Abstract
This Letter presents the observation of the rare Z boson decay Z→ψ + -. Here, ψ represents contributions from direct J/ψ and ψ(2S)→J/ψX, + - is a pair of electrons or muons, and the J/ψ meson is detected via its decay to μ+μ-. The sample of proton-proton collision data, collected by the CMS experiment at the LHC at a center-of-mass energy of 13 TeV, corresponds to an integrated luminosity of 35.9 fb-1. The signal is observed with a significance in excess of 5 standard deviations. After subtraction of the ψ(2S)→J/ψX contribution, the ratio of the branching fraction of the exclusive decay Z→J/ψ + - to the decay Z→μ+μ-μ+μ- within a fiducial phase space is measured to be B(Z→J/ψ + -)/B(Z→μ+μ-μ+μ-)=0.67±0.18(stat)±0.05(syst).
| Original language | English |
|---|---|
| Article number | 141801 |
| Journal | Physical Review Letters |
| Volume | 121 |
| Issue number | 14 |
| DOIs | |
| Publication status | Published - 4 Oct 2018 |
Bibliographical note
Publisher Copyright:© 2018 CERN, for the CMS Collaboration.
Funding
We congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC and thank the technical and administrative staffs at CERN and at other CMS institutes for their contributions to the success of the CMS effort. In addition, we gratefully acknowledge the computing centers and personnel of the Worldwide LHC Computing Grid for delivering so effectively the computing infrastructure essential to our analyses. Finally, we acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, FAPERGS, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); SENESCYT (Ecuador); MoER, ERC IUT, and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); NKFIA (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS, RFBR, and NRC KI (Russia); MESTD (Serbia); SEIDI, CPAN, PCTI, and FEDER (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (USA).
| Funders | Funder number |
|---|---|
| Not added | ST/I505580/1, ST/K003542/1, ST/M004775/1, ST/L005603/1, ST/N001273/1, ST/I003622/1, ST/J005479/1, ST/N000242/1 |
| CNRS/IN2P3 | |
| CPAN | |
| ERC IUT | |
| LNS | |
| MESTD | |
| MON | |
| MSES | |
| MSHE | |
| MoER | |
| PCTI | |
| STAR | |
| Swiss Funding Agencies | |
| TUBITAK | |
| ThEPCenter | |
| UASLP-FAI | |
| National Science Foundation | |
| U.S. Department of Energy | |
| Hispanics in Philanthropy | |
| CS Fund | |
| Departamento Administrativo de Ciencia, Tecnología e Innovación (COLCIENCIAS) | |
| California Earthquake Authority | |
| Secretaría de Educación Pública | |
| Türkiye Atom Enerjisi Kurumu | |
| Louisiana Academy of Sciences | |
| Missouri University of Science and Technology | |
| CERN | |
| College of Arts and Sciences, University of Nebraska-Lincoln | |
| Norwegian Sequencing Centre | |
| Institute for the Promotion of Teaching Science and Technology | |
| Mountain Equipment Co-operative | |
| Science and Technology Facilities Council | ST/F007434/1, ST/J004871/1, GRIDPP |
| Royal Astronomical Society | |
| Ministry of Education - Singapore | |
| Department of Atomic Energy, Government of India | |
| Science Foundation Ireland | |
| Helmholtz-Gemeinschaft | |
| Deutsche Forschungsgemeinschaft | |
| Fundação de Amparo à Pesquisa do Estado de São Paulo | |
| National Natural Science Foundation of China | |
| Research Promotion Foundation | |
| Fundação para a Ciência e a Tecnologia | |
| Russian Foundation for Basic Research | |
| Coordenação de Aperfeiçoamento de Pessoal de Nível Superior | |
| Academy of Finland | |
| Bundesministerium für Bildung und Forschung | |
| Austrian Science Fund | |
| Fonds De La Recherche Scientifique - FNRS | |
| Fonds Wetenschappelijk Onderzoek | |
| Consejo Nacional de Ciencia y Tecnología | |
| Bundesministerium für Wissenschaft, Forschung und Wirtschaft | |
| General Secretariat for Research and Technology | |
| Conselho Nacional de Desenvolvimento Científico e Tecnológico | |
| Ministry of Science, ICT and Future Planning | |
| Ministry of Science and Technology | |
| National Research Foundation of Korea | |
| Joint Institute for Nuclear Research | |
| Instituto Nazionale di Fisica Nucleare | |
| National Science and Technology Development Agency | Thailand |
| Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul | |
| Secretaría de Educación Superior, Ciencia, Tecnología e Innovación | |
| Universiti Malaya | |
| Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro | |
| Ministry for Business Innovation and Employment | |
| National Academy of Sciences of Ukraine | |
| Ministry of Education and Science | |
| Institute for Research in Fundamental Sciences | |
| Benemérita Universidad Autónoma de Puebla | |
| Secretaría de Estado de Investigación, Desarrollo e Innovación | |
| European Regional Development Fund | |
| State Atomic Energy Corporation ROSATOM | |
| Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional | |
| Pakistan Atomic Energy Commission | |
| State Fund for Fundamental Research of Ukraine | |
| Department of Science and Technology, Government of West Bengal | |
| Nemzeti Kutatási, Fejlesztési és Innovaciós Alap | |
| National Research Center "Kurchatov Institute" |