Rescattering effects in charmless decays

Abstract

Final-state interaction effects in charmless B u,d,s → P P decays are studied. We investigate the B 0 → π + π − , π 0 π 0 rates and the Kπ direct CP violations, which lead to the so-called Kπ puzzle in CP violation. Our main results are as follows: (i) Results are in agreement with data in the presence of FSI. (ii) For B decays, the π + π − and π 0 π 0 rates are suppressed and enhanced respectively by FSI. (iii) The FSI has a large impact on direct CP asymmetries (A) of many modes. (iv) The deviation(∆A) between A(B 0 → K − π + ) and A(B − → K − π 0 ) can be understood in the FSI approach. (v) Sizable and complex color-suppressed tree amplitudes, which are crucial for the large π 0 π 0 rate and ∆A, are generated through exchange rescattering. The correlation of the ratio B(π 0 π 0 )/B(π + π − ) and ∆A is studied. (vi) The B − → π − π 0 direct CP violation is very small and is not affected by FSI. (vii) Several Bs decay rates are enhanced. In particular, the η ′ η ′ branching ratio is enhanced to the level of 1.0 × 10 −4 . (viii) Time-dependent CP asymmetries S in B d,s decays are studied. The ∆S(B 0 → K S η ′ ) is very small (≤ 1%). We found that the asymmetries |S| for B 0 s → ηη, ηη ′ and η ′ η ′ decays are all below 0.06. CP asymmetries in these modes will be useful to test the SM.

CP violation in the B system

“…1, the tree and penguin diagrams involved differ only by the spectator quark, and therefore if only these diagrams contribute then similar asymmetries, and ∆A CP (B → Kπ) ≈ 0, would be expected. Additional subleading amplitudes which contribute only to the B + → K + π 0 decay and QCD corrections can, however, potentially explain the effect [325][326][327][328].…”