Coherent Hypernucleus Production in Antiproton-Nucleus Annihilation Reactions as a Probe for $\kappa$ meson Exchange

Abstract

The hypernucleus production reaction $\bar p + {}^AZ \to {}^A_\Lambda(Z-1) + \bar{\Lambda}$ in the beam momentum range 1.5-20 GeV/c is addressed theoretically as a coherent process. The calculations are based on a covariant $t$-channel meson exchange model for the elementary $\bar p p \to \bar\Lambda \Lambda$ annihilation amplitude with parameters fixed by comparison with empirical data. Besides pseudo-scalar $K$ and vector $K^*$ mesons we also account for correlated $\pi K$ contributions, modelled by the scalar $K^*_0(800)$ or $\kappa$ meson. Initial and final state nuclear interactions are taken into account in eikonal approximation. The bound baryon wave functions are obtained self-consistently in a covariant mean-field approach. It is shown that the hypernucleus production cross sections populating discrete states are dominated by the vector and scalar interaction channels. The pronounced sensitivity on the scalar $\kappa$ meson exchange contributions indicates that these reactions are well suited as a probe for correlated $\pi K$ exchange in the scalar $\kappa/K^*_0$ interaction channel.