# Combination of searches for invisible Higgs boson decays with the ATLAS experiment

## TL;DR

This paper combines multiple ATLAS searches for invisible Higgs decays to improve constraints on dark matter production, setting the most stringent limits to date on the Higgs invisible branching ratio.

## Contribution

It presents a novel statistical combination of different Higgs decay channels at multiple energies, enhancing sensitivity to invisible decays.

## Key findings

- Excludes Higgs invisible branching ratio above 0.26 at 95% CL
- Combines data from 7, 8, and 13 TeV collisions for improved limits
- Sets the most stringent constraints on Higgs invisible decays to date

## Abstract

Dark matter particles, if sufficiently light, may be produced in decays of the Higgs boson. This Letter presents a statistical combination of searches for $H\to\textrm{invisible}$ decays where $H$ is produced according to the Standard Model via vector boson fusion, $Z(\ell\ell)H$, and $W\!/\!Z(\textrm{had})H$, all performed with the ATLAS detector using 36.1 fb$^{-1}$ of $pp$ collisions at a center-of-mass energy of $\sqrt s = 13$ TeV at the LHC. In combination with the results at $\sqrt s = 7$ and 8 TeV, an exclusion limit on the $H\to\textrm{invisible}$ branching ratio of $0.26 (0.17^{+0.07}_{-0.05})$ at 95% confidence level is observed (expected).