Searching for extra Higgs bosons via $pp\to H,A\to τμ, ττ$ at the Large Hadron Collider

Abstract

We follow the heavy Higgs searches at the Large Hadron Collider (LHC) for H → τ µ by CMS, and H → τ τ by ATLAS and CMS, to study the prospects of discovering the extra Higgs states in pp → H, A → τ µ, τ τ with eµ + / E T and j τ µ + / E T final states, where j τ = π , ρ , a 1 and / E T is missing transverse energy. In a general two Higgs doublet model framework without Z 2 symmetry, extra Yukawa couplings ρ τ τ and ρ τ µ can drive H, A → τ τ and τ µ channels at hadron colliders, following gluon-gluon fusion production with extra ρ tt couplings. The light Higgs boson h( 125) is found to resemble closely the Standard Model Higgs boson. In the alignment limit of cos γ → 0 for h-H mixing, flavor changing neutral Higgs couplings such as h → τ µ are naturally suppressed, but the couplings of the heavier H is optimized by sin γ → 1. We define various signal regions for H, A → τ µ and τ τ , and evaluate physics backgrounds from dominant processes with realistic acceptance cuts and tagging efficiencies. Two different studies are presented: we first perform a parton level study without any hadronization and with minimal detector smearing; we then include hadronization using PYTHIA 8.2 and fast detector simulation using DELPHES to give event level simulation. Results for √ s = 13 TeV appear promising, which we extend further to √ s = 14 TeV for the High Luminosity LHC.

Flavor-changing neutral currents in the Higgs sector

“…Gori et al 57 showed in the context of a flavorful model that the dominant decay mode of a heavy scalar can be into a top and a charm and they discuss production and detection of this mode at the LHC. They also point out that the dominant decay mode of the charged Higgs, even about the top threshold, can be into charm plus bottom; a study of this process at linear colliders was recently carried out by Hou et al 58 In addition, Hou et al 27,59 studied flavor changing leptonic decays of heavy Higgs bosons at the LHC and future proton-proton colliders. In fact, CMS has been searching 60 for lepton flavor violating decays of heavy Higgs bosons in Run II.…”

Two-Higgs-doublet model and quark-lepton unification

“…The region shaded in red corresponds to the exclusion limit from searches by the ATLAS [28] collaboration for a heavy scalar decaying into a two tau leptons with integrated luminosity of 139 fb −1 (see also ref. [30]). We fix the trilinear coupling to λ eff = 0.1 which affects only the process involving H.…”