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 εand experimentally measured value of εis determined and used to obtain the value of \tilde εwith high precision. Present day knowledge of CKM matrix elements (including B-factory data), allows us to obtain from the Standard Model expression for \tilde εthe 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.
hep-ph↗