Search for Rare and Forbidden Charm Meson Decays at Fermilab E791

TL;DR

This study conducted a blind search for rare and forbidden charm meson decays involving muons and electrons using Fermilab E791 data, setting new upper limits on their branching fractions.

Contribution

First comprehensive search for multiple rare charm meson decays at Fermilab, providing new upper limits and improving existing constraints on these processes.

Findings

No evidence of the targeted rare decays was observed.

Established upper limits for 24 decay modes at 90% confidence level.

Eight decay modes reported for the first time with no previous limits.

Abstract

We report the results of a blind search for flavor-changing neutral current, lepton-flavor violating, and lepton-number violating decays of D+, D(s)+, and D0 mesons (and their antiparticles) into modes containing muons and electrons. Using data from Fermilab charm hadroproduction experiment E791, we examine the pi l l and K l l decay modes of D+ and D(s)+ and the l+ l- decay modes of D0. No evidence for any of these decays is found. Therefore, we present branching-fraction upper limits at 90% confidence level for the 24 decay modes examined. Eight of these modes have no previously reported limits, and fourteen are reported with significant improvements over previously published results.