Two-loop corrections to the Higgs trilinear coupling in BSM models with classical scale invariance

Abstract

Classical scale invariance (CSI) is an attractive concept for BSM model building, explaining the apparent alignment of the Higgs sector and potentially relating to the hierarchy problem. Furthermore, a particularly interesting feature is that the Higgs trilinear coupling ${\lambda }_{hhh}$ is universally predicted at one loop in CSI models, and deviates by 67% from its (tree-level) SM prediction. This result is however modified at two loops, and we review in these proceedings our calculation of leading two-loop corrections to ${\lambda }_{hhh}$ in models with classical scale invariance, taking as an example a CSI scenario of a Two-Higgs-Doublet Model. We find that the inclusion of two-loop effects allows distinguishing different scenarios with CSI, although the requirement of reproducing the known 125-GeV Higgs-boson mass severely restricts the allowed values of ${\lambda }_{hhh}$.

Talk presented at the International Workshop on Future Linear Colliders (LCWS2021), 15-18 March 2021. C21-03-15.1. 10 pages, 3 figures