Extra Higgs bosons in ttbar production at the LHC

TL;DR

This paper investigates how extra Higgs bosons in extended models affect top-antitop production at the LHC, highlighting interference effects and potential observability with current luminosities.

Contribution

It analyzes the impact of additional Higgs fields in SUSY and Little Higgs models on ttbar production, emphasizing interference effects over narrow-width contributions.

Findings

Interference dominates over narrow-width effects in ttbar production.

Mass differences and loop contributions are crucial for detection.

Current LHC luminosity can probe specific parameter regions.

Abstract

The top quark has a large Yukawa coupling with the Higgs boson. In the usual extensions of the standard model the Higgs sector includes extra scalars, which also tend to couple strongly with the top quark. Unlike the Higgs, these fields have a natural mass above 2m_t, so they could introduce anomalies in ttbar production at the LHC. We study their effect on the ttbar invariant mass distribution at sqrt{s}=7 TeV. We focus on the bosons (H,A) of the minimal SUSY model and on the scalar field (r) associated to the new scale f in Little Higgs (LH) models. We show that in all cases the interference with the standard amplitude dominates over the narrow-width contribution. As a consequence, the mass difference between H and A or the contribution of an extra T-quark loop in LH models become important effects in order to determine if these fields are observable there. We find that a 1 fb^{-1} luminosity could probe the region tan beta \le 3 of SUSY and v/(sqrt{2}f) \ge 0.3 in LH models.