New Physics and Evidence for a Complex CKM

Abstract

We carefully analyse the present experimental evidence for a complex CKM matrix, even allowing for New Physics contributions to ${ϵ}_K$, $a_{J/\Psi K_S}$, $\Delta M_{B_d}$, $\Delta M_{B_s}$, and the $\Delta I=1/2$ piece of $B\to \rho \rho$ and $B\to \rho \pi$. We emphasize the crucial rôle played by the angle $\gamma$ in both providing irrefutable evidence for a complex CKM matrix and placing constraints on the size of NP contributions. It is shown that even if one allows for New Physics a real CKM matrix is excluded at a 99.92% C.L., and the probability for the phase $\gamma$ to be in the interval $[-170^{\circ };-10^{\circ }]\cup [10^{\circ };170^{\circ }]$ is 99.7%.

Comments: 24 pages, 15 figures. Revised version, analyses extended to more general New Physics; C.L. of exclusion of a real CKM matrix included