Remarks on the phenomenological analysis of resonances

Abstract

Some remarks are made concerning various aspects of the analysis of resonances produced in multi-particle final states resulting from high-energy collisions. The shape and position of a resonance are discussed by means of the connection between production cross-sections for stable and unstable particles, and a numerical example ofN* as seen in KN → KN* at different energies is given. The relation between the present description of the resonant effects and others (Watson’s finalstate interaction formula and the one-meson-exchange model of Chew and Low) is examined. Off-the-mass-shell corrections to the one-meson-exchange model are obtained in a relatively simple way. The bearing of the decay angular correlations on the production mechanism is explored ; co-ordinate axes appropriate for the peripheral model are specified; the equivalence of the azimuthal angular distribution and the Treiman-Yang distribution is established. Angular correlations are given for the decay of boson resonances (J=l, 2) resulting from definite spin and parity states in thet-channel. Some remarks are made about the inclusion of nonresonant contributions when there is a mixture of pseudoscalar and vector exchange.