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

TL;DR

This paper calculates leading two-loop corrections to the Higgs trilinear coupling in models with classical scale invariance, showing how these effects refine predictions and help distinguish different CSI scenarios.

Contribution

It provides the first detailed two-loop correction analysis of the Higgs trilinear coupling in CSI models, specifically within a Two-Higgs-Doublet Model framework.

Findings

Two-loop effects modify the Higgs trilinear coupling predictions.

Reproducing the 125-GeV Higgs mass constrains the coupling values.

Two-loop corrections can differentiate CSI scenarios.

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 $\lambda_{hhh}$.