Measurement of the B- -> D0 l- nubar_l Branching Fraction in 62.8/fb of Belle II data

We report a measurement of the branching fraction of the semileptonic decay B- -> D0 l- nubar_l (and its charge conjugate) using 62.8/fb of Upsilon(4S) -> B Bbar data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy e+ e- collider. The neutral charm meson is searched for in the decay mode D0 -> K- pi+ and combined with a properly charged identified lepton (electron or muon) to reconstruct this decay. No reconstruction of the second B meson in the Upsilon(4S) event is performed. We obtain Br( B- -> D0 l- nubar_l ) = (2.29 +/- 0.05(stat) +/- 0.08(syst))%, in agreement with the world average of this decay. We also determine the ratio of the electron to muon branching fractions to be R(e/mu) = 1.04 +/- 0.05(stat) +/- 0.03(syst) and observe no deviation from lepton universality.