Observation of the decay Λb0 → Λc+ τ- ν̄τ

LHCb Collaboration

doi:10.1103/PhysRevLett.128.191803

Observation of the decay Λ_b⁰ → Λ_c⁺ τ^- ν̄_τ

LHCb Collaboration

Physics and Astronomy

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Abstract

The first observation of the semileptonic b-baryon decay Λ_b⁰→Λ_c⁺τ^-ν̄_τ, with a significance of 6.1σ, 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(Λ_b⁰→Λ_c⁺τ^-ν̄_τ)/B(Λ_b⁰→Λ_c⁺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(Λ_b⁰→Λ_c⁺τ^-ν̄_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 Λ_b⁰→Λ_c⁺π^-π⁺π^-. The ratio of semileptonic branching fractions R(Λ_c⁺)B(Λ_b⁰→Λ_c⁺τ^-ν̄_τ)/B(Λ_b⁰→Λ_c⁺μ^-ν̄_μ) is derived to be 0.242±0.026±0.040±0.059, where the external branching fraction uncertainty from the channel Λ_b⁰→Λ_c⁺μ^-ν̄_μ contributes to the last term. This result is in agreement with the standard model prediction.

Original language	English
Article number	191803
Number of pages	11
Journal	Physical Review Letters
Volume	128
Issue number	19
DOIs	https://doi.org/10.1103/PhysRevLett.128.191803
Publication status	Published - 13 May 2022

Bibliographical note

Funding Information:
We express our gratitude to our colleagues in the CERN accelerator departments for the excellent performance of the LHC. We thank the technical and administrative staff at the LHCb institutes. We acknowledge support from CERN and from the national agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); MOST and NSFC (China); CNRS/IN2P3 (France); BMBF, DFG and MPG (Germany); INFN (Italy); NWO (Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MSHE (Russia); MICINN (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and NSF (USA). We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland), and NERSC (USA). We are indebted to the communities behind the multiple open-source software packages on which we depend. Individual groups or members have received support from ARC and ARDC (Australia); AvH Foundation (Germany); EPLANET, Marie Skłodowska-Curie Actions and ERC (European Union); A*MIDEX, ANR, IPhU, and Labex P2IO, and Région Auvergne-Rhóne-Alpes (France); Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP, Fundamental Research Funds for the Central Universities, and Sci. & Tech. Program of Guangzhou (China); RFBR, RSF, and Yandex LLC (Russia); GVA, XuntaGal, and GENCAT (Spain); the Leverhulme Trust, the Royal Society, and UKRI (United Kingdom).

Publisher Copyright:
© 2022 CERN.

ASJC Scopus subject areas

General Physics and Astronomy

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Cite this

@article{e9890f0885094327a7357148bbd8e511,

title = "Observation of the decay Λb0 → Λc+ τ- {\=ν}τ",

abstract = "The first observation of the semileptonic b-baryon decay Λb0→Λc+τ-{\=ν}τ, with a significance of 6.1σ, 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-{\=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-{\=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-{\=ν}τ)/B(Λb0→Λc+μ-{\=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-{\=ν}μ contributes to the last term. This result is in agreement with the standard model prediction.",

author = "{LHCb Collaboration} and R. Aaij and Abdelmotteleb, {A. S.W.} and Beteta, {C. Abell{\'a}n} and F. Abudin{\'e}n and T. Ackernley and B. Adeva and M. Adinolfi and H. Afsharnia and C. Agapopoulou and Aidala, {C. A.} and S. Aiola and Z. Ajaltouni and S. Akar and J. Albrecht and F. Alessio and M. Alexander and Albero, {A. Alfonso} and Z. Aliouche and G. Alkhazov and Cartelle, {P. Alvarez} and S. Amato and Amey, {J. L.} and Y. Amhis and L. An and L. Anderlini and M. Andersson and A. Andreianov and M. Andreotti and F. Archilli and A. Artamonov and M. Artuso and K. Arzymatov and E. Aslanides and M. Atzeni and B. Audurier and S. Bachmann and M. Bachmayer and Back, {J. J.} and S. Bifani and R. Calladine and N. Cooke and V. Duk and P. Ilten and J. Plews and D. Popov and N. Sahoo and A. Sergi and Slater, {M. W.} and Swallow, {P. N.} and Watson, {N. K.}",

note = "Funding Information: We express our gratitude to our colleagues in the CERN accelerator departments for the excellent performance of the LHC. We thank the technical and administrative staff at the LHCb institutes. We acknowledge support from CERN and from the national agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); MOST and NSFC (China); CNRS/IN2P3 (France); BMBF, DFG and MPG (Germany); INFN (Italy); NWO (Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MSHE (Russia); MICINN (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and NSF (USA). We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland), and NERSC (USA). We are indebted to the communities behind the multiple open-source software packages on which we depend. Individual groups or members have received support from ARC and ARDC (Australia); AvH Foundation (Germany); EPLANET, Marie Sk{\l}odowska-Curie Actions and ERC (European Union); A*MIDEX, ANR, IPhU, and Labex P2IO, and R{\'e}gion Auvergne-Rh{\'o}ne-Alpes (France); Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP, Fundamental Research Funds for the Central Universities, and Sci. & Tech. Program of Guangzhou (China); RFBR, RSF, and Yandex LLC (Russia); GVA, XuntaGal, and GENCAT (Spain); the Leverhulme Trust, the Royal Society, and UKRI (United Kingdom). Publisher Copyright: {\textcopyright} 2022 CERN.",

year = "2022",

month = may,

day = "13",

doi = "10.1103/PhysRevLett.128.191803",

language = "English",

volume = "128",

journal = "Physical Review Letters",

issn = "0031-9007",

publisher = "American Physical Society (APS)",

number = "19",

}

TY - JOUR

T1 - Observation of the decay Λb0 → Λc+ τ- ν̄τ

AU - LHCb Collaboration

AU - Aaij, R.

AU - Abdelmotteleb, A. S.W.

AU - Beteta, C. Abellán

AU - Abudinén, F.

AU - Ackernley, T.

AU - Adeva, B.

AU - Adinolfi, M.

AU - Afsharnia, H.

AU - Agapopoulou, C.

AU - Aidala, C. A.

AU - Aiola, S.

AU - Ajaltouni, Z.

AU - Akar, S.

AU - Albrecht, J.

AU - Alessio, F.

AU - Alexander, M.

AU - Albero, A. Alfonso

AU - Aliouche, Z.

AU - Alkhazov, G.

AU - Cartelle, P. Alvarez

AU - Amato, S.

AU - Amey, J. L.

AU - Amhis, Y.

AU - An, L.

AU - Anderlini, L.

AU - Andersson, M.

AU - Andreianov, A.

AU - Andreotti, M.

AU - Archilli, F.

AU - Artamonov, A.

AU - Artuso, M.

AU - Arzymatov, K.

AU - Aslanides, E.

AU - Atzeni, M.

AU - Audurier, B.

AU - Bachmann, S.

AU - Bachmayer, M.

AU - Back, J. J.

AU - Bifani, S.

AU - Calladine, R.

AU - Cooke, N.

AU - Duk, V.

AU - Ilten, P.

AU - Plews, J.

AU - Popov, D.

AU - Sahoo, N.

AU - Sergi, A.

AU - Slater, M. W.

AU - Swallow, P. N.

AU - Watson, N. K.

N1 - Funding Information: We express our gratitude to our colleagues in the CERN accelerator departments for the excellent performance of the LHC. We thank the technical and administrative staff at the LHCb institutes. We acknowledge support from CERN and from the national agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); MOST and NSFC (China); CNRS/IN2P3 (France); BMBF, DFG and MPG (Germany); INFN (Italy); NWO (Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MSHE (Russia); MICINN (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and NSF (USA). We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland), and NERSC (USA). We are indebted to the communities behind the multiple open-source software packages on which we depend. Individual groups or members have received support from ARC and ARDC (Australia); AvH Foundation (Germany); EPLANET, Marie Skłodowska-Curie Actions and ERC (European Union); A*MIDEX, ANR, IPhU, and Labex P2IO, and Région Auvergne-Rhóne-Alpes (France); Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP, Fundamental Research Funds for the Central Universities, and Sci. & Tech. Program of Guangzhou (China); RFBR, RSF, and Yandex LLC (Russia); GVA, XuntaGal, and GENCAT (Spain); the Leverhulme Trust, the Royal Society, and UKRI (United Kingdom). Publisher Copyright: © 2022 CERN.

PY - 2022/5/13

Y1 - 2022/5/13

N2 - The first observation of the semileptonic b-baryon decay Λb0→Λc+τ-ν̄τ, with a significance of 6.1σ, 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-ν̄τ)/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-ν̄τ)=(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-ν̄τ)/B(Λb0→Λc+μ-ν̄μ) is derived to be 0.242±0.026±0.040±0.059, where the external branching fraction uncertainty from the channel Λb0→Λc+μ-ν̄μ contributes to the last term. This result is in agreement with the standard model prediction.

AB - The first observation of the semileptonic b-baryon decay Λb0→Λc+τ-ν̄τ, with a significance of 6.1σ, 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-ν̄τ)/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-ν̄τ)=(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-ν̄τ)/B(Λb0→Λc+μ-ν̄μ) is derived to be 0.242±0.026±0.040±0.059, where the external branching fraction uncertainty from the channel Λb0→Λc+μ-ν̄μ contributes to the last term. This result is in agreement with the standard model prediction.

UR - http://www.scopus.com/inward/record.url?scp=85130325891&partnerID=8YFLogxK

U2 - 10.1103/PhysRevLett.128.191803

DO - 10.1103/PhysRevLett.128.191803

M3 - Article

C2 - 35622037

AN - SCOPUS:85130325891

SN - 0031-9007

VL - 128

JO - Physical Review Letters

JF - Physical Review Letters

IS - 19

M1 - 191803

ER -