Analysis of the new Crystal Ball data on reaction with beam momenta of

摘要

The Crystal Ball Collaboration has recently reported the differential crosssections and $Lambda$ polarization for the reaction $K^-pightarrowpi^0Lambda$ using an incident $K^-$ beam with momenta between 514 and 750MeV/$c$. We make a partial wave analysis for this process with an effectiveLagrangian approach and study the properties of some $Sigma$ resonances aroundthis energy range. With the inclusion of the 4-star resonances $Sigma(1189)$,$Sigma^*(1385)$, $Sigma(1670){3over 2}^-$, $Sigma(1775){5over 2}^-$, aswell as a $Sigma(1635){1over 2}^+$, which is compatible with the 3-star$Sigma(1660){1over 2}^+$ in PDG, our results can well reproduce theexperimental data. The parameters on the $Sigma$ resonances and relatedcouplings are studied.