Two-loop QCD corrections to Higgs radiative decay to vector quarkonium

The exclusive production of J/ψ through Higgs boson radiative decay may serve a clean channel to extracting the charm quark Yukawa coupling. We calculate the two-loop QCD corrections to H→ J/ψ(Υ)+γ using an optimized nonrelativistic QCD (NRQCD) approach. We compute the O(αₛ²) correction in the direct channel, where Higgs directly couples to cc̄, as well as the O(αₛ) correction in the indirect channel, { viz.}, H→γ^*γ followed by the virtual photon fragmentation into J/ψ. Incorporating the destructive interference between the direct and indirect channels, we present to date the most accurate predictions for Higgs boson radiative decay into vector quarkonium, B(H→ J/ψ+γ) = 3.27-0.07+0.30+0.06-0.06-0.13+0.13× 10⁻⁶, and B(H→ Υ+γ)= 1.34-0.31+0.75+0.25-0.20+0.05-0.05× 10⁻⁸.