Measurement of branching fractions and CP-violating charge asymmetries for B-meson decays to D(*)¯¯¯D(*), and implications for the Cabibbo-Kobayashi-Maskawa angle γ

Abstract

We present measurements of the branching fractions and charge asymmetries of B decays to all D ( * ) ¯¯¯ D ( * ) modes. Using 232 × 10 6 B ¯¯¯ B pairs recorded on the Υ ( 4 S ) resonance by the BABAR detector at the e + e − asymmetric B factory PEP-II at the Stanford Linear Accelerator Center, we measure the branching fractions B ( B 0 → D * + D * − ) = ( 8.1 ± 0.6 ± 1.0 ) × 10 − 4 , B ( B 0 → D * ± D ∓ ) = ( 5.7 ± 0.7 ± 0.7 ) × 10 − 4 , B ( B 0 → D + D − ) = ( 2.8 ± 0.4 ± 0.5 ) × 10 − 4 , B ( B + → D * + ¯¯¯ D * 0 ) = ( 8.1 ± 1.2 ± 1.2 ) × 10 − 4 , B ( B + → D * + ¯¯¯ D 0 ) = ( 3.6 ± 0.5 ± 0.4 ) × 10 − 4 , B ( B + → D + ¯¯¯ D * 0 ) = ( 6.3 ± 1.4 ± 1.0 ) × 10 − 4 , and B ( B + → D + ¯¯¯ D 0 ) = ( 3.8 ± 0.6 ± 0.5 ) × 10 − 4 , where in each case the first uncertainty is statistical and the second systematic. We also determine the limits B ( B 0 → D * 0 ¯¯¯ D * 0 ) < 0.9 × 10 − 4 , B ( B 0 → D * 0 ¯¯¯ D 0 ) < 2.9 × 10 − 4 , and B ( B 0 → D 0 ¯¯¯ D 0 ) < 0.6 × 10 − 4 , each at 90% confidence level. All decays above denote either member of a charge-conjugate pair. We also determine the C P -violating charge asymmetries A ( B 0 → D * ± D ∓ ) = 0.03 ± 0.10 ± 0.02 , A ( B + → D * + ¯¯¯ D * 0 ) = − 0.15 ± 0.11 ± 0.02 , A ( B + → D * + ¯¯¯ D 0 ) = − 0.06 ± 0.13 ± 0.02 , A ( B + → D + ¯¯¯ D * 0 ) = 0.13 ± 0.18 ± 0.04 , and A ( B + → D + ¯¯¯ D 0 ) = − 0.13 ± 0.14 ± 0.02 . Additionally, when we combine these results with information from time-dependent C P asymmetries in B 0 → D ( * ) + D ( * ) − decays and world-averaged branching fractions of B decays to D ( * ) s ¯¯¯ D ( * ) modes, we find the Cabibbo-Kobayashi-Maskawa phase γ is favored to lie in the range (0.07-2.77) radians (with a + 0 or + π radians ambiguity) at 68% confidence level.