# Resolving the degeneracy in top quark Yukawa coupling with Higgs pair production

## TL;DR

This paper investigates how Higgs pair production at high-energy colliders can disentangle the effects of different dimension-six operators modifying the top quark Yukawa coupling, providing clearer insights into new physics beyond the Standard Model.

## Contribution

It demonstrates that combining multiple Higgs production channels can resolve degeneracies in Wilson coefficients affecting the top Yukawa coupling at future colliders.

## Key findings

- Higgs pair production constrains $c_y$ at 100 TeV colliders.
- Combining single and double Higgs production separates contributions of $c_H$ and $c_y$.
- Different models' predictions for $c_y$ and $c_t$ can be distinguished.

## Abstract

The top quark Yukawa coupling ($y_t$) can be modified by two dimension-six operators $\mathcal{O}_H$ and $\mathcal{O}_y$ with the corresponding Wilson coefficients $c_H$ and $c_y$, whose individual contribution cannot be distinguished by measuring $y_t$ alone. However, such a degeneracy can be resolved with Higgs boson pair production. In this work we explore the potential of resolving the degeneracy of the unknown Wilson coefficients $c_H$ and $c_y$ at the 14~TeV LHC and the 100~TeV hadron colliders. Combining the information of the single Higgs production, $t\bar{t}h$ associated production and Higgs pair production, the individual contribution of $c_H$ and $c_y$ to $y_t$ can be separated. Regardless of the value of $c_H$, the Higgs pair production can give a strong constraint on $c_y$ at the 100 TeV hadron collider. We further show that it is possible to differentiate various $c_y$ and $c_t$ values predicted in several benchmark models.