EVIDENCE FOR THE DOMINANCE OF AN IGJPC=0+0++ RESONANCE IN (P)OVER-BARN-]2-PI+3-PI- ANNIHILATION AT REST

The reanalysis of 1496 pnBAR --> 2pi+ 3pi- annihilations at rest of the Rome-Syracuse collaboration has shown that this reaction is dominated by the production of a 4pi resonance with M = 1386 MeV/c2, GAMMA = 310 MeV/c2 and quantum numbers I(G)J(PC) = 0+0++. This result is in disagreement with a previous analysis, which, assuming rhorho decay, found preference for J(P) = 2+. The name proposed for the resonance is S0(1390). The dominant decays of this resonance are into rhorho and sigmasigma, sigma being the I = 0 S-wave 2pi interaction. The upper limit for other decays is estimated to be 20%. The rho0rho0 - sigmasigma interference reproduces the distributions of the like pion combinations 2pi+, 2pi- and 3pi-. This indicates that the interference between resonance and daughters could be one of the dynamical mechanisms which generate the Bose-Einstein correlation. Furthermore, an evaluation of the five-prong frequencies is reported. Using these values, the total frequency of the annihilation pnBAR --> S0(1390)pi- is estimated to be between 15% and 20%.