Study of Σ(1670) resonance production K-p interactions

Production of the Σ(1670) resonance in the reactions K-p → Λπ+π-, K-p → Σ0+π+0π-, K-p → Σ-π+π0, and K-p → Σ±π± π+π- for K- beam momenta around 2.1 and 2.6 GeV/c in data from the Bevatron 72-inch hydrogen bubble chamber is analyzed. Large variations in the ratio of the cross section for the reaction K-p → Σ+(1670)π- → Λ(1405)π+π- → Σ±π+π- to the cross section for the reaction K- → Σ+ 670)π- → (Σπ)+π- as a function of the Σ(1670) production angle. This variation is interpreted as strong evidence that more than one resonance contributes to the Σ(1670) enhancement. Analysis of the production angular distributions of the three Σ(1670) decay modes Λpi' Σπ, and Λ(1405)π shows that the results are consistent with the existence of a Σ(1670) resonance that decays mainly into Λ(1405)π and another that decays mainly into Λπ and Σπ. Other production experiments are seen to be consistent with these results. The Λπ/Σπ branching ratio is estimated to be 0.8 ± 0.1. The data are also consisent with the existence of two interfering Σ(1670) resonances with approximately equal masses and widths.