Evidence for a scalar κ(900) resonance in (Formula Presented) scattering

Motivated by the (Formula presented) expansion, we study a simple model in which the (Formula presented) scattering amplitude is the sum of a current-algebra contact term and resonance pole exchanges. This phenomenological model is crossing symmetric and, when a putative light strange scalar meson κ is included, satisfies the unitarity bounds to well above 1 GeV. The model also features chiral dynamics, vector meson dominance and appropriate interference between the established (Formula presented) resonance and its predicted background. We briefly discuss the physical significance of the results and directions for further work. © 1998 The American Physical Society