Resonance model of pi Delta to YK for kaon production in heavy-ion collisions

Abstract

The elementary production cross sections pi Delta to YK (Y= Sigma , Lambda ) and pi N to YK are needed to describe kaon production in heavy-ion collisions. The pi N to YK reactions were studied previously by a resonance model. The model can explain quite well the experimental data obtained by us. In this article, the total cross sections pi Delta to YK at intermediate energies (from the kaon production threshold to 3 GeV of pi Delta centre-of-mass energy) are calculated for the first time using the same resonance model. The resonances, N(1710)I(JP)= 1/2 ( 1/2 +) and N(1720) 1/2 (3/2+) for the pi Delta to Sigma K reactions, and N(1650) 1/2 ( 1/2 -) N(1710) 1/2 ( 1/2 +) and N(1720) 1/2 (3/2+) for the pi Delta to Lambda K reactions are taken into account coherently as the intermediate states in the calculations. Also, t-channel K*(892) 1/2 (1-) vector-meson exchange is included. The results show that K*(892) exchange is negligible for the pi Delta to Sigma K reactions, whereas this meson does not contribute to the pi Delta to Lambda K reactions. Furthermore, the pi Delta to YK contributions to kaon production in heavy-ion collisions are not only non-negligible but also very different from the pi N to YK reactions. An argument valid for pi N to YK cannot be extended to pi Delta to YK reactions. Therefore, cross sections for pi Delta to YK correctly including the different isospins must be calculated for inclusion in simulation codes for kaon production in heavy-ion collisions, where no experimental data are available. Parametrizations of the total cross sections pi Delta to YK for kaon production in heavy-ion collisions are given based on this work.