Probing new physics in B → πK decays

Abstract

Over the last two decades the B → πK decays have received a lot of attention. They are particularly interesting since the main contribution to these decays comes from QCD penguin topologies. Furthermore, electroweak penguin amplitudes give a contribution comparable to the tree topologies. In the past, a discrepancy was found in the correlation between the CP asymmetries of B0d → π0KS. We give an up-to-date picture of this situation and consider new constraints, finding that the effect has become larger. An attractive explanation is offered by a modified electroweak penguin sector. We employ an isospin relation between the amplitudes of the B → πK decays to determine the relevant parameters, making only minimal use of the SU(3) flavour symmetry. Another essential constraint is provided by the mixing-induced CP asymmetry of B0d → π0KS. The application of our strategy at the next generation of B-physics experiments may establish New Physics and reveal new sources of CP violation in the electroweak penguin sector.