Abstract
A measurement is reported of the ratio of branching fractions R(J/ψ)=B(Bc+→J/ψτ+ντ)/B(Bc+→J/ψμ+νμ), where the τ+ lepton is identified in the decay mode τ+→μ+νμντ. This analysis uses a sample of proton-proton collision data corresponding to 3.0 fb-1 of integrated luminosity recorded with the LHCb experiment at center-of-mass energies of 7 and 8 TeV. A signal is found for the decay Bc+→J/ψτ+ντ at a significance of 3 standard deviations corrected for systematic uncertainty, and the ratio of the branching fractions is measured to be R(J/ψ)=0.71±0.17(stat)±0.18(syst). This result lies within 2 standard deviations above the range of central values currently predicted by the standard model.
| Original language | English |
|---|---|
| Article number | 121801 |
| Journal | Physical Review Letters |
| Volume | 120 |
| Issue number | 12 |
| DOIs | |
| Publication status | Published - 23 Mar 2018 |
Funding
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); MinES and FASO (Russia); MinECo (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); 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 OSC (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 AvH Foundation (Germany), EPLANET, Marie Skłodowska-Curie Actions, and ERC (European Union), ANR, Labex P2IO, ENIGMASS, and OCEVU, and Région Auvergne-Rhône-Alpes (France), RFBR and Yandex LLC (Russia), GVA, XuntaGal, and GENCAT (Spain), Herchel Smith Fund, the Royal Society, the English-Speaking Union, and the Leverhulme Trust (United Kingdom). 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); MinES and FASO (Russia); MinECo (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); 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 OSC (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 AvH Foundation (Germany), EPLANET, Marie Sklodowska-Curie Actions, and ERC (European Union), ANR, Labex P2IO, ENIGMASS, and OCEVU, and Region Auvergne-Rhne-Alpes (France), RFBR and Yandex LLC (Russia), GVA, XuntaGal, and GENCAT (Spain), Herchel Smith Fund, the Royal Society, the English-Speaking Union, and the Leverhulme Trust (United Kingdom).
| Funders | Funder number |
|---|---|
| Not added | ST/J004332/1, ST/N000250/1, 1681016, ST/K003410/1, 1796908, ST/H006737/1, ST/N000463/1, ST/N000455/1, ST/L003163/1 |
| EPLANET | |
| Herchel Smith Fund | |
| MinES | |
| OCEVU | |
| XuntaGal | |
| Yandex LLC | |
| National Science Foundation | |
| California Department of Fish and Game | |
| Alexander von Humboldt-Stiftung | |
| Poultry Industry Council | |
| H2020 Marie Skłodowska-Curie Actions | |
| CERN | |
| Science and Technology Facilities Council | LHCb, GRIDPP, LHCb Upgrades, ST/N000242/1 |
| Leverhulme Trust | |
| Royal Society | |
| European Commission | |
| European Research Council | |
| Deutsches Elektronen-Synchrotron | |
| Deutsche Forschungsgemeinschaft | |
| Agence Nationale de la Recherche | |
| Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung | 166208 |
| National Natural Science Foundation of China | |
| Russian Foundation for Basic Research | |
| Coordenação de Aperfeiçoamento de Pessoal de Nível Superior | |
| Bundesministerium für Bildung und Forschung | |
| Kumoh National Institute of Technology | |
| Ministry of Science and Technology of the People's Republic of China | |
| Nederlandse Organisatie voor Wetenschappelijk Onderzoek | |
| Generalitat Valenciana | |
| Conselho Nacional de Desenvolvimento Científico e Tecnológico | |
| Instituto Nazionale di Fisica Nucleare | |
| Max-Planck-Gesellschaft | |
| Narodowe Centrum Nauki | |
| Narodowym Centrum Nauki | |
| Ministerstwo Nauki i Szkolnictwa Wyższego | |
| Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro | |
| Ministry of Science and Technology, Taiwan | |
| National Academy of Sciences of Ukraine | |
| Centre National de la Recherche Scientifique | |
| Financiadora de Estudos e Projetos | |
| Bundesministerium für Bildung und Frauen | |
| Région Auvergne-Rhône-Alpes | |
| Institut national de physique nucléaire et de physique des particules | |
| Federal Agency for Scientific Organizations | |
| Sociedad Española de Reumatología |
