Calculation of the K^0-\bar{K}^0 mixing parameter via the QCD sum rules at finite energies

Abstract

The QCD finite energy sum rules method is used to show that the parameter of the K^0-\bar{K}_0 mixing \hat{B} is mainly determined by the value of g m_s< \bar{d} G_{\mu\nu} \sigma_{\mu\nu} d > and the vacuum expectation values of four-quark operators. Assuming the hypothesis of vacuum dominance and/or unitarity symmetry to estimate latter, it is found that \hat{B}=1.2\pm 0.1. (The updated (March 2001) prediction reads \hat{B} = 1.0 +- 0.1 (for more details, see Comments after the main text).