abstract

A solution of Einstein field equations has been obtained fort piano symmetric space-time filled with perfect fluid. Certain physical and geometrical properties of the model have been examined.

abstract

The equations connecting the Hamiltonian of a physical system under consideration with the projection operator onto a subspace of unstable particles are given. Solutions of these equations are found for the Lee model.

abstract

The magnetic moments of the U and D quarks are calculated using various spin flavor wave functions assuming that the subquarks are rishons. The interpretation that color is a spin flavor permutation symmetry leads to a correct prediction for \(\mu _{\rm U}/\mu _{\rm D}\). The possibility that the \(T\), \(V\) rishons form a flavor doublet is also exploited and the resulting values for \(\mu _{\rm U}/\mu _{\rm D}\) using various spin flavor combinations are calculated.

abstract

The production of K\(^0_{\rm S}\), \(\Lambda ^0\), and \({\overline \Lambda }\)\(^0\) in \(\pi \)–d interactions at 21 GeV/\(c\) is investigated. Cross sections for single neutral strange particles and their pairs are determined both inclusively and as functions of the charged multiplicity. Inclusive, single particle distributions show the same general features as in \(\pi ^{\pm }\)p interactions (in hydrogen). The effects of double scattering are estimated. The neutral strange particle production in \(\pi ^-\)n collisions has been extracted from deuterium data and compared with isospin symmetric \(\pi ^+\)p reaction (in hydrogen) at similar energies. The polarization of \(\Lambda ^0\) has been found negligible except for \(\Lambda ^0\) produced in the backward hemisphere at large \(p_{\rm t}\). The Feynman x distributions of neutral strange particles bath in beam and target fragmentation regions arc compared with the quark counting rules predictions.

abstract

I review present experimental and theoretical status of electromagnetic decays of light mesons. Special attention is paid to single-photon decays of charged resonances, and to recent applications of the Primakoff technique to measure such processes. New data on radiative decays of pseudoscalar, vector, axial and tensor mesons are compared with several theoretical calculations involving quark models, unitary symmetry relations, and an effective Lagrangian approach. Vector Meson Dominance ideas, as applied to meson spectroscopy, are discussed in detail. Also, the electromagnetic properties of the A\(_1\) meson are examined in the context of resonance parameters observed in diffractive production and \(\tau \)-lepton decays. Finally, I emphasize the importance of radiative processes in searching for glueball and hybrid states of matter.