Updated Search for the Flavor-Changing Neutral-Current Decay D^0 \to {\mu} + {\mu}-

TL;DR

This paper reports a search for the rare flavor-changing neutral-current decay D0 to mu+ mu- in proton-antiproton collisions, setting upper limits on its branching fraction and improving constraints on new physics models.

Contribution

First search for D0 to mu+ mu- decay at Fermilab Tevatron, establishing new upper limits on its branching fraction.

Findings

Upper limit on branching fraction < 2.1 x 10^-7 at 90% CL

Used displaced vertex trigger for long-lived D0 candidates

Normalized using D0 to K- pi+ decay mode

Abstract

We report on a search for the flavor-changing neutral-current decay D0 \to {\mu}+ {\mu}- in pp collisions at \surd s = 1.96 TeV using 360 pb-1 of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. A displaced vertex trigger selects long-lived D0 candidates in the {\mu}+ {\mu}-, {\pi}+{\pi}-, and K-{\pi}+ decay modes. We use the Cabibbo-favored D0 \to K-{\pi}+ channel to optimize the selection criteria in an unbiased manner, and the kinematically similar D0 \to{\pi}+ {\pi}- channel for normalization. We set an upper limit on the branching fraction (D0 --> {\mu}+ {\mu}-) < 2.1 E-7 (3.0 E-7) at the 90% (95%) confidence level.