Dalitz Plot Analysis of η_c → K⁺K⁻η and η_c → K⁺K⁻π⁰ in Two-Photon Interactions

We study the processes γγ→K⁺K⁻η and γγ→K⁺K⁻π⁰ 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(nS) (n = 2, 3, 4) resonances. We observe η_c → K⁺K⁻π⁰ and η_c → K⁺K⁻η decays, measure their relative branching fraction, and perform a Dalitz plot analysis for each decay. We observe the K₀*(1430) → K η decay and measure its branching fraction relative to the K π decay mode to be R(K₀*(1430)) = ℬ(K₀*(1430) → K η) / ℬ(K₀*(1430) → K π) = 0.092 ± 0.025_(-0.025)^(+0.010). The η_c → K⁺K⁻η and K₀*(1430) → Kη results correspond to the first observations of these channels. The data also show evidence for η_c(2S) → K⁺K⁻π⁰ and first evidence for η_c(2S) → K⁺K⁻η.