Exploring CP Violation with B_d -> D K_s Decays

Abstract

We (re)examine CP violation in the decays B_d -> D K_s, where D represents D^0, D(bar), or one of their excited states. The quantity $\sin^2(2\beta + \gamma)$ can be extracted from the time-dependent rates for $B_d(t) -> {\bar D}^{**0} K_s$ and $B_d(t) -> D^{**0} K_s$, where the $D^{**0}$ decays to $D^{(*)+}\pi^-$. If one considers a non-CP-eigenstate hadronic final state to which both D(bar) and D^0 can decay (e.g. $K^+\pi^-$), then one can obtain two of the angles of the unitarity triangle from measurements of the time-dependent rates for $B_d(t) -> (K^+\pi^-)_{D K_s}$ and $B_d(t) -> (K^-\pi^+)_{D K_s}$. There are no penguin contributions to these decays, so all measurements are theoretically clean.