The reaction antipp→antipπ-π+p at 25 and 40 GeV/c

The reaction antipp→antipπ-π+p has been studied at 25 and 40 GeV/c at the Serpukhov proton synchroton using the CERN-IHEP spectrometer. The differential cross section has been determined as a function of four-momentum transfer to the proton (0.05-0.30 (GeV/c)2) and antipππ mass (up to 2.2 and 2.6 GeV/c2). At both energies there is a broad low-mass maximum with an enchancement at 1.6-1.8 GeV/c2. The cross section in a given mass band falls rapidly with mod(t), with an exponential slope that decreases with increasing mass. In both the background and the 1.7 GeV/c2 peak there is a strong antiΔ--π+ component. Possible spin-parity (Jsup(P)) contributions to it are discussed. Throughout the range 1.5-2.2GeV there is at least one state of J>=3/2 and there is interference between states of opposite P, mod(ΔJ)<= 1. At the peak there is a J>=5/2 component. There are striking parallels between this reaction and the boson reactions π-p→π-π-π+p and K-→K-π-π+p. (Auth.)