Effects of Top-quark Compositeness on Higgs Boson Production at the LHC

TL;DR

This paper investigates how the potential compositeness of the right-handed top-quark influences Higgs boson production at the LHC through dimension-six operators, finding some operators can significantly alter production rates.

Contribution

It identifies the dominant dimension-six operators arising from top-quark compositeness and analyzes their impact on Higgs production, highlighting the operator that can notably change the cross section.

Findings

The (V+A)⊗(V+A) four-top contact interaction does not affect gluon fusion Higgs production at lowest order.

Operators involving two t_R's and two Higgs doublets can significantly modify the Higgs production cross section.

The effects are most notable if the cutoff scale is around 1 TeV.

Abstract

Motivated by the possibility that the right-handed top-quark (t_R) is composite, we discuss the effects of dimension-six operators on the Higgs boson production at the LHC. When t_R is the only composite particle among the Standard Model (SM) particles, the (V+A)\otimes (V+A) type four-top-quark contact interaction is expected to have the largest coefficient among the dimension-six operators, according to the Naive Dimensional Analysis (NDA). We find that, to lowest order in QCD and other SM interactions, the cross section of the SM Higgs boson production via gluon fusion does not receive corrections from one insertion of the new contact interaction vertex. We also discuss the effects of other dimension-six operators whose coefficients are expected to be the second and the third largest from NDA. We find that the operator which consists of two t_R's and two SM Higgs boson doublets can recognizably change the Higgs boson production cross section from the SM prediction if the cut-off scale is \sim 1TeV.