ISSN - 00319007, EISSN - 10797114, Physical Review Letters, 2012, vol. 108, p. -
Spin-parity analysis of pp̄ mass threshold structure in J/ψ and ψ(3686) radiative decays
A partial wave analysis of the pp̄ mass-threshold enhancement in the reaction J/ψ→γpp̄ is used to determine its JPC quantum numbers to be 0 -+, its peak mass to be below threshold at M=1832-5+19(stat)-17+18(syst)±19(model)MeV/c2, and its total width to be Γ<76MeV/c2 at the 90% C.L. The product of branching ratios is measured to be BR[J/ψ→γX(pp̄)]BR[X(pp̄)→pp̄]=[9.0-1. 1+0.4(stat)-5.0+1.5(syst)±2.3(model)]×10 -5. A similar analysis performed on ψ(3686)→γpp̄ decays shows, for the first time, the presence of a corresponding enhancement with a production rate relative to that for J/ψ decays of R=[5.08-0.45+0.71(stat)-3.58+0.67(syst) ±0.12(model)]%. © 2012 American Physical Society.