Measurement of the ηb(1S) mass and the branching fraction for Υ(3S)→γηb(1S)

Journal article

We report evidence for the ground state of bottomonium, ηb(1S), in the radiative decay Υ(3S)→γηb in e+e- annihilation data taken with the CLEO III detector. Using 6×106 Υ(3S) decays, and assuming Γ(ηb)=10±5MeV/c2, we obtain B(Υ(3S)→γηb)=(7.1±1.8±1.3)×10 -4, where the first error is statistical and the second is systematic. The statistical significance is ∼4σ. The mass is determined to be M(ηb)=9391.8±6.6±2.0MeV/c2, which corresponds to the hyperfine splitting ΔMhf(1S)b=68.5±6.6±2.0MeV/c2. Using 9×106 Υ(2S) decays, we place an upper limit on the corresponding Υ(2S) decay, B(Υ(2S)→γηb)<8. 4×10-4 at 90% confidence level. © 2010 The American Physical Society.

Authors: Bonvicini, G; Cinabro, D; Lincoln, A; Smith, M; Zhou, P

• Journal: Physical Review D
• Volume: 81
• Issue: 3
• Publication date: 2010-02-24
• DOI: 10.1103/PhysRevD.81.031104
• EISSN: 1550-2368
• ISSN: 1550-7998
• Language: English