Higgs Pair Production as a Signal of Enhanced Yukawa Couplings

TL;DR

This paper explores how in two Higgs doublet models with a flavour symmetry, enhanced Higgs-fermion couplings correlate with increased Higgs pair production, offering new experimental search strategies at the LHC.

Contribution

It identifies parameter regions where enhanced Yukawa couplings lead to increased Higgs pair production, linking flavour symmetry, coupling modifications, and collider phenomenology.

Findings

Enhanced Yukawa couplings can significantly increase Higgs pair production cross section.

Both resonant and non-resonant contributions are affected by the coupling enhancements.

Differential distribution analyses can serve as indirect probes of light fermion Higgs couplings.

Abstract

We present a non-trivial correlation between the enhancement of the Higgs-fermion couplings and the Higgs pair production cross section in two Higgs doublet models with a flavour symmetry. This symmetry suppresses flavour-changing neutral couplings of the Higgs boson and allows for a partial explanation of the hierarchy in the Yukawa sector. After taking into account the constraints from electroweak precision measurements, Higgs coupling strength measurements, and unitarity and perturbativity bounds, we identify an interesting region of parameter space leading to enhanced Yukawa couplings as well as enhanced di-Higgs gluon fusion production at the LHC reach. This effect is visible in both the resonant and non-resonant contributions to the Higgs pair production cross section. We encourage dedicated searches based on differential distributions as a novel way to indirectly probe enhanced Higgs couplings to light fermions.