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

Understand

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.