Resonance production and decays

Abstract

This thesis deals with some phenomena connected with resonance production or formation, at low energies, and/or their subsequent decay. It is subdivided into two almost independent parts: The first part (chapter II) is concerned with W/M production in π – N scattering, and a possible charge asymmetry in their decay, we explicitly calculate the asymmetry for the reaction π (^+) p → π (^+) π (^-) π (^o) Ϫ (^++) caused by interference of w production with uncorrelated 3N production. Assuming C-invariance for the W-decay, we find that interference terms with a coherent 3N background cannot explain the whole of the asymmetry experimentally observed. The second part (chapters III and IV), deals with K-N scattering. In chapter III, examining the possible Lorentz-invariant, parity-conserving couplings of the t-channel exchanges to the external particles, and afterwards reggeizing them, we are able to construct simple models for the processes KN → KD and KN → K (^o) N, which are capable of giving a satisfactory fit to the data over a wide range of energies. For completeness, a simple model for elastic KN scattering is also presented. In chapter IV we use the results of chapter III as input into a K-matrix machinery, from which we get a unitary isoscalar KN scattering model, analytically solvable, which reproduces several basic features of recent phase shift analyses, in particular a wide J (^P) exotic resonance Z (_o) (1780)