Experimental searches for tHq

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.