Search for Lepton Flavor Violating Decays of the Neutral Kaon

TL;DR

The Fermilab KTeV experiment searched for lepton flavor violating decays of the KL meson across three modes, found no evidence, and set new upper limits on their branching ratios, constraining new physics models.

Contribution

First experimental search for specific lepton flavor violating decays of the KL meson with improved upper limits on branching ratios.

Findings

No events observed in the signal region for any decay mode.

Set upper limits on branching ratios at 90% confidence level.

Results constrain theories predicting lepton flavor violation in kaon decays.

Abstract

The Fermilab KTeV experiment has searched for lepton flavor violating decays of the KL meson in three decay modes. We observe no events in the signal region for any of the modes studied, and we set the following upper limits for their branching ratios at the 90% CL: BR(KL--> pi0 mu e) < 7.56 x 10^(-11); BR(KL--> pi0 pi0 mu e) < 1.64 x 10^(-10); BR(pi0 --> mu e) < 3.59 x 10^{-10).