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Measurement of the Muonic Branching Fractions of the Narrow Upsilon Resonances

G. S. Adam·CLEO Collaboration
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Abstract

The decay branching fractions of the three narrow Upsilon resonances to mu+ mu- have been measured by analyzing about 4.3 1/fb e+e- data collected with the CLEO III detector. The branching fraction B(Y(1S) -> mu+ mu-) = (2.49 +- 0.02 +- 0.07)% is consistent with the current world average but B(Y(2S) -> mu+ mu-) = (2.03 +- 0.03 +- 0.08)% and B(Y(3S) -> mu+ mu-) = (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 Y(2S) and Y(3S) resonances and lower other branching fractions that rely on these decays in their determination.

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G. S. Adam, CLEO Collaboration. 2005-02-01. Measurement of the Muonic Branching Fractions of the Narrow Upsilon Resonances. https://doi.org/10.1103/physrevlett.94.012001

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