The Role of Lambda(1405) in Kaon-Proton Interactions

Abstract

S-wave $K^{-}p$ scattering into various channels near threshold are analyzed in heavy-baryon chiral perturbation theory with $\Lambda (1405)$ introduced as an independent field. This is the approach that predicted the critical density $2<={\rho }_c/{\rho }_0<=3$ for negatively charged kaon condensation. We show that chiral perturbation expansion treating the $\Lambda (1405)$ as elementary is consistent with {\it all} threshold data including a double-charge-exchange process suppressed at leading order of chiral expansion in the absence of the $\Lambda (1405)$. We also discuss S-wave $K^{+}p$ scattering phase shifts at low energy.

Comments: 12 pages, epsfig.sty, 1 figure (uuencoded)