CP Violation in B Decays within QCD Factorization
Abstract
We analyze the extraction of weak phases from CP violation in
B→
π
+
π
−
decays. By combining the information on mixing induced CP violation in
B→
π
+
π
−
, namely
S
ππ
, with the precision observable
sin2β
obtained from the ``gold-plated''mode
B→ψ
K
S
, we propose the determination of the unitarity triangle. We also discuss alternative ways to analyze
S
ππ
which can be useful if new physics affects
B
d
--
B
¯
d
mixing. Predictions and uncertainties for
r
and
ϕ
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.