Ξ− hyperon and hypernuclear production in the (K−,K+) reaction on nucleon and nuclei in a field theoretical model

摘要

We investigate the production of a cascade hyperon ($Xi$) and bound $Xi^-$hypernuclei in the $(K^-,K^+)$ reaction on proton and nuclear targets,respectively, within a covariant effective Lagrangian model. The $K^+Xi^-$production vertex is described by excitation, propagation and decay of$Lambda$ and $Sigma$ resonance states in the initial collision of a $K^-$meson with a free or bound proton in the incident channel. The parameters ofthe resonance vertices are taken from previous studies and SU(3) symmetryconsiderations. The model is able to provide a good description of theavailable data on total and differential cross sections for the $p(K^-,K^+)Xi^-$ reaction. The same mechanism was used to describe the hypernuclearproduction reactions $^{12}$C$(K^-,K^+)^{12}{/!/!/!_{/Xi^-}}$Be and$^{28}$Si$(K^-,K^+)^{28}{/!/!/!_{Xi^-}}$Mg, where $Xi$ bound state spinorscalculated within a phenomenological model have been employed. Both theelementary and hypernuclear production cross sections are dominated by thecontributions from the $Lambda$(1520) intermediate resonant state. The beammomentum dependence of the $0^circ$ differential cross sections for theformation of the $Xi$ hypernuclei is found to be remarkably different fromwhat has been observed previously in the impulse approximation modelcalculations