Abstract
The process $H \to J/\psi + \gamma$, where $H$ is the Higgs particle, provides a way to probe the size and the sign of the Higgs-charm coupling. In order to improve the theoretical control of the decay rate, we compute order $v^4$ corrections to the decay rate based on the nonrelativistic QCD factorization formalism. The perturbative calculation is carried out by using automated computer codes. We also resum logarithms of the ratio of the masses of the Higgs boson and the $J/\psi$ to all orders in the strong coupling constant $\alpha_s$ to next-to-leading logarithmic accuracy. In our numerical result for the decay rate, we improve the theoretical uncertainty, while our central value is in agreement with previous studies within errors. We also present numerical results for $H \to \Upsilon(nS) + \gamma$ for $n=1,2$, and 3, which turn out to be extremely sensitive to the Higgs bottom coupling.
Highlights
The investigation of the Higgs sector of the Standard Model is one of the most important areas of particle physics today
In order to improve the theoretical control of the decay rate, we compute order v4 corrections to the decay rate based on the nonrelativistic QCD factorization formalism
In Refs. [5,7,8], the large logarithms of m2H=m2V that appear in higher order corrections in αs, where mH is the Higgs mass and mV is the mass of the quarkonium V, have been resummed to all orders in αs by combining the nonrelativistic QCD (NRQCD) and the light-cone formalisms [11,12,13]
Summary
The investigation of the Higgs sector of the Standard Model is one of the most important areas of particle physics today. We improve the accuracy of the Standard Model prediction of the decay rates ΓðH → V þ γÞ for V 1⁄4 J=ψ or ΥðnSÞ for n 1⁄4 1, 2, and 3 by computing the order-v4 correction to the decay rate in the NRQCD factorization formalism. We do not consider the ψð2SÞ meson, because, to date, there are no available estimates of the relevant NRQCD matrix elements accounting for open-flavor threshold effects and nonrelativistic corrections in a complete and model-independent way These effects may be important for this state, as it is just 43 MeV below the DDthreshold. Higgs boson decays into a heavy quark Q and a heavy antiquark Qthrough the Yukawa interaction, and the QQpair forms a quarkonium after emitting a photon We compute this amplitude to order-v4 accuracy.
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