A possible interpretation of $Λ$ baryon spectrum with pentaquark components

Abstract

The Λ baryon spectrum is studied within the SU(3) flavor symmetry in a constituent quark model. We found that it is rather difficult to accommodate some negative-parity Λ resonances as single q 2 s (q = u, d quarks) states in the conventional three-quark picture. The ground q 3 sq pentaquark mass spectrum is evaluated and a possible interpretation is proposed in the work: the observed Λ(1405)1/2 − , Λ(1670)1/2 − and Λ(1800)1/2 − are three-state mixtures of two p-wave q 2 s states and one ground q 3 sq pentaquark state, so are the Λ(1520)3/2 − , Λ(1690)3/2 − and Λ(2050)3/2 − resonances.