Search for a Light NMSSM Higgs Boson in the b-Quark Final State at the LHC

A search for a light neutral Higgs boson decaying into a pair of b quarks is presented.Such Higgs bosons are predicted by certain scenarios of the Next-to-Minimal Supersymmetric Standard Model (NMSSM), whose Higgs sector has two complex Higgsdoublets and an additional Higgs singlet. If the lightest Higgs boson has a sizeablesinglet admixture, it may have escaped detection in previous searches at LEP, Tevatron, and LHC, but could be produced at a substantial rate in neutralino decayswithin supersymmetric cascades. This analysis is the first search for Higgs bosonsin the mass range below 100 GeV in the b-quark final state at the LHC. It uses adata sample corresponding to an integrated luminosity of 19.7 fb−1 , which has beenrecorded by the CMS experiment in 2012 at a centre-of-mass energy of 8 TeV. Eventswith a pair of b-tagged jets, at least two very energetic jets, and large missing energyare selected. The invariant mass of the two selected b-tagged jets is used to extractthe signal. The observed invariant-mass spectrum is in good agreement with thebackground expected from Standard-Model processes. The results are interpreted interms of cross-section limits and within light-Higgs-boson scenarios of the NMSSM.The modified P4 benchmark scenario of the NMSSM is excluded by this analysis.