1211.4539 (Wei Wang)

CP violation effects on the measurement of $γ$ from $B\to DK$    [PDF]

Wei Wang

We point out the "theoretically-clean" method to extract the CKM angle $\gamma$ from $B\to DK$ with $D$ decays into CP eigenstate $K^+K^-$ or $\pi^+\pi^-$ is not clean in fact. We study the impact caused by the direct CP violation in D meson decays and show that the extracted results for $\gamma$ can be shifted by ${\cal O}(A_{CP} / r_B^K)$, where $A_{CP}$ is the direct CP asymmetry in $D$ decays and $r_B^K$ is the ratio of the decay amplitudes of $B^-\to \bar D^0K^-$ and $B^-\to D^0K^-$. Using the recent data on CP asymmetry, we find the correction to physical observables in $B\to DK$ can reach 6%, which corresponds to the modification of $\gamma$ by roughly $5^\circ$. The future experimental measurements must include these effects. Further theoretical uncertainties can be reduced to less than $0.5^\circ$ depending on the size of the strong phase in $D$ decays.

View original: http://arxiv.org/abs/1211.4539