for ¹⁶⁵W and ¹⁶⁶W were constructed from the gamma - gamma coincidence data and angular correlation data from the POLYTESSA and TESSA3 arrays. In ¹⁶⁶W the yrast band is established up to 30⁺ (32⁺), as well as two side bands up to 22^- (28^-) and 23^- (29^-). In ¹⁶⁵W the yrast band is established up to 45/2⁺ and two side bands up to 55/2^- (59/2^-) and 53/2^-. The rotational structures and band crossings observed are interpreted within the framework of the cranked shell model in terms of quasiparticle excitations. The systematics of the second i_13/2 neutron alignment in the N=91 and 92 isotones are discussed.

The authors describe an L² formalism for the continuum spectrum of coupled collective states in light nuclei. In particular, they consider the application to the monopole and quadrupole modes in ⁴He. They compute the phase shifts and perform an extensive analysis of the resonance wavefunctions.

Cluster decays of some heavy and super-heavy, formed in heavy-ion 'cold fusion' reactions, are studied within a preformed cluster decay model. The cold super-asymmetric fission of these nuclei is also investigated. Some of the calculated exotic cluster decays from the ground to ground or excited to excited states are found to have half-liver T₁2/<10²⁵ s, which are measurable with presently available experimental techniques. If such decays of the compound systems are observed as the long lived, super asymmetric, spontaneous fission activity, or simply as the cold fission process, it could give rise to some other new, heavy and super-heavy nuclei. Shell stabilization effects due to both the spherical and deformed shell closures are found to be responsible for selecting both the favourable cold fusion reactions as well as the most probable cluster decays.

For pt.III see ibid., vol.18, p.553 (1992). The world's data on cosmic rays above 10¹⁹ eV have been revisited and a more extended analysis made than hitherto. The analysis, which relates to a study of anisotropies on a range of angular scales, and a reanalysis of individual shower characteristics in the Sydney experiment, strengthens the view that the particle beam contains a range of masses and that some of the particles are derived from galactic sources.

A hypothesis is suggested such that the anomalous TeV muon and hadron events detected from the direction of Cyg X-3 are initiated by extremely high-energy primaries (gamma-rays and/or neutrons). This hypothesis requires the existence of massive particles with M_x approximately 1 TeV and lifetime tau _X approximately 10^-6 s, which are created at interactions of primaries in the atmosphere, then effectively cascade and decay, producing high-energy muons and hadrons at large angles.

The authors point out the possible correlation between inelasticity and cross section emerging from the analysis of different cosmic ray experiments. This correlation could be used for the determination of the actual value and of the energy dependence of inelasticity in cosmic ray experiments. This energy dependence is discussed for a representative sample of theoretical models of multiparticle production. Present cosmic ray data are compatible with a decrease of inelasticity with energy, similar to that found in accelerator data.

For original paper see Phys. Rev. Lett., vol.67, p.2630 (1991). The authors compare their analysis of neutron decay observables with a recently reported tritium half-life measurement to investigate the insight they may provide into the admixture of a 17 keV c^-2 neutrino in the electron flavour.