Experimental searches for tHq

TL;DR

This paper reviews recent experimental searches for the associated production of a Higgs boson and a single top quark (tHq) at the LHC, focusing on how these searches probe the top Yukawa coupling's magnitude and sign, which could indicate new physics.

Contribution

It summarizes the latest results from ATLAS and CMS on tHq production, highlighting their different approaches to constrain the top Yukawa coupling and its potential deviations.

Findings

ATLAS and CMS set upper limits on tHq production cross section.

Results constrain the magnitude and sign of the top Yukawa coupling.

Recent data improves sensitivity to deviations in Higgs-top interactions.

Abstract

The Yukawa coupling of the Higgs boson to top quarks $\text{Y}_\text{t}$ is of particular interest as the top quark plays a special role in the electroweak symmetry breaking mechanism. Any deviation from its predicted value could hint at new physics. For this investigation the associated production of a Higgs boson and a single top quark (tHq) is a promising channel. Due to interference terms in the production amplitude the cross section $\sigma_\text{tHq}$ is not only sensitive to the magnitude of $\text{Y}_\text{t}$ but also to its sign making this channel special. In addition the branching ratio BR($\text{H}\to\gamma\gamma$) is sensitive to sign and magnitude of $\text{Y}_\text{t}$. The ATLAS and CMS collaborations exploit both effects to set upper limits on $\sigma_\text{tHq}$ and the deviation of $\text{Y}_\text{t}$ by applying inherently different approaches. The most recent results from both collaborations using the full data provided by the LHC are presented.