QCD-based estimate of direct $CP$ asymmetry in charm decays

TL;DR

This paper estimates the direct CP asymmetry in charm decays using QCD light-cone sum rules, providing an upper limit that is much smaller than recent experimental measurements.

Contribution

It introduces a QCD-based theoretical calculation of CP asymmetry differences in charm decays, offering a new upper limit that challenges recent experimental findings.

Findings

Upper limit for CP asymmetry difference: < 0.020%

Theoretical estimate is significantly smaller than LHCb measurements

Supports the need for further theoretical and experimental investigation

Abstract

I discuss the calculation of the direct CP-asymmetry in $D\to \pi^+\pi^-$ and $D\to K^+K^- $ decays with the method of QCD light-cone sum rules. The main result is the upper limit for the difference of the two asymmetries $\left|\Delta a_{CP}^{dir}\right| < 0.020\pm 0.003\%$ which is significantly smaller than the recent measurement of this quantity by the LHCb collaboration