Search for Higgs and Z boson decays to J/Ψ or Y pairs in the four-muon final state in proton-proton collisions at √s = 13 TeV

Abstract

A search for decays of the Higgs and Z boson to pairs of \(J/\psi \) or \(Y\left(\mathrm{nS}\right)\) (n = 1, 2, 3) mesons, with their subsequent decay to \({\mu }^{+}{\mu }^{-}\) pairs, is presented. The analysis uses data from proton-proton collisions at \(\sqrt{s}=13\phantom{\rule{0.2em}{0ex}}\text{TeV}\), collected with the CMS detector at the LHC in 2017 and corresponding to an integrated luminosity of 37.5\(\phantom{\rule{0.2em}{0ex}}{\text{fb}}^{-1}\). While an observation of such a decay with this sample would indicate the presence of physics beyond the standard model, no significant excess is observed. Upper limits at 95% confidence level are placed on the branching fractions of these decays. In the \(J/\psi \) pair channel, the limits are \(1.8×{10}^{-3}\) and \(2.2×{10}^{-6}\) for the Higgs and Z boson, respectively, while in the combined \(Y\left(\mathrm{nS}\right)\) pair channel, the limits are \(1.4×{10}^{-3}\) and \(1.5×{10}^{-6}\), respectively, when the mesons from the Higgs and Z boson decay are assumed to be unpolarized. When fully longitudinal and transverse polarizations are considered the limits reduce by about 22–29% and increase by about 10–13%, respectively.