A New Measurement of eta_b(1S) From Upsilon(3S) Radiative Decay at CLEO

TL;DR

This paper reports a new measurement of the eta_b(1S) bottomonium ground state mass and hyperfine splitting using CLEO data, confirming previous results and providing precise values for these parameters.

Contribution

The study presents a new measurement of eta_b(1S) mass and hyperfine splitting from Upsilon(3S) radiative decay, confirming earlier findings with improved precision.

Findings

Eta_b(1S) mass measured as 9391.8 MeV

Hyperfine splitting determined as 68.5 MeV

Branching fraction for decay is (7.1 ± 1.8) x 10^-4

Abstract

Using CLEO data, we report on the confirmation of the eta_b(1S0) ground state of bottomonium in the radiative decay Upsilon(3S) -> gamma eta_b. We determine its mass to be M(eta_b) = 9391.8 +- 6.6 +- 2.1 MeV, which corresponds to the hyperfine splitting Delta M_hf(1S) = 68.5 +- 6.6 +- 2.0 MeV, and the branching fraction B(Upsilon(3S) -> gamma eta_b) = (7.1 +- 1.8 +- 1.1) x 10^-4. These results agree with those previously reported by BaBar.