Search for the Flavor-Changing Neutral Current Decay D^0\to\mu^+\mu^- in p\bar{p} Collisions at \sqrt{s}=1.96 TeV

TL;DR

This paper reports a search for the rare decay D^0 to mu+ mu- in proton-antiproton collisions at 1.96 TeV, setting upper limits on its branching fraction due to no observed signal.

Contribution

It provides the first experimental upper limits on the branching fraction of D^0 to mu+ mu- in proton-antiproton collisions at Tevatron energies.

Findings

No signal events observed in the D^0 to mu+ mu- decay channel.

Upper limit on the branching fraction set at 2.5 x 10^-6 (90% CL).

Method used displaced-track trigger and normalization channels for unbiased selection.

Abstract

We report on a search for the flavor-changing neutral current decay D^0\to\mu^+\mu^- in p\bar{p} collisions at \sqrt{s}=1.96 TeV using 65\ipb of data collected by the CDF II experiment at the Fermilab Tevatron Collider. A displaced-track trigger selects long-lived D^0 candidates in the D^0\to\mu^+\mu^- search channel, the kinematically similar D^0\to\pi^+\pi^- channel used for normalization, the Cabbibo-favored D^0\to K^+\pi^- channel used to optimize the selection criteria in an unbiased manner, and their charge conjugates. Finding no signal events in the D^0\to\mu^+\mu^- search window, we set an upper limit on the branching fraction {\cal B}(D^0\to\mu^+\mu^-)\leq 2.5E-6 (3.3E-6) at the 90% (95%) confidence level.