Evidence for ρ-ω interference effect in π−p interactions at 3.9 GeV/c

In this paper we present evidence for a constructive interference effect between the 2π decays of the ω and the ϱo observed in the reaction π−p → pπ+π−π− at 3.9 GeV/c. From analysis of the π+π− mass spectrum, we obtain for the branching ratio Γ(ω → π+π−)/Γ(ω → π+π−π0) a lower limit of 1.1% at the 95% confidence level.