The decay branching fractions of the three narrow υ resonances to μ+ μ- have been measured by analyzing about 4.3 fb-1 e+ e- data collected with the CLEO III detector. The branching fraction 25(υ(1S) → μ+ μ-) = (2.49 ± 0.02 ± 0.07)% is consistent with the current world average, but ℬ(υ(2S) → μ+ μ-) = (2.03 ± 0.03 ± 0.08)% and ℬ(υ(3S) → μ+ μ-) = (2.39 ± 0.07 ± 0.10)% are significantly larger than prior results. These new muonic branching fractions imply a narrower total decay width for the υ(2S) and υ(3S) resonances and lower other branching fractions that rely on these decays in their determination.
ASJC Scopus subject areas
- Physics and Astronomy(all)