Further evidence for the ${\Sigma }^{\ast }$ resonance with $J^P=1/2^{-}$ around 1380 MeV

Abstract

The unquenched quark models predict the new particle ${\Sigma }^{\ast }$ with spin parity $J^P=1/2^{-}$ and its mass is around the well established ${\Sigma }^{\ast }(1385)$ with $J^P=3/2^{+}$. Here by using the effective Lagrangian approach we study \kp\ reaction at the range of ${\Lambda }^{\ast }(1520)$ 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 ${\Sigma }^{\ast }(1385)$ with $J^P=3/2^{+}$, there is a strong evidence for the existence of the new resonance ${\Sigma }^{\ast }$ with $J^P=1/2^{-}$ around 1380 MeV. Higher statistic data on relevant reactions are needed to clarify the situation.

Comments: 15 pages, 40 figures