Abstract
The first observation of the semileptonic -baryon decay , with a significance of , is reported using a data sample corresponding to of integrated luminosity, collected by the LHCb experiment at center-of-mass energies of 7 and 8 TeV at the LHC. The lepton is reconstructed in the hadronic decay to three charged pions. The ratio is measured to be , where the first uncertainty is statistical and the second systematic. The branching fraction is obtained, where the third uncertainty is from the external branching fraction of the normalization channel . The ratio of semileptonic branching fractions is derived to be , where the external branching fraction uncertainty from the channel contributes to the last term. This result is in agreement with the standard model prediction.
- Received 11 January 2022
- Accepted 29 March 2022
DOI:https://doi.org/10.1103/PhysRevLett.128.191803
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