Evidence for a new $Σ^{*}$ resonance with $J^P=1/2^-$ in the old data of $K^-p\toΛπ^+π^-$ reaction

Abstract

Distinctive patterns are predicted by quenched quark models and unquenched quark models for the lowest SU(3) baryon nonet with spin parity $J^P=1/2^-$. While the quenched quark models predict the lowest $1/2^-$ $Σ^*$ resonance to be above 1600 MeV, the unquenched quark models predict it to be around $Σ^*(1385)$ energy. Here we re-examine some old data of the $\kp \to \la$ reaction and find that besides the well established $Σ^{*}(1385)$ with $J^P=3/2^+$, there is indeed some evidence for the possible existence of a new $Σ^{*}$ resonance with $J^P=1/2^-$ around the same mass but with broader decay width. Higher statistic data on relevant reactions are needed to clarify the situation.