Abstract

Lifetimes of heavy hadrons are determined experimentally very precisely by now. On the theoretical side, the total decay width, namely the inverse of the lifetime, can be systematically computed in the framework of the heavy quark expansion (HQE) in terms of a series expansion in inverse powers of the heavy quark mass mQ. The applicability of the HQE strongly relies on the assumption that mQ is much larger than the typical hadronic scale, and in order to obtain precise theoretical predictions it is crucial to have good control on higher power corrections. In this talk, I will discuss the computation of the Darwin operator contribution, which corresponds to corrections of order mQ^{-3} in the HQE and review the current theoretical status for quantities like B and D mesons lifetime and mixing. Finally, by comparing precise measurements with the corresponding HQE predictions, it is possible to constrain the parameter space for new physics models that might e.g. explain the B anomalies.