Bs-antiBs mixing and lifetimes

Abstract

We review the status of mixing of neutral B-mesons, including a discussion of the current precision of Standard Model (SM) predictions as well as the space that is left for effects of new physics. In that respect we present several observables, which are particularly sensitive to the remaining new physics (NP) parameter space. B-mixing can also be used to test the fundaments of quantum mechanics, here we suggest a new measurement of the ratio of like-sign dilepton events to opposite-sign dilepton events. Finally we summarise briefly the status of lifetimes of heavy hadrons. The corresponding theory predictions rely on the same tool -the Heavy Quark Expansion (HQE) -as some of the mixing quantities. New experimental data has recently proven the validity of the HQE to a high accuracy. However, the theoretical precision of lifetime predictions is strongly limited by a lack of non-perturbative evaluations of matrix elements of dimension-six operators.The 15th International Conference on B-Physics at Frontier Machines at the University of Edinburgh, 14 -18 July, 2014 University of Edinburgh, UK * Speaker.

Towards New Physics Through Precision Measurements in B$^0_S$ and $\tau$ Decays

“…The mass difference of the two mass eigenstates ∆M s = M H − M L is given by the offshell intermediate states of the box diagrams in figure 2.1 [42], thus it is sensitive to heavy internal particles contributions, such as the top quark or the W-boson in the SM, or BSM particles that may contribute. The decay rate difference ∆Γ s = Γ L − Γ H is given by on-shell intermediate states, then it is sensitive to light internal particles.…”