Study of the near-threshold ω mass enhancement in doubly OZI-suppressed J/ψ→γω decays

Abstract

A 2:25 x 10(8) J/psi event sample accumulated with the BESIII detector is used to study the doubly Okubo-Zweig-Iizuka-suppressed decay modes J/psi -> gamma omega phi, omega -> pi(+)pi(-)pi(0), phi -> K+K-. A strong deviation (> 30 sigma) from three-body J/psi -> gamma omega phi phase space is observed near the omega phi mass threshold that is consistent with a previous observation reported by the BESII experiment. A partial wave analysis with a tensor covariant amplitude that assumes that the enhancement is due to the presence of a resonance, the X(1810), is performed and confirms that the spin-parity of the X(1810) is 0(++). The mass and width of the X(1810) are determined to be M = 1795 +/- 7(stat)(-5)(+13) (syst) +/- 19(mod) MeV/c(2) and Gamma = 95 +/- 10(stat)(-34)(+21)(syst) +/- 75(mod) MeV/c(2), respectively, and the product branching fraction is measured to be B(J/psi -> gamma X(1810)) x B(X(1810) -> omega phi) = (2.00 +/- 0.08(stat)(-1.00)(+0.45)(syst) +/- 1.30(mod)) x 10(-4). These results are consistent within errors with those of the BESII experiment. DOI: 10.1103/PhysRevD.87.032008