CP Violation in B Decays within QCD Factorization

Abstract

We analyze the extraction of weak phases from CP violation in $B\to {\pi }^{+}{\pi }^{-}$ decays. By combining the information on mixing induced CP violation in $B\to {\pi }^{+}{\pi }^{-}$, namely $S_{\pi \pi }$, with the precision observable $\sin 2\beta$ obtained from the ``gold-plated''mode $B\to \psi K_S$, we propose the determination of the unitarity triangle. We also discuss alternative ways to analyze $S_{\pi \pi }$ which can be useful if new physics affects $B_d$--${\bar{B}}_d$ mixing. Predictions and uncertainties for $r$ and $\varphi$ in QCD factorization are examined in detail. It is pointed out that a simultaneous expansion in $1/m_b$ and $1/N_C$ leads to interesting simplifications. At first order infrared divergences are absent, while the most important effects are retained. Independent experimental tests of the factorization framework are briefly discussed.

Comments: 3 pages; 2 figures; To appear in the proceedings of International Europhysics Conference on High-Energy Physics (HEP 2003), Aachen, Germany, 17-23 Jul 2003