Higgs pair production in the 2HDM: impact of loop corrections to the trilinear Higgs couplings and interference effects on experimental limits

S. Heinemeyer; M. Mühlleitner; K. Radchenko; G. Weiglein

doi:10.1140/epjc/s10052-025-14124-x

2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2025) 85: 437
https://doi.org/10.1140/epjc/s10052-025-14124-x

Regular Article - Theoretical Physics

Higgs pair production in the 2HDM: impact of loop corrections to the trilinear Higgs couplings and interference effects on experimental limits

S. Heinemeyer¹, M. Mühlleitner², K. Radchenko³^a and G. Weiglein³^,4

¹ Instituto de Física Teórica (UAM/CSIC), Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
² Institute for Theoretical Physics, Karlsruhe Institute of Technology, 76128, Karlsruhe, Germany
³ Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
⁴ II. Institut für Theoretische Physik, Universität Hamburg, Luruper Chaussee 149, 22761, Hamburg, Germany

^a kateryna.radchenko@desy.de

Received: 18 July 2024
Accepted: 26 March 2025
Published online: 18 April 2025

Abstract

The results obtained at the LHC for constraining the trilinear Higgs self-coupling of the detected Higgs boson at about 125 GeV, $λ_{hhh}$ $\lambda _{hhh}$ , via the Higgs pair production process have significantly improved during the last years. We investigate the impact of potentially large higher-order corrections and interference effects on the comparison between the experimental results and the theoretical predictions for the pair production of the 125 GeV Higgs boson at the LHC. We use the theoretical framework of the Two Higgs Doublet Model (2HDM), containing besides the SM-like $C P$ ${\mathcal{C}\mathcal{P}}$ -even Higgs boson h a second $C P$ ${\mathcal{C}\mathcal{P}}$ -even Higgs boson H, which we assume to be heavier, $m H > m h$ $$mH > mh$$ . We analyze in particular the invariant mass distribution of the two produced Higgs bosons and show that the loop corrections to the trilinear Higgs couplings $λ_{hhh}$ $\lambda _{hhh}$ and $λ_{hhH}$ $\lambda _{hhH}$ as well as interference contributions give rise to important effects both for the differential and the total cross section. We point out the implications for the experimental limits that can be obtained in the 2HDM for the case of the resonant production of the heavy Higgs boson H. We emphasize the importance of the inclusion of interference effects between resonant and non-resonant contributions in the experimental analysis for a reliable determination of exclusion bounds for a heavy resonance of an extended Higgs sector.

© The Author(s) 2025

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.