The first observation of the semileptonic b-baryon decay Λb0 → Λc+ τ− anti-ν_τ, with a significance of 6.1 σ, is reported using a data sample corresponding to 3 fb^−1 of integrated luminosity, collected by the LHCb experiment at center-of-mass energies of 7 and 8 TeV at the LHC. The τ− lepton is reconstructed in the hadronic decay to three charged pions. The ratio K = B(Λb0 → Λc+ τ− anti-ν_τ) / B(Λb0 → Λc+ π− π+ π−) is measured to be 2.46 ± 0.27 ± 0.40, where the first uncertainty is statistical and the second systematic. The branching fraction B(Λb0 → Λc+ τ− anti-ν_τ) = (1.50 ± 0.16 ± 0.25 ± 0.23)% is obtained, where the third uncertainty is from the external branching fraction of the normalization channel Λb0 → Λc+ π− π+ π−. The ratio of semileptonic branching fractions R(Λc+) ≡ B(Λb0 → Λc+ τ− anti-ν_τ) / B(Λb0 → Λc+ μ− anti-ν_μ) is derived to be 0.242 ± 0.026 ± 0.040 ± 0.059, where the external branching fraction uncertainty from the channel Λb0 → Λc+ μ− anti-ν_μ contributes to the last term. This result is in agreement with the standard model prediction.

Observation of the Decay Λb0 → Λc+ τ-(ν)over-barτ

Calabrese, R.;Capriotti, L.;Couturier, B.;Fiorini, M.;Franzoso, E.;Giugliano, C.;Guarise, M.;Kotriakhova, S.;Luppi, E.;Okamura, S.;Pappalardo, L. L.;Passalacqua, B.;Tomassetti, L.;
2022

Abstract

The first observation of the semileptonic b-baryon decay Λb0 → Λc+ τ− anti-ν_τ, with a significance of 6.1 σ, is reported using a data sample corresponding to 3 fb^−1 of integrated luminosity, collected by the LHCb experiment at center-of-mass energies of 7 and 8 TeV at the LHC. The τ− lepton is reconstructed in the hadronic decay to three charged pions. The ratio K = B(Λb0 → Λc+ τ− anti-ν_τ) / B(Λb0 → Λc+ π− π+ π−) is measured to be 2.46 ± 0.27 ± 0.40, where the first uncertainty is statistical and the second systematic. The branching fraction B(Λb0 → Λc+ τ− anti-ν_τ) = (1.50 ± 0.16 ± 0.25 ± 0.23)% is obtained, where the third uncertainty is from the external branching fraction of the normalization channel Λb0 → Λc+ π− π+ π−. The ratio of semileptonic branching fractions R(Λc+) ≡ B(Λb0 → Λc+ τ− anti-ν_τ) / B(Λb0 → Λc+ μ− anti-ν_μ) is derived to be 0.242 ± 0.026 ± 0.040 ± 0.059, where the external branching fraction uncertainty from the channel Λb0 → Λc+ μ− anti-ν_μ contributes to the last term. This result is in agreement with the standard model prediction.
2022
Aaij, R.; Abdelmotteleb, A. S. W.; Abellán Beteta, C.; Abudinén, F.; Ackernley, T.; Adeva, B.; Adinolfi, M.; Afsharnia, H.; Agapopoulou, C.; Aidala, C...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2500491
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