Direct detection of Higgs-portal dark matter at the LHC

TL;DR

This paper investigates how monojet searches at the LHC can constrain the invisible decay of the Higgs boson, providing new limits on Higgs-portal dark matter models and comparing direct and indirect detection methods.

Contribution

It demonstrates that current LHC monojet data already set significant limits on invisible Higgs decays and discusses future improvements and implications for dark matter detection.

Findings

95% CL limit on invisible Higgs decay rate is comparable to Standard Model Higgs production

Monojet searches can be significantly improved with more data and reduced systematics

LHC constraints strongly limit dark matter-nucleon scattering cross sections in Higgs portal models

Abstract

We consider the process in which a Higgs particle is produced in association with jets and show that monojet searches at the LHC already provide interesting constraints on the invisible decays of a 125 GeV Higgs boson. Using the existing monojet searches performed by CMS and ATLAS, we show the 95% confidence level limit on the invisible Higgs decay rate is of the order of the total Higgs production rate in the Standard Model. This limit could be significantly improved when more data at higher center of mass energies are collected, provided systematic errors on the Standard Model contribution to the monojet background can be reduced. We also compare these direct constraints on the invisible rate with indirect ones based on measuring the Higgs rates in visible channels. In the context of Higgs portal models of dark matter, we then discuss how the LHC limits on the invisible Higgs branching fraction impose strong constraints on the dark matter scattering cross section on nucleons probed in direct detection experiments.