## Dissertations, Theses, and Masters Projects

1989

Dissertation

#### Degree Name

Doctor of Philosophy (Ph.D.)

Physics

Morton Eckhause

#### Abstract

A sensitive search has been carried out for the rare decay $\rm K\sb{L}\to\mu e$. This decay violates conservation of separate lepton-number and thus is forbidden in the Standard Model of electro-weak interactions. Many new models have been proposed which could permit this process. The data were collected in the B5 beamline of the Alternating Gradient Synchrotron facility at the Brookhaven National Laboratory during the Spring, 1988 slow-extracted beam running period. The experiment was sensitive to approximately fifty million $\rm K\sb{L}\to\pi\pi$ decays. No $\rm K\sb{L}\to\mu e$ candidate events were detected. The 90% confidence level upper limit for the branching ratio is $\rm B(K\sb{L}\to\mu e) < 2.2 \times 10\sp{-10}$. This limit places a constraint on the mass of exotic particles proposed in many new theories.

#### DOI

https://dx.doi.org/doi:10.21220/s2-tzke-ej63