Search for direct production of GeV-scale resonances decaying to a pair of muons in proton-proton collisions at s = 13 TeV

Abstract

A search for direct production of low-mass dimuon resonances is performed using s = 13 TeV proton-proton collision data collected by the CMS experiment during the 2017�2018 operation of the CERN LHC with an integrated luminosity of 96.6 fb?1. The search exploits a dedicated high-rate trigger stream that records events with two muons with transverse momenta as low as 3 GeV but does not include the full event information. The search is performed by looking for narrow peaks in the dimuon mass spectrum in the ranges of 1.1�2.6 GeV and 4.2�7.9 GeV. No significant excess of events above the expectation from the standard model background is observed. Model-independent limits on production rates of dimuon resonances within the experimental fiducial acceptance are set. Competitive or world�s best limits are set at 90% confidence level for a minimal dark photon model and for a scenario with two Higgs doublets and an extra complex scalar singlet (2HDM+S). Values of the squared kinetic mixing coefficient ?2 in the dark photon model above 10?6 are excluded over most of the mass range of the search. In the 2HDM+S, values of the mixing angle sin(?H) above 0.08 are excluded over most of the mass range of the search with a fixed ratio of the Higgs doublets vacuum expectation tan ? = 0.5. � The Author(s) 2024.