Sensitivity to new physics: single-Higgs couplings vs. the trilinear Higgs coupling

TL;DR

This paper emphasizes the importance of measuring the trilinear Higgs coupling at future colliders to detect BSM physics, highlighting models where deviations occur without affecting other Higgs observables.

Contribution

It discusses BSM scenarios with significant deviations in the trilinear Higgs coupling while other observables stay SM-like, stressing the need for precise future measurements.

Findings

Certain BSM models predict large deviations in the trilinear Higgs coupling.

Other Higgs observables remain close to SM predictions in these models.

Precise measurement of the trilinear coupling is crucial for probing BSM physics.

Abstract

The trilinear Higgs self-coupling provides a unique probe of the structure of the Higgs potential and of the nature of the electroweak phase transition, and constitutes a key target for future collider experiments. Recent studies have shown that confronting theoretical predictions for the trilinear Higgs coupling with current experimental bounds offers a powerful and complementary way to test effects of physics beyond the Standard Model (BSM), in particular those arising from extended Higgs sectors. Meanwhile, substantial progress has been achieved in the precise calculation and automation of the trilinear Higgs coupling in a wide class of BSM models. This contribution discusses several BSM scenarios, compatible with existing constraints, in which sizeable deviations in the trilinear Higgs coupling w.r.t. the Standard Model (SM) value are predicted, while other Higgs observables remain close to their SM expectations and are therefore difficult to probe experimentally. These results highlight the strong physics motivation for a precise measurement of the trilinear Higgs coupling at a future Higgs factory.