Measurement of the absolute branching fractions of J/ψ → γη and η decay modes

Based on a data sample of (1.0087 +/- 0.0044) x 10(10) J/psi events collected by the BESIII detector at the BEPCII accelerator, the absolute branching fraction (BF) of the decay J/psi -> gamma eta is measured with high precision using events in which the radiative photon converts to e(+)e(-). Using the measured absolute BF of J/psi -> gamma eta, the absolute BFs of four dominant. decay modes are measured for the first time. The results are B(J/psi -> gamma eta) = (1.067 +/- 0.005 +/- 0.023) x 10(-3), B(eta ->gamma gamma) = (39.86 +/- 0.04 +/- 0.99)%, B(eta ->pi(0)pi(0)pi(0)) = (31.96 +/- 0.07 +/- 0.84)%, B(eta -> pi(+)pi(-)pi(0)) = (23.04 +/- 0.03 +/- 0.54)%, and B(eta -> pi(+)pi(-)gamma) = (4.38 +/- 0.02 +/- 0.10)%, where the first and second uncertainties are statistical and systematic, respectively. The results are consistent with the world average values within two standard deviations.

Automated summary

Using a data sample collected by the BESIII detector, the absolute branching fraction of the decay J/psi -> gamma eta is measured with high precision, as well as the absolute branching fractions of four dominant decay modes for the first time. The results are consistent with the world average values within two standard deviations.