PI-P-]PI-PIOP REACTION AT 2.77 GEV/C FOR LOW MOMENTUM TRANSFERS TO PROTON

The reaction π-p→π-π0p produced by 2.77-GeV/c pions has been studied for low squared four-momentum transfers to the proton (Δ2<~13μ2). A selection based on a fast premeasurement method has allowed the accumulation of high statistics (7666 events) and a detailed study of the ρ- properties. In particular, the ρ- mass and width are determined as a function of Δ2, showing essentially no variation of these parameters in the whole Δ2 range. On the other hand, the mass and width values deduced from the mass spectra (ωr=773±2 MeV, Γr=150±5 MeV) differ from the corresponding values for the resonant P wave (ωr=755±5 MeV, Γr=110±9 MeV) obtained by extrapolation to the pion pole, following the Chew-Low method. Essential results on the π-π0 elastic cross section are summarized. The sensitivity of the determination of the ρ- production and decay parameters to various mass and Δ2 cuts is shown. © 1968 The American Physical Society.