Complete Next-to-Next-to-Leading-Order QCD Correction to $J/\psi \to 3\gamma$ Decay

by Jianxiong Wang (IHEP, Chinese Academy of Sciences, Beijing, China)

Monday 6 Jul 2026, 10:15 → 11:15 Europe/Berlin

Nußallee 14-16/0.023 (HISKP) - Lecture Hall (HISKP)

We address the long-standing problem of negative decay and production rates in perturbative QCD for exclusive processes by proposing amplitude-level NRQCD factorization as a systematic prescription. Building on this, we present the first complete next-to-next-to-leading-order (NNLO) QCD correction to the decay J/ψ→3​γ. The resulting partial width, Γ​(J/ψ→3​γ)=0.96−0.13+4.32 eV, combines this NNLO contribution with the known up to 𝒪​(αs​v2) relativistic correction and shows markedly improved agreement with the high-precision BESIII measurement. In the same way, Γ​(Υ→3​γ)=0.0086−0.0006+0.0028 eV is obtained. The dominant theoretical uncertainty originates from the renormalization scale variation, underscoring the challenge of perturbative convergence at this order and the necessity for future higher-order calculations.