SEARCH FOR EXOTIC BARYON RESONANCES IN THE BARYON-EXCHANGE REACTION PI+P-]PF-PI+PI+PI- AT 4 GEV/C

A search for exotic baryon resonances with I = 5/2 decaying into p-pi+ pi+, predicted by analyses of superconvergent sum rules, was carried out in the reaction pi+ p --> p(f)-pi+ pi+ pi- (where p(f) is a fast, forward-emitted proton) at 4 GeV/c. On analyzing the mass and angular spectra of the system p-pi+ pi+ no signal from exotic resonances was found in the region M(p)-pi+ pi+ < 2 GeV/c2. The limit obtained here on the exotic-resonance production cross section is significantly smaller than the cross sections at which exotic baryons are observed in other experiments carried out with lower statistics. A comparison of our experimental results with the production cross sections predicted in the literature for the exotic baryon E55 allows us to exclude at the 95% confidence level the mass region M(E) < 1.53 GeV/c2 and widths GAMMA-E < 170 MeV/c2 for the E55.