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 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. 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. *

Evasive maneuvers for a sequential fourth generation to circumvent the Higgs data

“…Since the box diagram dominates the gg → hh amplitude, the production cross-section will be enhanced roughly by a factor of 9. Such a huge enhancement implies that either a positive signal of di-Higgs production is seen in the early next run of the LHC, or the model is ruled out [29].…”

Disentangling new physics effects on non-resonant Higgs boson pair production from gluon fusion

“…The second is non-SM Higgs trilinear self-coupling [18][19][20][21], parameterized by the Higgs coupling modifier κ λ ≡ λ hhh /λ SM hhh . The third is to introduce new colored particles in the triangle and box diagrams [22][23][24][25][26][27][28][29][30]. 1 Since resonant Higgs boson pair production can be identified through a peak in the distribution of the invariant mass of the Higgs boson pair, experimentalists usually present the di-Higgs results in two modes, non-resonant and resonant ones [35,36].…”