  Given its weak coupling to bottom quarks and tau leptons, the Higgs boson may
predominantly decay into invisible particles like gravitinos, neutralinos, or
gravitons. We consider the manifestation of such an invisibly decaying Higgs
boson in weak boson fusion at the CERN LHC. Distinctive kinematic distributions
of the two quark jets of the signal as compared to Zjj and Wjj backgrounds
allow to restrict the Higgs branching ratio to 'invisible' final states to some
13% with 10fb^{-1} of data, provided events with two energetic forward jets of
high dijet invariant mass and with substantial missing transverse momentum can
be triggered efficiently. It is also possible to discover these particles with
masses up to 480 GeV in weak boson fusion, at the 5 sigma level, provided their
invisible branching ratio is close to 100%.
