Experimental results on 8 GeV/c π−-p interactions with two, three and four pions

π−-p interactions at 8 GeV/c have been produced in a liquid-hydrogen target placed in 1 m heavy liquid bubble chamber of the Ecole Polytechnique. The following resonances have been observed:N 3 2/* 3 2/+ + and ρ0 in the π+π−π−p channel, a small proportion of ω0 in the π+π−π0n channel; and ρ0 in the π+π−π+π−n channel. In particular in three-charged-pion production, there is no evidence for A1 and A2 states and quasi-two-body final states are very rare. The Deck-model predictions, without nuclear absorption and ρ-ρ symmetrization, are in fair agreement with π+π−π− mass andΔ ρ 2 experimental distributions; however the angular predictions do not fit our data well. The total and differential cross-sections are given for each channel; for all reactions, the 4-momentum transfer distribution shows a slope comparable to that for elastic scattering.