Higgs boson decays to quarkonia and the Hc̄c coupling

In this paper we discuss decays of the Higgs boson to quarkonia in association with a photon. We identify a new mechanism for producing such final states in Higgs decays that leads to predictions for the decay rates that differ by an order of magnitude from previous estimates. Although the branching ratios for these processes are still small, the processes are experimentally clean, and the H→J/ψγ decay should be observable at a 14 TeV LHC. We point out that quantum interference between two different production mechanisms makes the decay rates sensitive to the HQ̄Q couplings. Consequently, measurements of the H→J/ψγ decay rate would allow one to probe the Higgs-charm coupling directly at the LHC. We discuss the experimental prospects for the observation of these decays and for the direct measurement of the Hc̄c coupling.