Search for the rare decay D$^0$ $\to$ $\mu^+\mu^-$ in proton-proton collisions at $\sqrt{s}$ = 13.6 TeV

TL;DR

This paper reports a search for the rare decay D0 to mu+ mu- in proton-proton collisions at 13.6 TeV using CMS data, setting the most stringent upper limit to date on this flavor-changing neutral current process.

Contribution

First analysis utilizing a new inclusive dimuon trigger in CMS, providing the tightest upper limit on D0 to mu+ mu- decay branching fraction.

Findings

No significant excess observed.

Upper limit on branching fraction set at 2.4 x 10^-9.

Most stringent limit on charm sector FCNC decay.

Abstract

A search for the rare decay D$^0$ $\to$ $\mu^+\mu^-$ is reported using proton-proton collision events at $\sqrt{s}$ = 13.6 TeV collected by the CMS detector in 2022$-$2023, corresponding to an integrated luminosity of 64.5 fb$^{-1}$. This is the first analysis to use a newly developed inclusive dimuon trigger, expanding the scope of the CMS flavor physics program. The search uses D$^0$ mesons obtained from D$^{*+}$ $\to$ D$^0\pi^+$ decays. No significant excess is observed. A limit on the branching fraction of $\mathcal{B}$(D$^0$ $\to$ $\mu^+\mu^-$) $\lt$ 2.4 $\times$ 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.