One-loop Corrections to the Higgs Boson Invisible Decay in the Dark Doublet Phase of the N2HDM

TL;DR

This paper calculates NLO electroweak corrections to the Higgs decay into dark matter in the N2HDM model, showing current measurements do not constrain the model but future precision might.

Contribution

It provides the first calculation of NLO electroweak corrections to Higgs invisible decay in the N2HDM dark doublet phase, assessing their impact on experimental constraints.

Findings

Current Higgs invisible decay measurements do not constrain the model.

NLO corrections are not large enough to impose new limits.

Future precision measurements could potentially constrain the model.

Abstract

The Higgs invisible decay width may soon become a powerful tool to probe extensions of the Standard Model with dark matter candidates at the Large Hadron Collider. In this work, we calculate the next-to-leading order (NLO) electroweak corrections to the 125 GeV Higgs decay width into two dark matter particles. The model is the next-to-minimal 2-Higgs-doublet model (N2HDM) in the dark doublet phase, that is, only one doublet and the singlet acquire vacuum expectation values. We show that the present measurement of the Higgs invisible branching ratio, BR$(H \to$ invisible $< 0.11$), does not lead to constraints on the parameter space of the model at leading order. This is due to the very precise measurements of the Higgs couplings but could change in the near future. Furthermore, if NLO corrections are required not to be unphysically large, no limits on the parameter space can be extracted from the NLO results.