Penguin Pollution in Β and Β S

The mixing-induced CP asymmetries in Bd → J/ψKS and Bs → J/ψφ are essential to detect or constrain new physics in the Bd−Bd and Bs−Bs mixing amplitudes, respectively. To this end one must control the penguin contributions to the decay amplitudes, which affect the extraction of fundamental CP phases from the measured CP asymmetries. Although the “penguin pollution” is doubly Cabibbo-suppressed, it could compete in size with current experimental errors. In this talk I present a calculation of the penguin contributions treating QCD effects with soft-collinear factorisation and compare method and results with the alternative approach employing flavourSU(3) symmetry. As a novel feature, I present results for the penguin pollution in b→ ccd modes.