An update on the Kappa

Abstract

New Focus data on Dplus -> Kminus piplus piminus are fitted to the kappa, together with earlier data from LASS, E791 and BES 2. There is a clear low mass K-pi peak due to the kappa pole. Inclusion of the I=3/2 K-pi amplitude gives only a marginal improvement to the fit and almost no change to the kappa peak. An improved formula for the kappa gives a better fit than that used earlier. The kappa pole moves to 663 +- 8(stat) +- 34(syst) -i[329 +- 5(stat) +- 22(syst)] MeV. The K0(1430) pole is at 1427 +- 4(stat) +- 13(stat) -i[135 +- 5(stat) +- 20(syst)] MeV.