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Compact Muon Solenoid
LHC, CERN

CMS-PAS-HIG-22-007
Search for exotic Higgs boson decays to a pair of pseudoscalars in the $ \mu\mu\mathrm{bb} $ and $ \tau\tau\mathrm{bb} $ final states in proton-proton collisions with the CMS experiment
Abstract: A search for the exotic decays of a standard model like Higgs boson (H) with a 125 GeV mass to a pair of light pseudoscalars $ \mathrm{a}_1 $ is performed in final states where one pseudoscalar decays to two b quarks and the other to two $ \tau $ leptons or muons. A data sample of proton-proton collisions at $ \sqrt{s}= $ 13 TeV corresponding to an integrated luminosity of 138 fb$ ^{-1} $ recorded with the CMS detector is exploited. No statistically significant excess is observed over the standard model backgrounds. Upper limits are set, at 95% confidence level (CL), on the Higgs boson branching fraction to $ \ell\ell\mathrm{b}\mathrm{b} $ via a pair of $ \mathrm{a}_1 $, where $ \ell $ stands for muons and tau leptons. The limits depend on the pseudoscalar mass $ m_{\mathrm{a}_1} $. The observed limits are in the range (0.17-3.3) $\times$ 10$^{-4} $ and (1.7-7.6) $\times$ 10$^{-2} $ in the $ \mu\mu\mathrm{b}\mathrm{b} $ and $ \tau\tau\mathrm{b}\mathrm{b} $ final states, respectively. The two final states are combined to obtain exclusion limits of the branching fraction $ \mathrm{B}(\mathrm{H}\to\mathrm{a}_1\mathrm{a}_1\to\ell\ell\mathrm{b}\mathrm{b}) $ at 95% CL for a broad class of models of a two Higgs doublet extended with a scalar singlet (2HDM+S). Upper bounds on the Higgs boson branching fraction $ \mathrm{B}(\mathrm{H}\to\mathrm{a}_1\mathrm{a}_1) $ are also extracted from the combination. $ \mathrm{B}(\mathrm{H}\to\mathrm{a}_1\mathrm{a}_1) $ values above 0.23 are excluded at 95% CL for most Type-II 2HDM+S models for $ m_{\mathrm{a}_1} $ values between 15 and 60 GeV.
CMS Publications
Compact Muon Solenoid
LHC, CERN