Theoretical analysis of Λ(1405) → (Σπ)0 mass spectra produced in p plus p → p plus Λ(1405) + K+ reactions

We formulated the Lambda(1405) (abbreviated as Lambda*) -> (Sigma pi)(0) invariant-mass spectra produced in p + p -> p + Lambda* + K+ reactions, in which both the incident channel for a quasibound K(-)p state and its decay process to (Sigma pi)(0) were taken into account realistically. We calculated M(Sigma pi) spectral shapes for various theoretical models for Lambda*. These asymmetric and skewed shapes were then compared with recent experimental data of HADES, yielding M(Lambda*) = 1405(-9)(+11) MeV/c(2) and Gamma = 62 +/- 10 MeV, where the interference effects of the (K) over barN-Sigma pi resonance with the I = 0 and 1 Sigma pi continuum are considered. The nearly isotropic proton distribution observed in DISTO and HADES is ascribed to a short collision length in the production of Lambda*, which justifies the high sticking mechanism of Lambda* and the participating proton into K(-)pp.