Contributor info: Dr Henning Bahl

Henning Bahl, Elina Fuchs, Marc Hannig, Marco Menen

SciPost Phys. Core 8, 006 (2025) · published 20 January 2025 | Toggle abstract · pdf

The Higgs-gluon interaction is crucial for LHC phenomenology. To improve the constraints on the $\mathcal{CP}$ structure of this coupling, we investigate Higgs production with two jets using machine learning. In particular, we exploit the $\mathcal{CP}$ sensitivity of the so far neglected phase space region that differs from the typical vector boson fusion-like kinematics. Our results indicate that further improvements in the current experimental limits could be achievable using our techniques. We also discuss the most relevant observables and how $\mathcal{CP}$ violation in the Higgs–gluon interaction can be disentangled from $\mathcal{CP}$ violation in the interaction between the Higgs boson and massive vector bosons. Assuming the absence of $\mathcal{CP}$-violating Higgs interactions with coloured beyond-the-Standard-Model states, our projected limits on a $\mathcal{CP}$-violating top-Yukawa coupling are competitive with more direct probes like top-associated Higgs production and limits from a global fit.

Henning Bahl

SciPost Phys. Proc. 8, 010 (2022) · published 11 July 2022 | Toggle abstract · pdf

Precision measurements of top-associated Higgs production are an important ingredient to unravel the $\mathcal{CP}$ nature of the Higgs boson. In this work, we constraint the $\mathcal{CP}$ nature of the top-Yukawa coupling taking into account all relevant inclusive and differential Higgs boson measurements. Based upon this fit, we show that it is crucial to disentangle single- and di-top-associated Higgs production for tightening indirect constraints on a $\mathcal{CP}$-odd top-Yukawa coupling in the future. In this context, we propose an analysis strategy for measuring $tH$ production at the HL-LHC without relying on assumptions about the Higgs $\mathcal{CP}$ character.