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 $\pm 0.1$ to the Wilson coefficient of the colour-singlet operator $Q_2$ of the effective weak Hamiltonian and contributions in the range of $\pm 0.5$ (both for real and imaginary part) to $Q_1$ 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 $\gamma$ by up to $10^{\circ }$ and they could lead to an enhancement of the decay rate difference $\Delta {\Gamma }_d$ 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 $a_{sl}^q$ and the lifetime ratio $\tau (B_s)/\tau (B_d)$ 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: $\Delta M_s=(18.77\pm 0.86)\text{mbox}{ps}^{-1}$, $\Delta M_d=(0.543\pm 0.029)\text{mbox}{ps}^{-1}$, $\Delta {\Gamma }_s=(9.1\pm 1.3)\cdot 10^{-2}\text{mbox}{ps}^{-1}$, $\Delta {\Gamma }_d=(2.6\pm 0.4)\cdot 10^{-3}\text{mbox}{ps}^{-1}$, $a_{sl}^s=(2.06\pm 0.18)\cdot 10^{-5}$ and $a_{sl}^d=(-4.73\pm 0.42)\cdot 10^{-4}$.

Comments: 81 pages, 26 figures. Version published in JHEP