Search for charged Higgs bosons decaying into top and bottom quarks in lepton+jets final states in proton-proton collisions at √s=13 TeV

A bstract A search is presented for charged Higgs bosons (H ± ) in proton-proton (pp) collision events via the pp → (b)H ± processes, with H ± decaying into top (t) and bottom (b) quarks. The search targets final states with one lepton, missing transverse momentum, and two or more b jets. The analysis is based on data collected at a center-of-mass energy of 13 TeV with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 138 fb − 1 . We search for charged Higgs bosons in the 200 GeV to 1 TeV mass range. The results are interpreted within the generalized two-Higgs-doublet model (g2HDM). This model predicts additional Yukawa couplings of the Higgs bosons to the top quark ρ tt , the top and charm quark ρ tc , and the top and up quark ρ tu . This search focuses on the real components of ρ tt and ρ tc , which are probed up to values of unity. An excess is observed with respect to the standard model expectation with a local significance of 2.4 standard deviations for a signal with an H ± boson mass ( m_H± m H ± ) of 600 GeV. Limits are derived on the product of the cross section σ (pp → (b)H ± ) and branching fraction ℬ(H ± → tb , t → b ℓν ), where ℓ = e , μ . The values of ρ tc ≳ 0.11–0.38 are excluded at 95% confidence level, depending on the m_H± m H ± and ρ tt assumptions. The results represent the first search for charged Higgs bosons within the g2HDM framework in the single-lepton final states and complement the existing results on additional neutral Higgs bosons perfomed in the same-sign top quark pair, three top quark, or four top quark final states, constraining extra Yukawa couplings for the neutral Higgs bosons below the TeV scale.