An improved study of the kappa resonance and the non-exotic $s$ wave $\pi K$ scatterings up to $\sqrt{s}=2.1$GeV of LASS data

摘要

We point out that the dispersion relation for the left hand cut integralpresented in one of our previous paper (Nucl. Phys. {\bf A}733(2004)235) isactually free of subtraction constant, even for unequal mass elasticscatterings. A new fit to the LASS data~\cite{Aston} is performed and firmevidence for the existence of $\kappa$ pole is found. The correct use ofanalyticity also put strong constraints on threshold parameters -- which arefound to be in good agreement with those obtained from chiral theories. We alsodetermined the pole parameters of $K_0^*(1430)$ on the second sheet, andreconfirm the existence of $K_0^*(1950)$ on the third sheet. We stress that theLASS data do not require them to have the twin pole structure of a typicalBreit--Wigner resonance.