Measurements of ϱ - ω interference in the reaction πp → ππn at 15 GeV/c

In a study of the reaction π⁻p → π⁺π⁻n at 15 GeV/c we observe pronounced ?-ω interference effects between the transverse helicity states of the vector mesons. The relative phase of the interfering amplitudes is determined to be −1.40 ± 0.45 rad, and the branching ratio ω → 2π is found to be 2.1_−0.9^+2.8%.