One-loop Corrections to the Higgs Boson Invisible Decay in a Complex Singlet Extension of the SM

TL;DR

This paper calculates one-loop electroweak corrections to the Higgs boson's invisible decay into dark matter in a complex singlet extension of the Standard Model, showing these corrections are crucial for future precision measurements.

Contribution

It provides the first detailed calculation of electroweak one-loop corrections to Higgs invisible decay in this model, highlighting their importance for experimental constraints.

Findings

Corrections are stable and of the order of a few percent.

Current Higgs invisible decay limits constrain the model's parameter space.

Electroweak corrections will be essential for future LHC measurements.

Abstract

The search for dark matter (DM) at colliders is founded on the idea of looking for something invisible. There are searches based on production and decay processes where DM may reveal itself as missing energy. If nothing is found, our best tool to constrain the parameter space of many extensions of the Standard Model (SM) with a DM candidate is the Higgs boson. As the measurements of the Higgs couplings become increasingly precise, higher-order corrections will start to play a major role. The tree-level contribution to the invisible decay width provides information about the portal coupling. Higher-order corrections also gives us access to other parameters from the dark sector of the Higgs potential that are not present in the tree-level amplitude. In this work we will focus on the complex singlet extension of the SM in the phase with a DM candidate. We calculate the one-loop electroweak corrections to the decay of the Higgs boson into two DM particles. We find that the corrections are stable and of the order of a few percent. The present measurement of the Higgs invisible branching ratio, BR$(H \to$ invisible $) < 0.11$, already constrains the parameter space of the model at leading order. We expect that by the end of the LHC the experimental measurement will require the inclusion of the electroweak corrections to the decay in order to match the experimental accuracy. Furthermore, the only competing process, which is direct detection, is shown to have a cross section below the neutrino floor.