Search for the Rare Decay D0→μ+μ− in Proton-Proton Collisions at s=13.6 TeV

A search for the rare decay D0 → μþμ− is reported using proton-proton collision events at ffiffi s p ¼ 13.6 TeV collected by the CMS detector in 2022–2023, corresponding to an integrated luminosity of 64.5 fb−1. 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 D0 mesons obtained from Dþ → D0πþ decays. No significant excess is observed. A limit on the branching fraction of BðD0 → μþμ−Þ < 2.4 × 10−9 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.