Search for a narrow resonance decaying to a pair of muons in proton-proton collisions at 13 TeV

A search is presented for a narrow resonance decaying to a pair of muons using 13 TeV proton-proton collision data recorded by the CMS experiment at the CERN LHC. The search in the $45-75$ and $110-200$ GeV resonance mass ranges uses fully reconstructed event data, corresponding to an integrated luminosity of 137 fb$^{-1}$. The search in the $11.5-45.0$ GeV mass range uses 96.6 fb$^{-1}$ of data collected using a dedicated set of high rate dimuon triggers with low thresholds, which store a reduced amount of trigger level information. No significant resonant peaks are observed. The search sets the strongest constraints on a hypothetical dark photon heavier than 11.5 GeV.