Possible evidence for the Sigma* resonance with J(P)=1/2(-) around 1380 MeV

The unquenched quark models predict the new particle Sigma* with spin-parity J(P) = 1/2(-) and its mass is around the well-established Sigma* (1385) with J(P) = 3/2(+). Here, by using the effective Lagrangian approach, we study K- p -> Lambda pi(-) pi(+) reaction at the range of Lambda* (1520) peak, comparing the resulting total cross section, and pi(+) pi(-), Lambda pi(+), Lambda pi(-) invariant squared mass distributions for various incident K- momenta, as well as the production angular distribution of the Lambda with the data from the Lawrence Berkeley Laboratory 25-inch hydrogen bubble chamber; we find that, apart from the existing resonance Sigma* (1385) with J(P) = 3/2(+), there is evidence for possible existence of the new resonance Sigma* with J(P) = 1/2(-) around 1380 MeV. Higher statistic data on relevant reactions are needed to clarify the situation.