Quantum Anomalies in Deeply Virtual Meson Production

In recent years, interesting connections have been identified between quantum anomalies—quantum effects that signal deviations from classical symmetries—and Generalized Parton Distributions (GPDs), which are multidimensional functions describing the internal structure of the nucleon. This connection was first established in deeply virtual Compton scattering, a process sensitive to GPDs. These anomalies, typically manifested as infrared poles, are tied to fundamental aspects of Quantum Chromodynamics (QCD) such as chiral symmetry breaking and mass generation. We now perform one-loop calculations in deeply virtual meson production, another process central to the study of GPDs at the future Electron–Ion Collider in the United States, and find that anomaly poles also appear here, thereby confirming the robustness of GPDs and their connection to anomaly poles. Our analysis shows that the anomaly pole arises within triangle-, box-, and pentagon-type Feynman diagram topologies, thereby clarifying how quantum anomalies manifest in QCD through measurable observables.