Search for invisible decays of a Higgs boson produced via vector boson fusion at $\sqrt{s}=13$ TeV.

A search for invisible decays of a Higgs boson produced via vector boson fusion has been performed in the 13 TeV dataset collected by CMS in 2015. The dataset corresponds to an integrated luminosity of 2.30~fb$^{-1}$. A dedicated trigger is used to select events with a jet pair compatible with vector boson fusion production of a Higgs boson, together with missing energy from its invisible decay. The offline selection makes further use of the event topology. Backgrounds arise from $Z(\nu\nu)+\mathrm{jets}$ and $W(l\nu)+\mathrm{jets}$ in which the charged lepton is unidentified, and QCD multijet production. Signal and background yields are extracted from a simultaneous fit to the signal region and multiple control regions. Minor backgrounds from diboson and top-quark processes are estimated from Monte-Carlo simulation. The observed (expected) upper limit on the invisible branching fraction of the 125 GeV Higgs boson is found to be 69\% (62\%), assuming the Standard Model production cross section. These upper limits improve to 32\% (26\%) when combined with previous 8 TeV results and a search for Higgs bosons decaying to invisible particles in the $Z(ll)H$ channel at 13 TeV.