D-Dbar mixings from nonlocal condensate contributions

A significant discrepancy, spanning multiple orders of magnitude, exists between the leading order contribution to the 𝐷𝐷 mixing parameters and experimental values. This is largely due to the Glashow–Iliopoulos–Maiani (GIM) mechanism, which results in substantial suppression of the theoretical predictions. To bridge this gap, various efforts have been made to account for higher-order terms and nonperturbative effects, which, although suppressed in the operator product expansion (OPE), could potentially lead to a larger contribution by weakening the GIM cancellation through flavour SU(3) symmetry breaking. In this work, we compute the long- distance contributions of nonlocal QCD condensates within different models and, for the first time, determine the impact of the mixed condensate. Although our results still fall short of the experimental value, they represent an improvement over current theoretical estimates by an order of magnitude.