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

Abstract

It has been shown that the data from the LHC do 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.