Observation of theηb(2S)Meson inΥ(2S)→γηb(2S),ηb(2S)→Hadrons and Confirmation of theηb(1S)Meson

Abstract

The data for 9.3 million Υ(2S) and 20.9 million Υ(1S) taken with the CLEO III detector have been used to study the radiative population of states identified by their decay into 26 different exclusive hadronic final states. In the Υ(2S) decays, an enhancement is observed at a ~5σ level at a mass of 9974.6±2.3(stat)±2.1(syst) MeV. It is attributed to η(b)(2S) and corresponds to the Υ(2S) hyperfine splitting of 48.7±2.3(stat)±2.1(syst) MeV. In the Υ(1S) decays, the identification of η(b)(1S) is confirmed at a ~3σ level with M[η(b)(1S)] in agreement with its known value.