Double Higgs boson production as an exclusive probe for a sequential fourth generation with wrong-sign Yukawa couplings

Md Raju,Dipankar Das,Anirban Kundu,Jyoti Prasad Saha

doi:10.1103/physrevd.101.055036

Abstract

It has been shown that the data from the Large Hadron Collider (LHC) does not rule out a chiral sequential fourth generation of fermions that obtain their masses through an identical mechanism as the other three generations do. However, this is possible only if the scalar sector of the Standard Model is suitably enhanced, like embedding it in a type-II two-Higgs doublet model. In this article, we try to show that double Higgs production (DHP) can unveil the existence of such a hidden fourth generation in a very efficient way. While the DHP cross-section in the SM is quite small, it is significantly enhanced with a fourth generation. We perform a detailed analysis of the dependence of the DHP cross-section on the model parameters, and show that either a positive signal of DHP is seen in the early next run of the LHC, or the model is ruled out.

Highlights

More than seven years after the discovery of the Higgs boson at the LHC [1,2], the data have reached such a level of precision so as to vindicate the Standard Model (SM) [3] and to rule out a number of theories beyond the SM
We perform a detailed analysis of the dependence of the double Higgs production (DHP) cross section on the model parameters and show that either a positive signal of DHP is seen in the early run of the LHC or the model is ruled out
We perfporffimffi the analysis of DHP within the framework of xSM4 for s 1⁄4 14 TeV and show that (i) there should be a substantial enhancement of the DHP cross section, compared to that in the SM, which should either result in a positive signal very soon or rule the model out, and (ii) on top of the enhancement due to the fourth generation of fermions, there is a further contribution from the heavy neutral Higgs of 2HDM, the effect of which results in a severe constraint on the parameter space of 2HDM associated with xSM4

Summary

INTRODUCTION

More than seven years after the discovery of the Higgs boson at the LHC [1,2], the data have reached such a level of precision so as to vindicate the Standard Model (SM) [3] and to rule out a number of theories beyond the SM. We perfporffimffi the analysis of DHP within the framework of xSM4 for s 1⁄4 14 TeV and show that (i) there should be a substantial enhancement of the DHP cross section, compared to that in the SM, which should either result in a positive signal very soon or rule the model out, and (ii) on top of the enhancement due to the fourth generation of fermions, there is a further contribution from the heavy neutral Higgs of 2HDM, the effect of which results in a severe constraint on the parameter space of 2HDM associated with xSM4 At this point, one must point out the inherent limitations of such a study.

Double Higgs production in the SM

DOUBLE HIGGS PRODUCTION IN xSM4

OBSERVABILITY OF xSM4

Findings

CONCLUSION