Analysis of Top Quark Pair Production Signal from Neutral 2HDM Higgs Bosons at LHC

Majid Hashemi,Mahbobeh Jafarpour

doi:10.1155/2018/4038243

Abstract

In this paper, the top quark pair production events are analyzed as a source of neutral Higgs bosons of the two Higgs doublet model type I at LHC. The production mechanism is pp→H/A→tt¯ assuming a fully hadronic final state through t→Wb→jjb. In order to distinguish the signal from the main background which is the standard model tt¯, we benefit from the fact that the top quarks in signal events acquire large Lorentz boost due to the heavy neutral Higgs boson. This feature leads to three collinear jets (a fat jet) which is a discriminating tool for identification of the top quarks from the Higgs boson resonances. Events with two identified top jets are selected and the invariant mass of the top pair is calculated for both signal and background. It is shown that the low tan β region has still some parts which can be covered by this analysis and has not yet been excluded by flavor physics data.

Highlights

The standard model (SM) of particle physics has taken a major step forward by observing the Higgs boson at LHC [1, 2] based on a theoretical framework known as the Higgs mechanism [3,4,5,6,7,8]
The current study focuses on H/A 󳨀→ tt with branching ratio being near unity and independent of the Higgs boson mass (Figure 1) and tan β (Figure 2)
Extra sources of tt events from what we expect from standard model can appear from theories beyond standard model such as two Higgs doublet models

Summary

Introduction

The standard model (SM) of particle physics has taken a major step forward by observing the Higgs boson at LHC [1, 2] based on a theoretical framework known as the Higgs mechanism [3,4,5,6,7,8]. The supersymmetry provides an elegant solution to the gauge coupling unification, dark matter candidate, and the Higgs boson mass radiative correction by a natural parameters tuning. In such a model two Higgs doublets are required to give mass to the double space of the particles [12,13,14]. The analysis uses the top tagging algorithm to identify two top jets in the final state; before going to that step, two selection cuts are applied to purify the signal sample.

Objectives

Discussion

Conclusion