Abstract
A search for exotic decays of the Higgs boson to a pair of light pseudoscalar particles a1 is performed under the hypothesis that one of the pseudoscalars decays to a pair of opposite sign muons and the other decays to bb‾. 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, σhB(h→a1a1→μ+μ−bb‾), ranging from 5 to 33 fb, depending on the pseudoscalar mass. Corresponding limits on the branching fraction, assuming the SM prediction for σh, are (1–7)×10−4.
Highlights
The discovery of the particle identified as the Higgs boson by the ATLAS and CMS experiments [1,2,3] at the CERN LHC [4] has opened a new era in the history of particle physics
For ma1 = 40 GeV, the b tagging uncertainties arising from light flavor (LF) contamination and jet energy scale (JES) amount to 17 and 14%, respectively
A search for the Higgs boson decay to a pair of new pseudoscalars h → a1a1 → μ+μ−bb, motivated by the next-to-minimal supersymmetric standard model and other extensions to twoHiggs-doublet models, is carried out using a sample of protonproton collision data corresponding to an integrated luminosity of 35.9 fb−1 at 13 TeV centre-of-mass energy
Summary
The discovery of the particle identified as the Higgs boson by the ATLAS and CMS experiments [1,2,3] at the CERN LHC [4] has opened a new era in the history of particle physics. Though the signal selection is optimised for the h → a1a1 → μ+μ−bb process, decays of h → a1a1 → μ+μ−τ +τ − can contribute to the selected sample if hadronically decaying τ leptons are misidentified as b quark jets Such a contribution is found to be negligible using the benchmark scenario, in some parts of the parameter space the enhancement in B(a1 → τ +τ −) can lead to a nonnegligible fraction of these events surviving the selection. This is taken into account in the scan over the (ma , tan β) plane in the type III 2HDM+S, as for certain values, the increase in μ+μ−τ +τ − signal can affect the sensitivity.
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