Observation of the Exclusive Reaction e+e- -> phi eta at sqrt{s}=10.58 GeV

Abstract

We report the observation of $\e^+e^-\to ϕη$ near $\sqrt{s}$ = 10.58 GeV with 6.5 $σ$ significance in the $K^+K^-γγ$ final state in a data sample of 224 $fb^{-1}$ collected by the BaBar experiment at the PEP-II $e^+e^-$ storage rings. We measure the restricted radiation-corrected cross section to be $σ(\e^+e^- \to ϕη) =$$2.1\pm 0.4 (\mathrm{stat})\pm 0.1(\mathrm{syst}) \mathrm{fb}$ within the range $|\cosθ^*| < 0.8$, where $θ^*$ is the center-of-mass polar angle of the $ϕ$ meson. The $ϕ$ meson is required to be in the invariant mass range of 1.008 $< m_ϕ <$ 1.035 \gevcc. The radiation-corrected cross section in the full $\cosθ^*$ range is extrapolated to be $2.9\pm 0.5 (\mathrm{stat})\pm 0.1(\mathrm{syst}) \mathrm{fb}$.