Indirect Cp Violation in the B - System

We show that, contrary to the flavour mixing amplitude q/p, both Re(ε) and Im(ε) are observable quantities, where ε is the phase-convention-independent CP mixing. We consider semileptonic B d decays from a CP tag and build appropriate time-dependent asymmetries to separate out Re(ε) and Im(ε). " Indirect " CP violation would have in Im(ε)/(1 + |ε| 2) its most prominent manifestation in the B-system, with expected values in the standard model ranging from −0.37 to −0.18. This quantity is controlled by a new observable ph ase: the relative one between the CP-violating and CP-conserving parts of the effective hamiltonian. For time-integrated rates we point out a ∆Γ → ΣΓ transmutation which operates in the perturbative CP mixing.