Search for an L-mu - L-tau gauge boson using Z -> 4 mu events in proton-proton collisions at root s=13 TeV
BMWFW ; FWF ; FNRS ; FWO (Belgium) ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) ; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) ; Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) ; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) ; MES (Bulgaria) ; MOST ; NSFC (China) ; COLCIEN-CIAS (Colombia) ; CSF (Croatia) ; SENESCYT (Ecuador) ; MoER ; ERDF (Estonia) ; Academy of Finland ; MEC ; CEA ; CNRS/IN2P3 (France) ; BMBF ; DFG ; HGF (Germany) ; GSRT (Greece) ; NKFIA (Hungary) ; DAE ; DST ; IPM ; SFI (Ireland) ; INFN (Italy) ; NRF (Republic of Korea) ; MOE ; UM (Malaysia) ; BUAP, CINVESTAV ; CONACYT ; UASLP-FAI (Mexico) ; MBIE (New Zealand) ; PAEC (Pakistan) ; MSHE ; FCT (Portugal) ; JINR (Dubna) ; RFBR ; MESTD (Serbia) ; SEIDI ; FEDER (Spain) ; Swiss Funding Agencies (Switzerland) ; NSTDA (Thailand) ; TUBITAK ; TAEK ; NASU ; SFFR (Ukraine) ; DOE ; NSF (USA) ; Marie-Curie program ; European Research Council ; Horizon 2020 Grant ; Leventis Foundation ; Alfred P. Sloan Foundation ; Alexander von Hum-boldt Foundation ; Belgian Federal Science Policy Office ; Fonds pour la Formation a la Recherche dans l'Industrie et dans l'Agriculture(FRIA-Belgium) ; Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium) ; FWO (Belgium) under the Excellence of Science - EOS ; Ministry of Education, Youth and Sports (MEYS) of the Czech Republic ; Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences ; Council of Science and Industrial Research, India ; HOMING PLUS program of the Foundation for Polish Science ; European Union, Regional Development Fund ; Sonata-bis ; National Priorities Research Program by Qatar National Research Fund ; Programa Severo Ochoa del Principado de Asturias ; Thalis and Aristeia programs ; EU-ESF ; Greek NSRF ; Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University ; Welch Foundation ; Weston Havens Foundation (USA) ; Horizon 2020 Grant: 675440 ; FWO (Belgium) under the Excellence of Science - EOS: 30820817 ; Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences: 123842 ; Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences: 123959 ; Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences: 124845 ; Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences: 124850 ; Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences: 125105 ; European Union, Regional Development Fund: Harmonia 2014/14/M/ST2/00428 ; European Union, Regional Development Fund: 2014/13/B/ST2/02543 ; European Union, Regional Development Fund: 2014/15/B/ST2/03998 ; European Union, Regional Development Fund: 2015/19/B/ST2/02861 ; Sonata-bis: 2012/07/E/ST2/01406 ; National Priorities Research Program by Qatar National Research Fund: MDM-2015-0509 ; Welch Foundation: C-1845 ; A search for a narrow Z' gauge boson with a mass between 5 and 70 GeV resulting from an L-mu - L-tau U (1) local gauge symmetry is reported. Theories that predict such a particle have been proposed as an explanation of various experimental discrepancies, including the lack of a dark matter signal in direct-detection experiments, tension in the measurement of the anomalous magnetic moment of the muon, and reports of possible lepton flavor universality violation in B meson decays. A data sample of proton-proton collisions at a center-of-mass energy of 13 TeV is used, corresponding to an integrated luminosity of 77.3 fb(-1) recorded in 2016 and 2017 by the CMS detector at the LHC. Events containing four muons with an invariant mass near the standard model Z boson mass are analyzed, and the selection is further optimized to be sensitive to the events that may contain Z -> Z'mu mu -> 4 mu decays. The event yields are consistent with the standard model predictions. Upper limits of 10(-8)-10(-7) at 95% confidence level are set on the product of branching fractions B(Z -> Z'mu mu)B(Z' -> mu mu), depending on the Z' mass, which excludes a Z' boson coupling strength to muons above 0.004-0.3. These are the first dedicated limits on L-mu - L-tau models at the LHC and result in a significant increase in the excluded model parameter space. The results of this search may also be used to constrain the coupling strength of any light Z' gauge boson to muons. (C) 2019 The Author(s). Published by Elsevier B.V.