Mass and KΛ coupling of the N*(1535)

Abstract

Using a resonance isobar model and an effective Lagrangian approach, from recent BES results on J/ψ→p̄pη and ψ→p̄ K+Λ, we deduce the ratio between effective coupling constants of N*(1535) to KΛ and pη to be R gN*(1535)KΛ/ gN*(1535)pη=1.3±0.3. With the previous known value of gN*(1535)pη, the obtained new value of gN*(1535)KΛ is shown to reproduce recent pp→pK+Λ near-threshold cross section data as well. Taking into account this large N*KΛ coupling in the coupled channel Breit-Wigner formula for the N*(1535), its Breit-Wigner mass is found to be around 1400 MeV, much smaller than the previous value of about 1535 MeV obtained without including its coupling to KΛ. The implication on the nature of N*(1535) is discussed. © 2006 The American Physical Society.