CPasymmetry and branching ratio ofB→ππ

Abstract

We investigate the branching ratios and $CP$ asymmetries of the $B\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}$ processes measured in $B$ factory experiments. Fits to the experimental data of this process indicate a large ratio of color-suppressed ($C$) to color-allowed ($T$) tree contributions. We investigate whether the large $C/T$ can be explained within the QCD-based model computation with i) a large effect from the end point singularity or with ii) large final-state-interaction phase between two different isospin amplitudes. We show that the current experimental data do not exclude either possibility, but we may be able to distinguish these two effects in future measurements of direct $CP$ asymmetry of ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$.