Dalitz plot analysis of ηc → K+K−η and ηc → K+K−π0 in two-photon interactions

Abstract

We study the processes γ γ → K + K − η and γ γ → K + K − π 0 using a data sample of 519 fb − 1 recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e + e − collider at center-of-mass energies at and near the Υ ( n S ) ( n = 2 , 3 , 4 ) resonances. We observe η c → K + K − π 0 and η c → K + K − η decays, measure their relative branching fraction, and perform a Dalitz plot analysis for each decay. We observe the K ∗ 0 ( 1430 ) → K η decay and measure its branching fraction relative to the K π decay mode to be R ( K ∗ 0 ( 1430 ) ) = B ( K ∗ 0 ( 1430 ) → K η ) B ( K ∗ 0 ( 1430 ) → K π ) = 0.092 ± 0.02 5 + 0.010 − 0.025 . The η c → K + K − η and K ∗ 0 ( 1430 ) → K η results correspond to the first observations of these channels. The data also show evidence for η c ( 2 S ) → K + K − π 0 and first evidence for η c ( 2 S ) → K + K − η .