Published in:

Physical Review D 81,3 (2010)


We report evidence for the ground state of bottomonium, eta(b)(1S), in the radiative decay Gamma(3S) -> gamma eta(b) in e(+)e(-) annihilation data taken with the CLEO III detector. Using 6 X 10(6) Gamma(dS) decays, and assuming Gamma(eta(b)) = 10 +/- 5 MeV/c(2), we obtain B(Gamma(3S) -> gamma eta(b)) = (7.1 +/- 1.8 +/- 1.3) X 10(-4), where the first error is statistical and the second is systematic. The statistical significance is -4 sigma. The mass is determined to be M(eta(b)) = 9391.8 +/- 6.6 +/- 2.0 MeV/c(2), which corresponds to the hyperfine splitting Delta M-hf(1S)(b) = 68.5 +/- 6.6 +/- 2.0 MeV/c(2). Using 9 X 10(6) Gamma(2S) decays, we place an upper limit on the corresponding Gamma(2S) decay, B(Gamma(2S) -> gamma eta(b)) < 8.4 X 10(-4) at 90% confidence level.

Date of this Version

February 2010



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