Next-to-leading order QCD corrections to fully charm tetraquark radiative decays

We present the first complete next-to-leading-order (NLO) QCD calculation of the fully charm tetraquark radiative decays T4c(0⁺⁺,2⁺⁺)→γJ/ψ and T4c(1⁺⁻)→γηc at leading order in the relative velocity. The NLO widths are $2.3$--$3.1$ times the leading-order (LO) widths for the long-distance matrix element (LDME) inputs considered here, with mc=1.5 GeV and μR=2mc. In the scalar channel, the NLO corrections change the relative contributions of the two color-spin components and their interference. For the tensor channel, the longitudinal fraction fL of the daughter $J/ψ$ changes from $0.11$ at LO to $0.18$ at strictly expanded NLO, with sensitivity to higher-order corrections. These NLO results provide valuable theoretical input for searches for states predicted below their respective lowest dicharmonium thresholds and for probing the spin and short-distance structure of observed tetraquark candidates.