abstract

The possibility that the spin systems of b-universality and of the additive quark model coincide, as suggested by previous analyses [1, 2], is investigated. A comparison of the predictions with the data for the processes \(0^-\frac {1}{2}^+ \to 1^-\frac {3}{2}^+\) shows very good agreement with this hypothesis in both helicity and Gottfried-Jackson frames.

abstract

Using an uncorrelated cluster emission model with a superposition of coherent states to describe non-diffractive processes, the diffractive production is estimated by means of shadow calculations, the results of which are shown to be linear as regards the probability distributions. The model describes fairly well the absolute magnitudes of cross-sections as well as the multiplicity distribution.

abstract

The rearrangement effects in asymmetric nuclear matter are investigated within the framework of the lowest order Brueckner theory with the Reid soft core nucleon–nucleon interaction. The accuracy of the single density approximation, which has been used previously in several investigations of the properties of asymmetric nuclear matter, is studied in the case of the symmetry energy and of the individual elements of the reaction matrix.

abstract

We present a general discussion of many-body densities in nuclei, including two-body and one-body densities. The short-range part of the two-body density is calculated in the independent-pair approximation for nuclear matter, and we study effects of Pauli correlations, correlations induced by a hard-core, and correlations coming from the Moszkowski–Scott interaction. These model correlation functions are used as a basis for a comparison of two classes of measurements of the two-body density where one has relatively well-known probes: inelastic sum rules (electron and nucleon) and elastic proton-nucleus scattering at high energies. We carry out calculations for \(^{12}\)C and \(^{16}\)O and emphasize that the low-momentum-transfer part of the sum rules depends critically on the finite extent of the nucleus and the low-lying collective modes. The most promising of these tools for measuring short-range correlations appears to be high-momentum transfer inelastic nucleon sum rules, although there are problems associated with the mesonic degrees of freedom in the nucleus. Other possibilities for measuring two-body densities are discussed very briefly.

abstract

It is pointed out that multiplicity distributions associated with a large \(p_{\perp }\) trigger can provide useful information on the underlying jet structure. In particular, in the presently investigated \(s\) and \(p_{\perp }\) range, the \(\overline {n}/D\) ratio is expected to be markedly larger than Wróblewski’s value (\(\sim 1.9\)). Study of the \(p_{\perp }\) and \(s\) dependence of this ratio can discriminate between Poisson-like versus KNO-like behaviour of the multiplicity distribution in the jet itself and separately in the remaining low \(p_{\perp }\) background.

abstract

A method of practically solving of nuclear reaction problems on a single-particle basis is proposed within the framework of the microscopic approach. The method ensures the fulfilment of Pauli’s principle and translational invariance requirements.