Invisible Higgs decay at the Large Hadron-Electron Collider

The possibility that the 125 GeV Higgs boson may decay into invisible non-standard-model (non-SM) particles is theoretically and phenomenologically intriguing. In this paper, we investigate the sensitivity of the Large Hadron Electron Collider (LHeC) to an invisibly decaying Higgs, in its proposed high-luminosity running mode. We focus on the neutral current Higgs production channel which offers more kinematical handles than its charged current counterpart. The signal contains one electron, one jet, and large missing energy. With a cut-based parton-level analysis, we estimate that if the hZZ coupling is at its standard model (SM) value, then assuming an integrated luminosity of 1 ab(-1), the LHeC with the proposed 60 GeV electron beam (with -0.9 polarization) and 7 TeV proton beam is capable of probing Br (h -> is not an element of(T)) = 6% at 2 sigma level. Good lepton veto performance (especially hadronic tau veto) in the forward region is crucial to the suppression of the dominant W je background. We also explicitly point out the important role that may be played by the LHeC in probing a wide class of exotic Higgs decay processes and emphasize the general function of lepton-hadron colliders in the precision study of new resonances after their discovery in hadron-hadron collisions.