A search for a light pseudoscalar Higgs boson (a) decaying from the 125 GeV (or a heavier) scalar Higgs boson (H) is performed using the 2016 LHC proton-proton collision data at sqrt(s) = 13 TeV, corresponding to an integrated luminosity of 35.9 fb^−1, collected by the CMS experiment. The analysis considers gluon fusion and vector boson fusion production of the H, followed by the decay H -> aa -> μμττ, and considers pseudoscalar masses in the range 3.6 < m_a < 21 GeV. Because of the large mass difference between the H and the a bosons and the small masses of the a boson decay products, both the μμ and the ττ pairs have high Lorentz boost and are collimated. The ττ reconstruction efficiency is increased by modifying the standard technique for hadronic τ lepton decay reconstruction to account for a nearby muon. No significant signal is observed. Model-independent limits are set at 95% confidence level, as a function of m_a, on the branching fraction (B) for H -> aa -> μμττ, down to 1.5 (2.0) × 10^−4 for mH = 125 (300) GeV. Model-dependent limits on B(H ->aa) are set within the context of two Higgs doublets plus singlet models, with the most stringent results obtained for Type-III models. These results extend current LHC searches for heavier a bosons that decay to resolved lepton pairs and provide the first such bounds for an H boson with a mass above 125 GeV.
Search for a light pseudoscalar Higgs boson in the boosted μμττ final state in proton-proton collisions at sqrt(s) = 13 TeV
Meridiani P.;Amapane N.;Argiro S.;Bellan R.;Bellora A.;Cappati A.;Costa M.;Covarelli R.;Kiani B.;Migliore E.;Monaco V.;Monteil E.;Obertino M. M.;Pacher L.;Pinna Angioni G. L.;Salvatico R.;Siviero F.;Sola V.;Solano A.;Soldi D.;Shchelina K.;Rumerio P.;Ravera F.;
2020-01-01
Abstract
A search for a light pseudoscalar Higgs boson (a) decaying from the 125 GeV (or a heavier) scalar Higgs boson (H) is performed using the 2016 LHC proton-proton collision data at sqrt(s) = 13 TeV, corresponding to an integrated luminosity of 35.9 fb^−1, collected by the CMS experiment. The analysis considers gluon fusion and vector boson fusion production of the H, followed by the decay H -> aa -> μμττ, and considers pseudoscalar masses in the range 3.6 < m_a < 21 GeV. Because of the large mass difference between the H and the a bosons and the small masses of the a boson decay products, both the μμ and the ττ pairs have high Lorentz boost and are collimated. The ττ reconstruction efficiency is increased by modifying the standard technique for hadronic τ lepton decay reconstruction to account for a nearby muon. No significant signal is observed. Model-independent limits are set at 95% confidence level, as a function of m_a, on the branching fraction (B) for H -> aa -> μμττ, down to 1.5 (2.0) × 10^−4 for mH = 125 (300) GeV. Model-dependent limits on B(H ->aa) are set within the context of two Higgs doublets plus singlet models, with the most stringent results obtained for Type-III models. These results extend current LHC searches for heavier a bosons that decay to resolved lepton pairs and provide the first such bounds for an H boson with a mass above 125 GeV.File | Dimensione | Formato | |
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