Near-threshold production of a0(980) mesons in πN and NN collisions and a0-f0 mixing

AbstractWe consider near-threshold a0(980)-meson production in πN and NN collisions. An effective Lagrangian approach with one-pion exchange is applied to analyze different contributions to the cross section for different isospin channels. The Reggeon exchange mechanism is also evaluated for comparison. The results from πN reactions are used to calculate the contribution of the a0 meson to the cross sections and invariant $$K\bar K$$ mass distributions of the reactions $$pp \to pnK^ + \bar K^0 $$ and pp → ppK+K−. It is found that the experimental observation of a0+ mesons in the reaction $$pp \to pnK^ + \bar K^0 $$ is much more promising than the observation of a00 mesons in the reaction pp → ppK+K−. Effects of isospin violation in the reactions pN → da0, pd → 3He(3H)a0, and dd → 4Hea0, which are induced by a0(980)-f0(980) mixing, are also analyzed.