Search for invisible Higgs boson decays in vector boson fusion at $\sqrt{s} = 13$ TeV with the ATLAS detector

TL;DR

This paper searches for invisible decays of the Higgs boson produced via vector boson fusion at 13 TeV using ATLAS data, setting limits on decay rates and WIMP interactions.

Contribution

It provides the first limits on invisible Higgs decays in VBF production at 13 TeV and interprets results within Higgs portal models.

Findings

Observed events are consistent with background expectations.

Upper limit on Higgs invisible decay branching ratio is 0.37 at 95% CL.

Limits on cross section times branching fraction for additional scalars up to 3 TeV.

Abstract

We report a search for Higgs bosons that are produced via vector boson fusion and subsequently decay into invisible particles. The experimental signature is an energetic jet pair with invariant mass of $\mathcal{O}(1) $ TeV and $\mathcal{O}(100) $ GeV missing transverse momentum. The analysis uses 36.1 fb$^{-1}$ of $pp$ collision data at $\sqrt{s}=13$ TeV recorded by the ATLAS detector at the LHC. In the signal region the 2252 observed events are consistent with the background estimation. Assuming a 125 GeV particle with Standard Model cross sections, the upper limit on the branching fraction of the Higgs boson decay into invisible particles is 0.37 at 95% CL where 0.28 was expected. This limit is interpreted in Higgs portal models to set limits on the WIMP-nucleon scattering cross section. We also consider invisible decays of additional scalar bosons with masses up to 3 TeV for which the upper limits on the cross section times branching fraction are in the range of $0.3-1.7$ pb.