Possible Indications of New Physics in Bd-mixing and in sin(2 beta) Determinations

Abstract

Using the hadronic matrix elements from the lattice, B_K and xi_s, involving only the 4-quark operators for Delta flavor (F) = 2 Hamiltonian relevant for K, B_d and B_s mixing, along with V_cb, we deduce a non-trivial constraint on the SM, sin (2 beta) = 0.87+-0.09. This deviates from direct experimental measurements via the tree process, b -> c c s as well as the one via the penguin-loop b -> s decays by around 2.1 and 2.7 sigma respectively. If these deviations are confirmed they would imply the presence of new physics rather pervasively in both B_d mixing (i.e. very likely in b -> d) as well as in b -> s transitions requiring a beyond the SM CP-odd phase. Consequently, improvements in the relevant lattice calculations should be given a high priority.

4 pages, 2 eps figures. References added. A corrected expression for epsilon_K, following the paper from Buras and Guadagnoli (arXiv:0805.3887), is used and small changes in the numerics due to the new formula are propagated