Study of Reaction K⁻+p→Λ+η near Threshold

The cross section for the reaction K⁻+p→Λ+η was measured as a function of the incident K⁻ momentum in the vicinity of the reaction threshold. The excitation function for this reaction including earlier data confirms the existence of Λ (1670) with a mass and width of 1668 MeV/c² and 15 MeV/c² decaying into Λη with x_e1x_Λη=0.040. In addition, the behavior of the excitation function as well as the Λ angular distributions and polarization strongly suggest the existence of Λ (1690) with a mass and width of 1680 MeV/c² and 10 MeV/c² decaying into Λη with x_e1x_Λη=0.025.