C1 and $K_{EW}$ factors parametrization in STXS bins for constraining the Higgs boson self-coupling

Higgs pair production processes provide the direct probe to the Higgs boson self-coupling ($\lambda_{3}$). However, as well known such a processes have a small production cross section. It is also known that single Higgs processes indirectly depends on $\lambda_{3}$, thus an alternative method to measure the $\lambda_{3}$ is considering $\lambda_{3}$-dependent NLO EW corrections in single Higgs processes. The magnitude of these corrections are encoded by some process and kinematic-dependent coefficients named as C1. In the following, an overview of the parametrization of the C1 coefficients and K-factors in STXS bins performed by ATLAS and CMS are shown.