Lifetime differences and CP violation parameters of neutral B mesons at the next-to-leading order in QCD

We compute the next-to-leading order QCD corrections to the off-diagonal elements of the decay-width matrix Γ entering the neutral B-meson oscillations. From this calculation the width differences ΔΓ and the CP violation parameters (q/p) of B d and B s mesons are estimated, including the complete O (αs) QCD corrections and the 1/m b contributions. For the width differenceΔΓ s we agree with previous results. By using the lattice determinations of the relevant hadronic matrix elements we obtain the theoretical predictions ΔΓ d /Γ d = (2.42±0.59) x 10-3 and ΔΓ s /Γ s (7.4±2.4) x 10-2 . For the CP violation parameters, we find vertical bar(q/p) d vertical bar-1 = (2.96±0.67) x 10-4 and vertical bar(q/p) s vertical bar-1 = -(1.28±0.27) x 10-5 . These predictions are compatible with the experimental measurements which, however, suffer at present from large uncertainties. (author)