A global analysis of π^0, K_S^0 and η fragmentation functions with BESIII data

In this research, we conduct a global QCD analysis of fragmentation functions (FFs) for neutral pions (π^0), neutral kaons (K_S^0), and eta mesons (η), utilizing world data of single inclusive hadron production in e^+e^- annihilation involving the most recent BESIII data with low collision energy, to test the operational region of QCD collinear factorization for single inclusive hadron production. We found that the QCD-based analysis at next-to-next-to leading order in perturbative QCD with parameterized higher-twist effects can explain both existing high-energy world data and the BESIII new measurements, while the latter cannot be explained with existing FFs extracted with high-energy data. To investigate the higher-twist contributions to this discrepancy, a direct functional approach is employed, providing testing framework for characterizing the experimental results over a wide range of energy scales, from low to high, thus extending the classical theoretical models to the BESIII domain.