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T: Fachverband Teilchenphysik

T 75: Higgs Physics VII

T 75.4: Vortrag

Donnerstag, 19. März 2026, 17:00–17:15, KH 01.019

Assessing uncertainties in the determination of the trilinear Higgs self-coupling from single-Higgs observables — Henning Bahl¹, Philip Bechtle², Johannes Braathen³, Sven Heinemeyer⁴, Jenny List³, •Murillo Vellasco², and Georg Weiglein^3,5 — ¹Institute for Theoretical Physics (ITP), Universität Heidelberg, Germany — ²Physikalisches Institut, Universität Bonn, Germany — ³Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany — ⁴Instituto de Física Teórica (UAM/CSIC), Universidad Autónoma de Madrid, Spain — ⁵Institut für Theoretische Physik, Universität Hamburg, Germany

Probing the nature of the Higgs potential is a primary objective of the next generation of flagship particle physics experiments, for which measuring λ_hhh, the trilinear Higgs self-coupling, will play a crucial role. Despite operating below the di-Higgs production threshold, circular e⁺e⁻ machines will still have indirect access to λ_hhh via its loop-level contributions to single-Higgs production observables. In this work, we investigate how well λ_hhh can be determined by such indirect effects within a global EFT fit. While most studies to date assume that future measurements will be compatible with SM predictions, here we consider non-SM values of λ_hhh, using an inert doublet extension of the SM as an example of a New Physics scenario that could be realised in nature. We find that theory uncertainties related to the truncation of the EFT expansion and to higher-order corrections, which are often neglected, can have a substantial impact on the resulting precision for λ_hhh.

Keywords: future colliders; Higgs; self-coupling; SMEFT; theory uncertainties