Abstract
The first observation of the decay is reported, with a significance of more than seven standard deviations, from an analysis of collision data corresponding to an integrated luminosity of , collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. The branching fraction is measured relative to that of the topologically similar decay and is found to be , where the first uncertainty is statistical, the second systematic, and the third from the branching fraction of the decay. The fraction of longitudinal polarization in this decay is measured to be . The most precise determination of the branching fraction for the decay is also obtained, . An upper limit, at 90% (95%) confidence level is set. A constraint on the mixing angle is set at (5.5°) at 90% (95%) confidence level.
- Received 6 July 2018
DOI:https://doi.org/10.1103/PhysRevD.98.071103
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© 2018 CERN, for the LHCb Collaboration