Search for lepton flavour violating decays of heavy resonances and quantum black holes to an e mu pair in proton-proton collisions at root s=8 TeV
BMWFW (Austria) ; FWF (Austria) ; FNRS (Belgium) ; 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) ; CERN ; CAS (China) ; MoST (China) ; NSFC (China) ; COLCIENCIAS (Colombia) ; MSES (Croatia) ; CSF (Croatia) ; RPF (Cyprus) ; MoER (Estonia) ; ERC IUT (Estonia) ; ERDF (Estonia) ; Academy of Finland (Finland) ; MEC (Finland) ; HIP (Finland) ; CEA (France) ; CNRS/IN2P3 (France) ; BMBF (Germany) ; DFG (Germany) ; HGF (Germany) ; GSRT (Greece) ; OTKA (Hungary) ; NIH (Hungary) ; DAE (India) ; DST (India) ; IPM (Iran) ; SFI (Ireland) ; INFN (Italy) ; MSIP (Republic of Korea) ; NRF (Republic of Korea) ; LAS (Lithuania) ; MOE (Malaysia) ; UM (Malaysia) ; CINVESTAV (Mexico) ; CONACYT (Mexico) ; SEP (Mexico) ; UASLP-FAI (Mexico) ; MBIE (NewZealand) ; PAEC (Pakistan) ; MSHE (Poland) ; NSC (Poland) ; FCT (Portugal) ; JINR (Dubna) ; MON (Russia) ; RosAtom (Russia) ; RAS (Russia) ; RFBR (Russia) ; MESTD (Serbia) ; SEIDI (Spain) ; CPAN (Spain) ; Swiss Funding Agencies (Switzerland) ; MST (Taipei) ; ThEPCenter (Thailand) ; IPST (Thailand) ; STAR (Thailand) ; NSTDA (Thailand) ; TUBITAK (Turkey) ; TAEK (Turkey) ; NASU (Ukraine) ; SFFR (Ukraine) ; STFC (United Kingdom) ; DOE (USA) ; NSF (USA) ; Marie-Curie programme ; European Research Council ; EPLANET (European Union) ; Leventis Foundation ; A. P. Sloan Foundation ; Alexander von Humboldt 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) ; Ministry of Education, Youth and Sports (MEYS) of the Czech Republic ; Council of Science and Industrial Research, India ; HOMING PLUS programme of the Foundation for Polish Science ; European Union, Regional Development Fund ; Mobility Plus programme of the Ministry of Science and Higher Education (Poland) ; OPUS programme of the National Science Center (Poland) ; MIUR (Italy) ; Thalis programme - EU-ESF ; Aristeia programme - EU-ESF ; Greek NSRF ; National Priorities Research Program by Qatar National Research Fund ; Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University (Thailand) ; Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand) ; Welch Foundation ; Science and Technology Facilities Council ; MIUR (Italy): 20108T4XTM ; Welch Foundation: C-1845 ; Science and Technology Facilities Council: ST/J004871/1 ; Science and Technology Facilities Council: ST/I003622/1 ; Science and Technology Facilities Council: ST/M004775/1 GRIDPP ; Science and Technology Facilities Council: ST/K003542/1 GRID PP ; Science and Technology Facilities Council: ST/M004775/1 ; Science and Technology Facilities Council: PP/E000479/1 ; Science and Technology Facilities Council: ST/N000250/1 ; Science and Technology Facilities Council: PP/E002803/1 ; Science and Technology Facilities Council: CMS ; Science and Technology Facilities Council: GRIDPP ; Science and Technology Facilities Council: ST/H000925/1 ; Science and Technology Facilities Council: ST/N000242/1 ; Science and Technology Facilities Council: ST/K003542/1 ; Science and Technology Facilities Council: ST/J005479/1 ; Science and Technology Facilities Council: ST/H000925/2 ; Science and Technology Facilities Council: ST/K001531/1 ; Science and Technology Facilities Council: ST/I000305/1 ; Science and Technology Facilities Council: ST/K003542/1 GRIDPP ; Science and Technology Facilities Council: ST/I003622/1 GRIDPP ; Science and Technology Facilities Council: ST/K001639/1 ; Science and Technology Facilities Council: ST/L005603/1 ; Science and Technology Facilities Council: ST/K003224/1 CMS Upgrades ; Science and Technology Facilities Council: ST/K001256/1 ; Science and Technology Facilities Council: ST/N001273/1 ; Science and Technology Facilities Council: ST/K001639/1 CMS Upgrades ; Science and Technology Facilities Council: ST/M002020/1 ; A search for narrow resonances decaying to an electron and a muon is presented. The e mu mass spectrum is also investigated for non-resonant contributions from the production of quantum black holes (QBHs). The analysis is performed using data corresponding to an integrated luminosity of 19.7 fb(-1) collected in proton-proton collisions at a centre-of-mass energy of 8 TeV with the CMS detector at the LHC. With no evidence for physics beyond the standard model in the invariant mass spectrum of selected e mu pairs, upper limits are set at 95 % confidence level on the product of cross section and branching fraction for signals arising in theories with charged lepton flavour violation. In the search for narrow resonances, the resonant production of a tau sneutrino in R-parity violating supersymmetry is considered. The t sneutrino is excluded for masses below 1.28 TeV for couplings lambda(132) = lambda(231) = lambda(')(311) = 0.01, and below 2.30 TeV for lambda(132) = lambda(231) = 0.07 and lambda(')(311) = 0.11. These are the most stringent limits to date from direct searches at high-energy colliders. In addition, the resonance searches are interpreted in terms of a model with heavy partners of the Z boson and the photon. In a framework of TeV-scale quantum gravity based on a renormalization of Newton's constant, the search for non-resonant contributions to the e mu mass spectrum excludes QBH production below a threshold mass M-th of 1.99 TeV. In models that invoke extra dimensions, the bounds range from 2.36 TeV for one extra dimension to 3.63 TeV for six extra dimensions. This is the first search for QBHs decaying into the e mu final state.