B-meson mixing and lifetimes

Bd and Bs meson systems play a fundamental role to test and improve our understanding of Standard Model flavor dynamics. The mixing parameters Δmd,s represent important constraints in the unitarity triangle analysis. Their theoretical estimates require non-perturbative calculations of B-meson decay constants and B-parameters; accurate results, recently obtained from the lattice, are reviewed. Other phenomenologically interesting quantities are the beauty hadron lifetime ratios and, the width differences and CP-violation parameters in Bd and Bs systems. We discuss their theoretical predictions which, in the last four years, have been improved thanks to accurate lattice calculations and next-to-leading order perturbative computations.