The process e+e− → ηπ0γ is studied in the range of center-of-mass (c.m.) collision energies between 1.05 and 2.00 GeV on the basis of data corresponding to an integrated luminosity of 94.5 pb-1 that were accumulated in an experiment with the SND detector at the VEPP-2000 e+e− collider. The cross section for this process was measured for the first time and was found to receive a dominant contribution from the mechanism of a transition through an ωη intermediate state. The cross section measured for the process e+e− → ωη → ηπ0γ agrees with the results of earlier measurements in the channel e+e− → π+π−π0η. At a level of 5.7 standard deviations (5.7 σ), it is established that the process e+e− → ηπ0γ is not fully described by hadronic intermediate states of the VP type. The cross section was measured for this missing contribution, which may be generated by radiative processes—for example, e+e− → a0(1450)γ. It ranges from 15 to 20 pb over a broad energy interval extending from 1.3 to 1.9 GeV.
Предметные области OECD FOS+WOS
- 1.03 ФИЗИЧЕСКИЕ НАУКИ И АСТРОНОМИЯ
- 1.03.UN ФИЗИКИ, ЯДЕРНАЯ
- 1.03.UP ФИЗИКА, ЧАСТИЦЫ И ПОЛЯ