Measurement of the Ratios of Branching Fractions R(D*) and R(D0)

LHCb Collaboration

doi:10.1103/PhysRevLett.131.111802

Measurement of the Ratios of Branching Fractions R(D^*) and R(D⁰)

LHCb Collaboration

Physics and Astronomy

Research output: Contribution to journal › Letter › peer-review

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Abstract

The ratios of branching fractions R(D^∗) ≡ B(B̅ → D^∗τ⁻ν̅_τ) / B(B̅→D^∗μ⁻ν̅_μ) and R(D⁰) ≡ B(B̅→D⁰τ⁻ν̅_τ ) / B(B̅→D⁰μ⁻ν̅_μ) are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb⁻¹ of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode τ⁻→ μ⁻ν_τ ν̅_μ . The measured values are R(D^∗) = 0.281 ± 0.018 ± 0.024 and R(D⁰) = 0.441 ± 0.060 ± 0.066 , where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is ρ = −0.43 . The results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the standard model.

Original language	English
Article number	111802
Number of pages	13
Journal	Physical Review Letters
Volume	131
Issue number	11
Early online date	13 Sept 2023
DOIs	https://doi.org/10.1103/PhysRevLett.131.111802
Publication status	Published - 15 Sept 2023

Bibliographical note

Acknowledgments:
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); MCID/IFA (Romania); 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), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), Polish WLCG (Poland) and NERSC (USA). We are indebted to the communities behind the multiple opensource software packages on which we depend. Individual groups or members have received support from ARC and ARDC (Australia); Minciencias (Colombia); AvH Foundation (Germany); EPLANET, Marie SkłodowskaCurie Actions and ERC (European Union); A*MIDEX, ANR, IPhU and Labex P2IO, and R´egion AuvergneRhône-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); GVA, XuntaGal, GENCAT, and Prog. Atracción Talento, CM (Spain); SRC (Sweden); the Leverhulme Trust, the Royal Society, and UKRI (United Kingdom).

ASJC Scopus subject areas

General Physics and Astronomy

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Cite this

@article{57faa1ab8f554c6085d6de0a3570354c,

title = "Measurement of the Ratios of Branching Fractions R(D*) and R(D0)",

abstract = "The ratios of branching fractions R(D∗) ≡ B(B̅ → D∗τ−ν̅τ) / B(B̅→D∗μ−ν̅μ) and R(D0) ≡ B(B̅→D0τ−ν̅τ ) / B(B̅→D0μ−ν̅μ) are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb−1 of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode τ−→ μ− ντ ν̅μ . The measured values are R(D∗) = 0.281 ± 0.018 ± 0.024 and R(D0) = 0.441 ± 0.060 ± 0.066 , where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is ρ = −0.43 . The results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the standard model. ",

author = "{LHCb Collaboration} and R. Aaij and Abdelmotteleb, {A. S.W.} and {Abellan Beteta}, C. and F. Abudin{\'e}n and T. Ackernley and B. Adeva and M. Adinolfi and P. Adlarson and H. Afsharnia and C. Agapopoulou and Aidala, {C. A.} and Z. Ajaltouni and S. Akar and K. Akiba and P. Albicocco and J. Albrecht and F. Alessio and M. Alexander and {Alfonso Albero}, A. and Z. Aliouche and {Alvarez Cartelle}, P. and R. Amalric 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 D. Andreou and D. Ao and F. Archilli and A. Artamonov and M. Artuso and E. Aslanides and M. Atzeni and B. Audurier and {Bachiller Perea}, {I. B.} 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 Thompson, {D. J.D.} and Watson, {N. K.}",

note = "Acknowledgments: 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); MCID/IFA (Romania); 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), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), Polish WLCG (Poland) and NERSC (USA). We are indebted to the communities behind the multiple opensource software packages on which we depend. Individual groups or members have received support from ARC and ARDC (Australia); Minciencias (Colombia); AvH Foundation (Germany); EPLANET, Marie Sk{\l}odowskaCurie Actions and ERC (European Union); A*MIDEX, ANR, IPhU and Labex P2IO, and R´egion AuvergneRh{\^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); GVA, XuntaGal, GENCAT, and Prog. Atracci{\'o}n Talento, CM (Spain); SRC (Sweden); the Leverhulme Trust, the Royal Society, and UKRI (United Kingdom). ",

year = "2023",

month = sep,

day = "15",

doi = "10.1103/PhysRevLett.131.111802",

language = "English",

volume = "131",

journal = "Physical Review Letters",

issn = "0031-9007",

publisher = "American Physical Society (APS)",

number = "11",

}

TY - JOUR

T1 - Measurement of the Ratios of Branching Fractions R(D*) and R(D0)

AU - LHCb Collaboration

AU - Aaij, R.

AU - Abdelmotteleb, A. S.W.

AU - Abellan Beteta, C.

AU - Abudinén, F.

AU - Ackernley, T.

AU - Adeva, B.

AU - Adinolfi, M.

AU - Adlarson, P.

AU - Afsharnia, H.

AU - Agapopoulou, C.

AU - Aidala, C. A.

AU - Ajaltouni, Z.

AU - Akar, S.

AU - Akiba, K.

AU - Albicocco, P.

AU - Albrecht, J.

AU - Alessio, F.

AU - Alexander, M.

AU - Alfonso Albero, A.

AU - Aliouche, Z.

AU - Alvarez Cartelle, P.

AU - Amalric, R.

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 - Andreou, D.

AU - Ao, D.

AU - Archilli, F.

AU - Artamonov, A.

AU - Artuso, M.

AU - Aslanides, E.

AU - Atzeni, M.

AU - Audurier, B.

AU - Bachiller Perea, I. B.

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 - Thompson, D. J.D.

AU - Watson, N. K.

N1 - Acknowledgments: 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); MCID/IFA (Romania); 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), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), Polish WLCG (Poland) and NERSC (USA). We are indebted to the communities behind the multiple opensource software packages on which we depend. Individual groups or members have received support from ARC and ARDC (Australia); Minciencias (Colombia); AvH Foundation (Germany); EPLANET, Marie SkłodowskaCurie Actions and ERC (European Union); A*MIDEX, ANR, IPhU and Labex P2IO, and R´egion AuvergneRhône-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); GVA, XuntaGal, GENCAT, and Prog. Atracción Talento, CM (Spain); SRC (Sweden); the Leverhulme Trust, the Royal Society, and UKRI (United Kingdom).

PY - 2023/9/15

Y1 - 2023/9/15

N2 - The ratios of branching fractions R(D∗) ≡ B(B̅ → D∗τ−ν̅τ) / B(B̅→D∗μ−ν̅μ) and R(D0) ≡ B(B̅→D0τ−ν̅τ ) / B(B̅→D0μ−ν̅μ) are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb−1 of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode τ−→ μ− ντ ν̅μ . The measured values are R(D∗) = 0.281 ± 0.018 ± 0.024 and R(D0) = 0.441 ± 0.060 ± 0.066 , where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is ρ = −0.43 . The results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the standard model.

AB - The ratios of branching fractions R(D∗) ≡ B(B̅ → D∗τ−ν̅τ) / B(B̅→D∗μ−ν̅μ) and R(D0) ≡ B(B̅→D0τ−ν̅τ ) / B(B̅→D0μ−ν̅μ) are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb−1 of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode τ−→ μ− ντ ν̅μ . The measured values are R(D∗) = 0.281 ± 0.018 ± 0.024 and R(D0) = 0.441 ± 0.060 ± 0.066 , where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is ρ = −0.43 . The results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the standard model.

UR - http://www.scopus.com/inward/record.url?scp=85172824713&partnerID=8YFLogxK

U2 - 10.1103/PhysRevLett.131.111802

DO - 10.1103/PhysRevLett.131.111802

M3 - Letter

C2 - 37774262

AN - SCOPUS:85172824713

SN - 0031-9007

VL - 131

JO - Physical Review Letters

JF - Physical Review Letters

IS - 11

M1 - 111802

ER -