Cyuan-Han Chang, Hao Chen, Xiaohui Liu, David Simmons–Duffin, Feng Yuan, Hua Xing Zhu
We study the QCD scaling behavior of the small-angle energy-energy correlator (EEC), focusing on the transition between its perturbative preconfinement and nonperturbative postconfinement regimes. Applying the light-ray operator product expansion (OPE), we develop a formalism that describes the scaling of the EEC with the input energy Q in the transition and the postconfinement region, where the latter quantum scaling is determined by the J=5 DGLAP anomalous dimension. A key result of our Letter is a novel connection between the light-ray OPE and the dihadron fragmentation function (DFF), where we show that the nonperturbative OPE coefficients correspond to moments of the DFF. This finding establishes a new paradigm for studying hadronization. Our theoretical predictions are validated against Monte Carlo simulations for both e^{+}e^{-} and pp collisions, showing excellent agreement. The potential role of the quantum scaling in the precision determination of α_{s} is also discussed.