A search for exotic decays of the Higgs boson to a pair of light pseudoscalar particles a$_1$ is performed under the hypothesis that one of the pseudoscalars decays to a pair of opposite sign muons and the other decays to b$\overline{\mathrm{b}}$. Such signatures are predicted in a number of extensions of the standard model (SM), including next-to-minimal supersymmetry and two-Higgs-doublet models with an additional scalar singlet. The results are based on a data set of proton-proton collisions corresponding to an integrated luminosity of 35.9 fb$^{-1}$, accumulated with the CMS experiment at the CERN LHC in 2016 at a centre-of-mass energy of 13 TeV. No statistically significant excess is observed with respect to the SM backgrounds in the search region for pseudoscalar masses from 20 GeV to half of the Higgs boson mass. Upper limits at 95% confidence level are set on the product of the production cross section and branching fraction, $\sigma_{\mathrm{h}}\mathcal{B}$(h $\to$ a$_1$ a$_1$ $\to$ $\mu^+\mu^-\mathrm{b}\bar{\mathrm{b}}$), ranging from 5 to 33 fb, depending on the pseudoscalar mass. Corresponding limits on the branching fraction, assuming the SM prediction for $\sigma_{\mathrm{h}}$, are (1$-$7)$\times$ 10$^{-4}$.
Observed and expected upper limits at 95% CL on the product of the Higgs boson production cross section and B(h->aa->mumubb)
Observed and expected upper limits at 95% CL on the branching fraction of (h->aa->mumubb)
The $\chi_\mathrm{b1}$(3P) and $\chi_\mathrm{b2}$(3P) states are observed through their $\Upsilon$(3S) $\gamma$ decays, using an event sample of proton-proton collisions collected by the CMS experiment at the CERN LHC. The data were collected at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of 80.0 fb$^{-1}$. The $\Upsilon$(3S) mesons are identified through their dimuon decay channel, while the low-energy photons are detected after converting to e$^+$e$^-$ pairs in the silicon tracker, leading to a $\chi_\mathrm{b}$(3P) mass resolution of 2.2 MeV. This is the first time that the $J =$ 1 and 2 states are well resolved and their masses individually measured: 10$\,$513.42 $\pm$ 0.41 (stat) $\pm$ 0.18 (syst) MeV and 10$\,$524.02 $\pm$ 0.57 (stat) $\pm$ 0.18 (syst) MeV; they are determined with respect to the world-average value of the $\Upsilon$(3S) mass, which has an uncertainty of 0.5 MeV. The mass splitting is measured to be 10.60 $\pm$ 0.64 (stat) $\pm$ 0.17 (syst) MeV.
Observation of the $\chi_{b1}(3P)$ and $\chi_{b2}(3P)$ and measurement of their masses.
Observation of the $\chi_{b1}(3P)$ and $\chi_{b2}(3P)$ and mass splitting measurement.
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