$D^0\overline{D^0}$ mixing from nonlocal condensate contributions

TL;DR

This paper investigates long-distance contributions to $D^0ar{D}^0$ mixing from nonlocal QCD condensates, aiming to reconcile theoretical predictions with experimental data by including mixed condensate effects.

Contribution

It introduces the first calculation of the impact of mixed condensates on $D^0ar{D}^0$ mixing, improving theoretical estimates significantly.

Findings

Results are an order of magnitude closer to experimental values.

Mixed condensate contributions enhance the theoretical estimates.

The work highlights the importance of nonlocal condensates in meson mixing.

Abstract

A significant discrepancy, spanning multiple orders of magnitude, exists between the leading order contribution to the $D^0\overline{D^0}$ 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.