Branching fraction measurement of (B)over-bar0→ D(*)+π- and B-→ D(*)0π- and isospin analysis of (B)over-bar → D(*)π decays

Using 65 X 10(6) Y (4S) -> BB events collected with the BABAR detector at the PEP-II e(+) e(-) storage ring at the Stanford Linear Accelerator Center, we measure the color-favored branching fractions B(B-0 -> D+ pi(-)) = (2.55 +/- 0.05 +/- 0.16) X 10(-3), B(B-0 -> D*(+) pi(-)) = (2.79 +/- 0.08 +/- 0.17) X 10(-3), B(B- -> D-0 pi(-)) = (4.90 +/- 0.07 +/- 0.22) X 10(-3) and B(B- -> D*(0)pi(-)) = (5.52 +/- 0.17 +/- 0.42) X 10(-3), where the first error is statistical and the second is systematic. With these results and the current world average for the branching fraction for the color-suppressed decay B-0 -> D-(*()0)pi(0), the cosines of the strong phase difference delta between the I =1/2 and I = 3/2 isospin amplitudes are determined to be cos delta = 0.872(-0.007 - 0.029)(+0.008+0.031) for the B -> D pi process and cos delta = 0.924(-0.017 - 0.054)(+ 0.019 + 0.063) for the B -> D*pi process. Under the isospin symmetry, the results for cos delta suggest the presence of final-state interactions in the D pi system.