Search for the X (2370) and observation of ?c ? ???? in J/? ? ?????

Abstract

Using a sample of 1.31 x 10(9) J/psi events collected with the BESIII detector, we perform a study of J/psi -> gamma eta eta eta' to search for the X(2370) and eta(c) in the eta eta eta' invariant mass distribution. No significant signal for the X(2370) is observed, and we set an upper limit for the product branching fraction of B(J/psi -> gamma X(2370) . B(X(2370) -> eta eta eta') < 9.2 x 10(-6) at the 90% confidence level. A clear eta(c) signal is observed for the first time, yielding a product branching fraction of B(J/psi -> gamma eta(c)).B(eta c -> eta eta eta') = (4.86 +/- 0.62(stat) +/- 0.45(sys)) x 10(-5).