Observation of chi(c2) -> eta 'eta ' and chi(c0,2) -> eta eta '

Abstract

Using a sample of 448.1 x 10(6) Psi(3686) events collected with the BESIII detector in 2009 and 2012, we study the decays chi(c0,2) -> eta 'eta ' and eta eta '. The decays chi(c2) -> eta 'eta ', chi(c0) -> eta eta ' and chi(c2) -> eta eta ' are observed for the first time with statistical significances of 9.6 sigma, 13.4 sigma and 7.5 sigma, respectively. The branching fractions are determined to be B(chi(c0) -> eta 'eta ') = (2.19 +/- 0.03 +/- 0.14) x 10(-3), B(chi(c2) -> eta 'eta ') = (4.76 +/- 0.56 +/- 0.38) x 10(-5), B(chi(c0) -> eta eta ') = (8.92 +/- 0.84 +/- 0.65) x 10(-5) and B(chi(c2) -> eta eta ') = (2.27 +/- 0.43 +/- 0.25) x 10(-5), where the first uncertainties are statistical and the second are systematic. The precision for the measurement of B(chi(c0) -> eta 'eta ') thorn is significantly improved compared to previous measurements. Based on the measured branching fractions, the role played by the doubly and singly Okubo-Zweig-Iizuka disconnected transition amplitudes for chi(c0,2) decays into pseudoscalar meson pairs can be clarified.