Search for Higgs and Z boson decays to J/psi or Y pairs in the four-muon final state in proton-proton collisions at root s=13 TeV<bold> </bold>
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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.