title: Difference in B+ and B0 direct CP asymmetry as an effect of a fourth generation.
abstract: Direct CP violation in B0 --> K+ pi- decay has emerged at the -10% level, but the asymmetry in B+ --> K+ pi0 mode is consistent with zero. This difference points towards possible new physics in the electroweak penguin operator. We point out that a sequential fourth generation, with sizable V(t' s)* V(t' b) and near maximal phase, could be a natural cause. We use the perturbative QCD factorization approach for B --> Kpi amplitudes. While the B0 --> K+ pi- mode is insensitive to t', we critically compare t' effects on direct CP violation in B+ --> K+ pi0 with b --> sl+ l- and B(s) mixing. If the K+ pi0 - K+ pi- asymmetry difference persists, we predict sin2phi(Bs) to be negative.
authors.affiliation: Department of Physics, National Taiwan University, Taipei, Taiwan 106, Republic of China.
authors.forename: Wei-Shu
authors.initials: WS
authors.lastname: Hou
authors.forename: Makiko
authors.initials: M
authors.lastname: Nagashima
authors.forename: Andrea
authors.initials: A
authors.lastname: Soddu