Model-independent bounds on new physics effects in non-leptonic tree-level decays of B-mesons

Abstract

We present a considerably improved analysis of model-independent bounds on new physics effects in non-leptonic tree-level decays of B-mesons. Our main finding is that contributions of about ±0.1 to the Wilson coefficient of the colour-singlet operator Q2 of the effective weak Hamiltonian and contributions in the range of ±0.5 (both for real and imaginary part) to Q1 can currently not be excluded at the 90% C.L. Effects of such a size can modify the direct experimental extraction of the CKM angle γ by up to 10° and they could lead to an enhancement of the decay rate difference ∆Γd of up to a factor of 5 over its SM value — a size that could explain the D0 dimuon asymmetry. Future more precise measurements of the semi-leptonic asymmetries aslq and the lifetime ratio τ (Bs)/τ (Bd) will allow to shrink the bounds on tree-level new physics effects considerably. Due to significant improvements in the precision of the non-perturbative input we update all SM predictions for the mixing obervables in the course of this analysis, obtaining: ∆Ms = (18.77 ± 0.86) ps−1, ∆Md = (0.543 ± 0.029) ps−1, ∆Γs = (9.1 ± 1.3) · 10−2 ps−1, ∆Γd = (2.6 ± 0.4) · 10−3 ps−1, aslq = (2.06 ± 0.18) · 10−5 and asld = (−4.73 ± 0.42) · 10−4.