ISSN:
1434-6052
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract Using the Crystal Ball detector at thee + e − storage ring DORIS II, we have measured the branching fraction to muon pairsB μμ of the Υ(1S) and Υ(2S) resonances and for the first time the product of the muonic partial widthΓ μμ and the branching fraction to electronsB ee for both resonances. We obtain $$\begin{gathered} B_{\mu \mu } (1S) = (2.31 \pm 0.12 \pm 0.10)\% , \hfill \\ \Gamma _{\mu \mu } (1S) \cdot B_{ee} (1S) = (31.2 \pm 1.6 \pm 1.7)eV, \hfill \\ \end{gathered} $$ and $$\begin{gathered} B_{\mu \mu } (2S) = (1.22 \pm 0.28 \pm 0.19)\% , \hfill \\ \Gamma _{\mu \mu } (2S) \cdot B_{ee} (2S) = (6.5 \pm 1.5 \pm 1.0)eV. \hfill \\ \end{gathered} $$ Inserting the present world average value ofB ee (1S)=(2.52±0.17)%, we determine the muonic partial width of the Υ(1S) as $$\Gamma _{\mu \mu } (1S) = (1.24 \pm 0.06 \pm 0.11)keV.$$ In addition, we present the first indication of the expected interference between μ-pair production in the continuum and in Υ(1S) decays.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01597555
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