Gauge-independent Renormalization of the N2HDM

TL;DR

This paper develops a gauge-independent renormalization scheme for the N2HDM, enabling precise predictions of Higgs observables crucial for interpreting LHC data and exploring beyond-the-Standard Model physics.

Contribution

It introduces a complete gauge-independent renormalization scheme for the N2HDM, including mixing angles and key parameters, facilitating accurate higher-order calculations.

Findings

Renormalization scheme applied to Higgs decay processes.

Corrections to Higgs observables can be sizeable.

Scheme improves reliability of theoretical predictions.

Abstract

The Next-to-Minimal 2-Higgs-Doublet Model (N2HDM) is an interesting benchmark model for a Higgs sector consisting of two complex doublet and one real singlet fields. Like the Next-to-Minimal Supersymmetric extension (NMSSM) it features light Higgs bosons that could have escaped discovery due to their singlet admixture. Thereby, the model allows for various different Higgs-to-Higgs decay modes. Contrary to the NMSSM, however, the model is not subject to supersymmetric relations restraining its allowed parameter space and its phenomenology. For the correct determination of the allowed parameter space, the correct interpretation of the LHC Higgs data and the possible distinction of beyond-the-Standard Model Higgs sectors higher order corrections to the Higgs boson observables are crucial. This requires not only their computation but also the development of a suitable renormalization scheme. In this paper we have worked out the renormalization of the complete N2HDM and provide a scheme for the gauge-independent renormalization of the mixing angles. We discuss the renormalization of the $\mathbb{Z}_2$ soft breaking parameter $m_{12}^2$ and the singlet vacuum expectation value $v_S$. Both enter the Higgs self-couplings relevant for Higgs-to-Higgs decays. We apply our renormalization scheme to different sample processes such as Higgs decays into $Z$ bosons and decays into a lighter Higgs pair. Our results show that the corrections may be sizeable and have to be taken into account for reliable predictions.