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Published January 29, 2016 | Published
Journal Article Open

Observation of B → D^(*)π^+π^−ℓ^−ν Decays in e^+e^− Collisions at the Υ(4S) Resonance


We report on measurements of the decays of B mesons into the semileptonic final states B → D^(*)π^+π^−ℓ−ν, where D(*) represents a D or D∗ meson and ℓ^− is an electron or a muon. These measurements are based on 471×10^6 BB pairs recorded with the BABAR detector at the SLAC asymmetric B factory PEP-II. We determine the branching fraction ratios R^(*)_(π+π−)=B(B → D^(*)π^+π^−ℓ^−ν)/B(B → D^(*)ℓ^−ν) using events in which the second B meson is fully reconstructed. We find R_(π+π−)=0.067±0.010±0.008 and R^∗_(π+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^(*)ππℓ^−ν decays, where π denotes either a π^± and π^0 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.

Additional Information

© 2016 American Physical Society. Received 31 July 2015. Received 31 July 2015; published 26 January 2016. We are grateful for the excellent luminosity and machine conditions provided by our PEP-II colleagues, and for the substantial dedicated effort from the computing organizations that support BABAR. The collaborating institutions wish to thank SLAC for its support and kind hospitality. This work is supported by the DOE and the NSF (U.S.), NSERC (Canada), CEA and CNRS-IN2P3 (France), BMBF and DFG (Germany), INFN (Italy), FOM (Netherlands), NFR (Norway), MES (Russia), MINECO (Spain), STFC (United Kingdom), and BSF (U.S.-Israel). Individuals have received support from the Marie Curie EIF (European Union) and the A. P. Sloan Foundation (U.S.).

Attached Files

Published - PhysRevLett.116.041801.pdf


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