Nonperturbative Dynamics in D-meson Mixing

TL;DR

This paper explores nonperturbative QCD effects, including mixed condensates, to improve theoretical predictions of D-meson mixing parameters, addressing discrepancies with experimental data.

Contribution

It introduces the first analysis of mixed quark-gluon and four-quark condensates' effects on D-meson mixing, significantly enhancing theoretical estimates.

Findings

Predicted mixing parameters increase by two orders of magnitude.

Nonperturbative effects are crucial for accurate D-meson mixing predictions.

Theoretical estimates still below experimental values, guiding future research.

Abstract

Theoretical predictions for the $D^0\overline{D^0}$ mixing parameters fall significantly short of experimental measurements, with discrepancies spanning several orders of magnitude. This gap is mainly due to the Glashow-Iliopoulos-Maiani (GIM) mechanism, which suppresses leading-order contributions by high powers of $m_s/m_c$. However, higher-order corrections and nonperturbative effects could reduce this suppression, especially through flavor $SU(3)_F$ symmetry breaking. In this work, we investigate the long-distance contributions from QCD condensates, including, for the first time, the effects of mixed quark-gluon and four-quark condensates. Our results show an increase in the predicted values of $D^0\overline{D^0}$ mixing parameters by two orders of magnitude compared to perturbative NLO result, providing valuable insights into nonperturbative QCD dynamics. Although the theoretical estimates still fall below experimental values, this study represents an important step toward narrowing the gap between theory and observation, highlighting the significance of higher-order $1/m_c$ QCD effects in understanding $D^0\overline{D^0}$ mixing.