Single top partner production in the Higgs to diphoton channel in the Littlest Higgs Model with T-parity

Ning Liu,Lei Wu,Bingfang Yang,Mengchao Zhang

doi:10.1016/j.physletb.2015.12.066

Abstract

The top partner as a hallmark of the Littlest Higgs Model with T-parity (LHT model) has been extensively searched for during the Large Hadron Collider (LHC) Run-1. With the increasing mass limits on the top partner, the single production of the top partner will be dominant over the pair production. Under the constraints from the Higgs data, the electroweak precision observables and Rb, we find that the mass of T-even top partner (T+) has to be heavier than 730 GeV. Then, we investigate the observability of the single T-even top partner production through the process pp→T+j with the sequent decay T+→th in the di-photon channel in the LHT model at the LHC. We find that the mass of T+ can be excluded up to 800 GeV at 2σ level at 14 TeV LHC with the integrated luminosity L=3 ab−1.

Highlights

The top partner as a hallmark of the Littlest Higgs model with T -parity (LHT model) has been extensively searched for during the Large Hadron Collider (LHC) Run-1
Under the constraints from the Higgs data, the electroweak precision observables and Rb, we find that the mass of T -even top partner (T+) has to be heavier than 730 GeV
We find that the mass of T+ can be excluded up to 800 GeV at 2σ level at 14 TeV LHC with the integrated luminosity L = 3 ab−1

Summary

TOP PARTNER IN LITTLEST HIGGS MODEL WITH T-PARITY

The LHT model is a non-linear σ model based on the coset space SU (5)/SO(5). For the top quark sector of LHT model, two singlet fields TL1 and TL2 The T -even Dirac fermion T+ ≡ (TL+, TR+), is responsible for canceling the quadratic divergence to the Higgs mass induced by the top quark loop. Both T+ and T− acquire a mass of order f from a Yukawa-like Lagrangian. From Eq 6, we can see that the T -even top partner is always heavier than the T -odd heavy top partner, but it has more interesting phenomenological signatures due to the complicated decay modes It is directly related with the electroweak naturalness of the LHT model.

CONSTRAINTS ON THE LHT MODEL

CONCLUSION