## Dissertations, Theses, and Masters Projects

1992

Dissertation

#### Degree Name

Doctor of Philosophy (Ph.D.)

Physics

Robert E Welsh

#### Abstract

This thesis presents the results of a measurement of the branching fraction of the $K\sb{L}\to\mu\bar{\mu}$ decay. This decay is scGIM supressed in the Standard Model, and provides a useful test of that model. Additionally, the degree of deviation from the unitary limit provides a useful test for several other models. The experiment was performed at the Brookhaven National Laboratory Alternating Gradient Synchrotron facility. The apparatus consisted of a two-magnet mass spectrometer, together with dual electromagnetic and muon particle identification systems. A total of 281 $K\sb{L}\to\mu\bar{\mu}$ events were observed. Normalizing to the 15,768 $K\sb{L}\to\pi\bar{\pi}$ events observed results in a branching fraction of $\Gamma(K\sb{L}\to\mu\bar{\mu})/\Gamma(K\sb{L}\to$ all) = (7.6 $\pm$ 0.5) $\times$ 10$\sp{-9}$.

#### DOI

https://dx.doi.org/doi:10.21220/s2-ztsa-fe04