Resonances in the System of Pi+Pi- -- Mesons from the Reaction np->npPi+Pi- at Pn=5.20GeV/c: Search, Results of Direct Observations, Interpretation

Abstract

Ten resonances were found in the mass spectrum of pi+pi- -system from the reaction np->nppi+pi- in np-interactions at Pn=5.20 GeV/c in the 1-m HBC of LHE JINR by using the criterion cos(teta)[c.m.c.] p>0. Such effects were not found in pi-pi0 - combinations from the reaction np->pppi-pi0. Therefore, it is necessary to attribute the value of isotopic spin I = 0 to the resonances found in the mass spectrum of the pi+pi- -system. The spin was estimated for the most statistically provided resonances. We determine with a high degree of confidence that J = 0 for the resonances at MR = 757 MeV/c^2 and MR = 418 MeV/c^2. Therefore, it can be affirmed that at least 3 states with quantum numbers of sigma0-meson 0+(0++) have been found at masses of 418, 511 and 757 MeV/c^2. The fact low-mass sigma0-mesons are glueballs is one of the possible interpretations. The comparison with the data of other papers has also been made. The investigation has been performed at the Veksler and Baldin Laboratory of High Energies,JINR.