K-p→Σ0π0 reaction at low energies in a chiral quark model

A chiral quark-model approach is extended to the study of the Kmacr N scattering at low energies. The process K^-p→Σ⁰π⁰ at P_K≲800 MeV/c (i.e., the center-of-mass energy W≲1.7 GeV) is investigated. This approach successfully describes the differential cross sections and total cross section with the roles of the low-lying Λ resonances in n=1 shells clarified. The Λ(1405)S₀₁ dominates the reactions over the energy region considered here. Around P_K≃400 MeV/c, the Λ(1520)D₀₃ is responsible for a strong resonant peak in the cross section. The Λ(1670)S₀₁ has obvious contributions around P_K=750 MeV/c, while the contribution of Λ(1690)D₀₃ 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 Λ(1405)S₀₁ 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 κ exchange. Our analysis suggests that configuration mixing exists within the Λ(1405)S₀₁ and Λ(1670)S₀₁ and results in admixtures of the [70,²1,1/2] and [70,²8,1/2] configurations. The Λ(1405)S₀₁ is dominated by [70,²1,1/2], and Λ(1670)S₀₁ by [70,²8,1/2]. The mixing angle is also determined. The Λ(1520)D₀₃ and Λ(1690)D₀₃ are assigned as [70,²1,3/2] and [70,²8,3/2], respectively.