K−p→Σ0π0reaction at low energies in a chiral quark model

Abstract

A chiral quark-model approach is extended to the study of the (K) over bar N scattering at low energies. The process K- p -> Sigma(0)pi(0) at P-K less than or similar to 800 MeV/c (i.e., the center-of-mass energy W less than or similar to 1.7 GeV) is investigated. This approach successfully describes the differential cross sections and total cross section with the roles of the low-lying Lambda resonances in n = 1 shells clarified. The Lambda(1405)S-01 dominates the reactions over the energy region considered here. Around P-K similar or equal to 400 MeV/c, the Lambda(1520)D-03 is responsible for a strong resonant peak in the cross section. The Lambda(1670)S-01 has obvious contributions around P-K = 750 MeV/c, while the contribution of Lambda(1690)D-03 is less important in this energy region. The nonresonant background contributions, i.e., u channel and t channel, also play important roles in the explanation of the angular distributions due to amplitude interferences. The u channel turns out to have significant destructive interferences with the Lambda(1405)S-01 at the forward angles. In contrast, the t-channel K* exchange has a constructive interference at the forward angles, whereas it suppresses the cross sections slightly at the backward angles. In the t channel, the K* exchange is more dominant than the kappa exchange. Our analysis suggests that configuration mixing exists within the Lambda(1405)S-01 and Lambda(1670)S-01 and results in admixtures of the [70, (2)1, 1/2] and [70, (2)8, 1/2] configurations. The Lambda(1405)S-01 is dominated by [70, (2)1, 1/2], and Lambda(1670)S-01 by [70, (2)8, 1/2]. The mixing angle is also determined. The Lambda(1520)D-03 and Lambda(1690)D-03 are assigned as [70, (2)1, 3/2] and [70, (2)8, 3/2], respectively.