Extracting and using photon polarization information in radiative B decays

Abstract

We discuss the uses of conversion electron pairs for extracting photon polarization information in weak radiative B decays. Both cases of leptons produced through a virtual and real photon are considered. Measurements of the angular correlation between the $(K\pi)$ and $(e^+e^-)$ decay planes in $B\to K^*(\to K\pi)\gamma^{(*)}(\to e^+e^-)$ decays can be used to determine the helicity amplitudes in the radiative $B\to K^*\gamma$ decay. A large right-handed helicity amplitude in $\bar B$ decays is a signal of new physics. The time-dependent CP asymmetry in the $B^0$ decay angular correlation is shown to measure $\sin 2\beta$ and $\cos 2\beta$ with little hadronic uncertainty.