Study of the process e^+e^- →ηηγ in the energy range √(s) = 1.17–2.00 GeV with the SND detector

The process e^+e^-→ηηγ is studied in the center-of-mass energy range 1.17–2.00 GeV using data with an integrated luminosity of 201 pb ^-1 collected by the SND detector at the VEPP-2000 e^+e^- collider. The e^+e^-→ηηγ cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the ϕη intermediate state. Our result on the e^+e^-→ηηγ cross section is consistent with the e^+e^-→ϕη measurement in the ϕ→ K^+ K^- mode. The search for radiative processes contributing to the e^+e^-→ηηγ cross section is performed, and no significant signal is observed.