Abstract
The first observation of the suppressed semileptonic decay is reported. Using a data sample recorded in collisions in 2012 with the LHCb detector, corresponding to an integrated luminosity of , the branching fraction is measured to be , where the first uncertainty is statistical and the second one represents the combined systematic uncertainties. The decay , where is reconstructed in the final state , is used as a normalization channel to minimize the experimental systematic uncertainty. Theoretical calculations on the form factors of the and transitions are employed to determine the ratio of the Cabibbo-Kobayashi-Maskawa matrix elements at low and high momentum transfer.
- Received 9 December 2020
- Accepted 21 January 2021
DOI:https://doi.org/10.1103/PhysRevLett.126.081804
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