A Study of the Single Higgs Modelling for Constraining Higgs Boson Trilinear Self-coupling in STXS (1.2) Measurements

This document provides a parametrization of the cross sections of the main Higgs boson (H) production modes as a function of the H trilinear self-coupling, $\lambda$, with the phase-space granularity defined by the simplified template cross section (STXS) framework at stage 1.2. The trilinear self-coupling of the Higgs boson is an important parameter in the standard model, which is weakly constrained by current measurements. The coupling $\lambda$ can be probed indirectly by measurementing the main H production mode cross sections with high precision. Next-to-leading order electroweak corrections which depend on $\lambda$ can affect both the inclusive and the differential H cross sections. Therefore, the differential information available in STXS stage 1.2 measurements can be exploited to further improve the constraints on $\lambda$. The constraints on $\lambda$ achieved with this method are comparable and complementary to the constraints from searches for Higgs boson pair production.