We report on measurements of the decays of B¯ mesons into the semileptonic final states B¯→D(∗)π+π-ν¯, where D(∗) represents a D or D∗ meson and - is an electron or a muon. These measurements are based on 471×106 BB¯ pairs recorded with the BABAR detector at the SLAC asymmetric B factory PEP-II. We determine the branching fraction ratios Rπ+π-(∗)=B(B¯→D(∗)π+π-ν¯)/B(B¯→D(∗)-ν¯) using events in which the second B meson is fully reconstructed. We find Rπ+π-=0.067±0.010±0.008 and Rπ+π-∗=0.019±0.005±0.004, where the first uncertainty is statistical and the second is systematic. Based on these results and assuming isospin invariance, we estimate that B¯→D(∗)ππ-ν¯ decays, where π denotes either a π± and π0 meson, account for up to half the difference between the measured inclusive semileptonic branching fraction to charm hadrons and the corresponding sum of previously measured exclusive branching fractions.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)