Hiding the Higgs Boson from Prying Eyes

There are two simple ways that the Higgs boson H of the Standard Model (SM) may be more difficult to observe than expected at the Large Hadron Collider (LHC) or the Tevatron. One is well-known, i.e. H decays invisibly, into dark-matter scalar particles for example. The other is that H mixes with a heavy singlet scalar S which couples to new colored fermions and scalars. Of the two mass eigenstates, the lighter one could (accidentally) have a suppressed effective coupling to two gluons, and the heavy one could be kinematically beyond the reach of the LHC.