Search for the Rare Decay (Formula Presented) in Proton-Proton Collisions at (Formula Presented)

Abstract

A search for the rare decay (Formula presented) is reported using proton-proton collision events at (Formula presented) collected by the CMS detector in 2022-2023, corresponding to an integrated luminosity of (Formula presented). This is the first analysis to use a newly developed inclusive dimuon trigger, expanding the scope of the CMS flavor physics program. The search uses (Formula presented) mesons obtained from (Formula presented) decays. No significant excess is observed. A limit on the branching fraction of (Formula presented) at 95% confidence level is set. This is the most stringent upper limit set on any flavor changing neutral current decay in the charm sector. © 2025 CERN, for the CMS Collaboration.