Probing the littlest Higgs model with $T$ parity using di-Higgs events through $Z_H$-pair production at the LHC in NLO QCD

TL;DR

This paper studies di-Higgs events from $Z_H$-pair production at the LHC within the littlest Higgs model with $T$ parity, including NLO QCD corrections, to improve detection prospects and reduce theoretical uncertainties.

Contribution

It provides the first detailed NLO QCD analysis of $Z_H$-pair production in the littlest Higgs model with $T$ parity, including $gg$-fusion effects and decay distributions.

Findings

QCD corrections slightly reduce scale uncertainty.

Enhanced kinematic distributions improve signal detection.

Proper cuts can distinguish signal from background.

Abstract

We investigate the di-Higgs events through $Z_H$-pair production at the CERN Large Hadron Collider including the pure next-to-leading order (NLO) QCD correction and the $gg$-fusion contribution in the framework of the littlest Higgs model with $T$ parity. We employ the diagram subtraction scheme in the QCD NLO calculations to avoid double counting and keep the convergence of the perturbative QCD description for the $Z_H$-pair production. We investigate the dependence of the leading order and QCD corrected integrated cross sections on the renormalization/factorization scale, and find that the total QCD corrections slightly reduce the scale uncertainty in the plotted range. By considering the subsequent decays of the intermediately produced $Z_H$ bosons and adopting the exclusive four-$b$-jet event selection criterion, the QCD correction provides considerable enhancement of the kinematic distributions for final decay products. We find that it is possible to select the signature of the $Z_H$-pair production from possible standard model background by taking proper kinematic cuts.