Diffraction dissociation in elementary particle reactions

Abstract

We extend the results for asymptotic s-channel vertices in terms of covariant couplings to high spin fermion and boson production. The formalism is applied to diffraction, considered as proceeding by pomeron exchange. It is found that the pomeron couples in a similar manner to a vector object. In particular the hypothesis is made that the pomeron coupling to the N → N* vertex is XB. This is supported by fits to the N → N* (31/2, 1520; 51/2(^+) 1688) data. The behaviour of the pomeron as a vector object is understood in the quark model and it is seen that most of the fernion data can be described in an SU(6)w quark model. The breakdown of the approach for boson diffraction dissociation is noted, as spin orbit terms are needed to reproduce the data. A relativistic quark model is presented for mesons with spin 1/2 quarks which is closely related to the non-relativistic harmonic oscillator model. The conventional quark model spectrum is reproduced with particles lying on straight Regge trajectories, although the masses predicted for the PC = + | states are large. The most interesting feature of the wave-functions is the natural inclusion of spin-orbit terms which is suggestive of the "current'' quark approach. The comparison of the model predictions with the data is encouraging and they include meson decay widths for emission of a pseudoscalar or a photon. Diffraction dissociation is also considered in- the model and the inclusion of spin-orbit interaction rectifies some of the difficulties of the SU(o) model applied to meson dissociation.