A search is presented for a standard model-like Higgs boson decaying to the $\mu^+\mu^-$ or $\mathrm{e^+e^-}$ final states based on proton-proton collisions recorded by the CMS experiment at the CERN LHC. The data correspond to integrated luminosities of 5.0~\mathrm{fb}^{-1} at a centre-of-mass energy of 7~\mathrm{TeV} and 19.7~\mathrm{fb}^{-1} at 8~\mathrm{TeV} for the $\mu^+\mu^-$ search, and of 19.7~\mathrm{fb}^{-1} at a centre-of-mass energy of 8~\mathrm{TeV} for the $\mathrm{e^+e^-}$ search. To enhance the sensitivity of the search, events are categorized by topologies according to production process and dilepton invariant mass resolution. Upper limits on the production cross section times branching fraction at the 95% confidence level are reported for Higgs boson masses in the range from 120 to 150~\mathrm{GeV}. For a Higgs boson with a mass of 125~\mathrm{GeV} decaying to $\mu^+\mu^-$, the observed (expected) upper limit on the production rate is found to be 7.4 ($6.5^{+2.8}_{-1.9}$) times the standard model value. This corresponds to an upper limit on the branching fraction of 0.0016. Similarly, for $\mathrm{e^+e^-}$, an upper limit of 0.0019 is placed on the branching fraction, which is ${\approx}3.7\times10^5$ times the standard model value. These results, together with recent evidence of the 125~\mathrm{GeV} boson coupling to $\tau$-leptons with a larger branching fraction consistent with the standard model, show for the first time that the leptonic couplings of the new boson are not flavour-universal.

Log in to your administrator account to edit.