Abstract
A search for a signal consistent with the type-III seesaw mechanism in events with three or more electrons or muons is presented. The data sample consists of proton-proton collisions at s=13 TeV collected by the CMS experiment at the LHC in 2016 and corresponds to an integrated luminosity of 35.9 fb-1. Selection criteria based on the number of leptons and the invariant mass of oppositely charged lepton pairs are used to distinguish the signal from the standard model background. The observations are consistent with the expectations from standard model processes. The results are used to place limits on the production of heavy fermions of the type-III seesaw model as a function of the branching ratio to each lepton flavor. In the scenario of equal branching fractions to each lepton flavor, heavy fermions with masses below 840 GeV are excluded. This is the most sensitive probe to date of the type-III seesaw mechanism.
| Original language | English |
|---|---|
| Article number | 221802 |
| Journal | Physical Review Letters |
| Volume | 119 |
| Issue number | 22 |
| DOIs | |
| Publication status | Published - 1 Dec 2017 |
Bibliographical note
Publisher Copyright:© 2017 CERN, for the CMS Collaboration.
Funding
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, 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); OTKA and NIH (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 RAEP (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). 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, 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); OTKA and NIH (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 RAEP (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 |
|---|---|
| CNRS/IN2P3 | |
| CPAN | |
| ERC IUT | |
| LNS | |
| MESTD | |
| MON | |
| MSES | |
| MSHE | |
| MoER | |
| PCTI | |
| RAEP | |
| STAR | |
| Swiss Funding Agencies | |
| TUBITAK | |
| ThEPCenter | |
| UASLP-FAI | |
| National Science Foundation | 1606321, 1607096, 1151640, 1506168, 1506130, 1508869 |
| National Institutes of Health | |
| U.S. Department of Energy | |
| Hispanics in Philanthropy | |
| CS Fund | |
| California Department of Fish and Game | |
| Departamento Administrativo de Ciencia, Tecnología e Innovación | |
| Children's Specialists Foundation | |
| 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 | PP/E000479/1, GRIDPP, ST/H000925/1 |
| 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 | |
| Chinese Academy of Sciences | |
| Austrian Science Fund | |
| Fonds De La Recherche Scientifique - FNRS | |
| Ministry of Education, Ethiopia | |
| Fonds Wetenschappelijk Onderzoek | |
| Consejo Nacional de Ciencia y Tecnología | |
| Bundesministerium für Wissenschaft, Forschung und Wirtschaft | |
| General Secretariat for Research and Technology | |
| Országos Tudományos Kutatási Alapprogramok | |
| 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 | |
| Instituto Politécnico de Macau | |
| Norsk Sykepleierforbund | |
| National Science and Technology Development Agency | Thailand |
| 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 | |
| Foundation for Promotion of Material Science and Technology of Japan | |
| Benemérita Universidad Autónoma de Puebla | |
| Ministério da Educação | |
| Commissariat à l'Énergie Atomique et aux Énergies Alternatives | |
| Bundesministerium für Bildung und Frauen | |
| 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 |