The value of B_K from the experimental data on CP-violation in K-mesons and up-to-date values of CKM matrix parameters

The difference between induced by box diagram quantity \tilde \epsilon and experimentally measured value of \epsilon is determined and used to obtain the value of \tilde \epsilon with high precision. Present day knowledge of CKM matrix elements (including B-factory data), allows us to obtain from the Standard Model expression for \tilde \epsilon the value of parameter B_K: B_K = 0.89 \pm0.16. It turns out to be very close to the result of vacuum insertion, B_K = 1.