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.