Coupling strength of the N*(1535)S₁₁ to the K ⁺Λ channel

The N*(1535)S₁₁ coupling strength to the K ⁺Λ channel, g_N*(1535)ΛK⁺, is extracted from the latest and largest K⁺Λ photoproduction database by using an isobar model. It is found that the coupling is small. In terms of the coupling ratio the best result is R≡|g _N*(1535)ΛK⁺/g _N*(1535)ηp|=0.460±0.172, much smaller than that obtained from the isobar analysis of the J/ψ decays, i.e., 1.3±0.3, but consistent with the results of the unitary chiral approach of the same decay processes as well as the partial wave analysis of kaon photoproduction, i.e., R=0.5∼0.7. The different results of R found here and in the literature to date suggest that a more solid definition of the coupling constant, especially in the case of the N*(1535)S₁₁ state, is urgently required before a fair comparison can be made.