PLB33312S0370-2693(17)30893-610.1016/j.physletb.2017.11.001The Author(s)ExperimentsFig. 1Leading order diagrams representing heavy composite Majorana neutrino production. The total interaction is the coherent sum of the gauge and contact interactions. Charge-conjugate reactions are implied. See Ref. [12].Fig. 1Fig. 2Production cross section in pp collisions at s=13TeV of the heavy composite Majorana neutrino via gauge and contact interactions as a function of Majorana mass at Λ=9TeV (top) and decay width of the heavy composite Majorana neutrino for Λ=9TeV as a function of its mass (bottom). The figures illustrate LO results of calculations based on Ref. [12].Fig. 2Fig. 3Data events in the eμqq‾′ control regions used to estimate the tt‾+tW contribution in the eeqq‾′ (left) and μμqq‾′ (right) channels, compared to the expectations of the background simulations. “Other” stands for the contribution from W+jets and diboson events. (For interpretation of the references to colour in this figure, the reader is referred to the web version of this article.)Fig. 3Fig. 4Distribution of the variable mℓℓJ for the data (black points), the estimated SM backgrounds (stacked filled histograms), and the signal (lines) with Λ=9 TeV and masses of Nℓ equal to 1.5 and 2.5 TeV, for the eeqq‾′ (left) and the μμqq‾′ (right) channels. “Other” stands for the contribution from W+jets and diboson events. The background uncertainties are the combined statistical and systematic uncertainties. (For interpretation of the references to colour in this figure, the reader is referred to the web version of this article.)Fig. 4Fig. 5The observed 95% CL upper limits (solid black lines) on σ(pp→ℓNℓ)B(Nℓ→ℓqq‾′), obtained in the analysis of the eeqq‾′ (left) and the μμqq‾′ (right) final states, as a function of the mass of the heavy composite Majorana neutrino, Nℓ. The corresponding expected limits are shown by the dotted lines, and the bands represent the expected variation of the limit to one and two standard deviation(s). The solid blue curve indicates the theoretical prediction of σ(pp→ℓNℓ)B(Nℓ→ℓqq‾′) for Λ=mNℓ. The uncertainty in the theoretical prediction is derived by taking into account the factorization and normalization scales. The light red textured curves give the theoretical predictions for three Λ values ranging from 6 to 12 TeV in steps of 3 TeV. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)Fig. 5Fig. 6The observed 95% CL lower limits (solid black lines) on the compositeness scale Λ, obtained in the analysis of the eeqq‾′ (left) and the μμqq‾′ (right) final states, as a function of the mass of the heavy composite Majorana neutrino, Nℓ. The dotted lines represent the corresponding expected limits and the bands, the expected variation to one and two standard deviation(s). The grey zone represents the phase space Λ<MNℓ, which is not allowed by the model.Fig. 6Table 1Number of events observed in data are compared to the expected background yields and those of a hypothetical heavy composite Majorana neutrino of mass 1.5 and 2.5 TeV, and Λ=9 TeV, given for all values of mℓℓJ (upper table) and for mℓℓJ>1.4 TeV (lower table). The expected signal yields are computed at LO accuracy. “Other” stands for the contribution from W+jets and diboson events. The background and signal simulation yields are given with both statistical and systematic uncertainties. Statistical uncertainties given as 0.0 correspond to values much smaller than the systematical uncertainty.Table 1Process (all mℓℓJ)eeqq‾′ (mean±stat±syst)μμqq‾′ (mean±stat±syst)tt‾+tW26±4±344±6±5Drell–Yan22±1±530±1±7Other3.3±0.8±0.14.7±0.9±0.4Total51±4±680±6±8Observed6488Nℓ (1.5 TeV)9.7±0.0±0.312.8±0.0±1.6Nℓ (2.5 TeV)2.4±0.0±0.13.2±0.0±0.4Process (mℓℓJ> 1.4 TeV)eeqq‾′ (mean±stat±syst)μμqq‾′ (mean±stat±syst)tt‾+tW2.8±1.5±0.92.9±1.8±1.3Drell–Yan3.2±0.3±2.04.3±0.4±2.7Other0.36±0.10±0.040.25±0.10±0.11Total6.4±1.5±2.27.5±1.8±3.0Observed810Nℓ (1.5 TeV)9.4±0.0±0.312.4±0.0±1.6Nℓ (2.5 TeV)2.4±0.0±0.13.2±0.0±0.4Search for a heavy composite Majorana neutrino in the final state with two leptons and two quarks at s=13TeVThe CMS Collaboration⋆A.M.SirunyanA.TumasyanYerevan Physics Institute, Yerevan, ArmeniaYerevan Physics InstituteYerevanArmeniaW.AdamF.AmbrogiE.AsilarT.BergauerJ.BrandstetterE.BrondolinM.DragicevicJ.EröM.FlechlM.FriedlR.Frühwirth1V.M.GheteJ.GrossmannN.HörmannJ.HrubecM.Jeitler1A.KönigI.KrätschmerD.LikoT.MadlenerI.MikulecE.PreeD.RabadyN.RadH.RohringerJ.Schieck1R.SchöfbeckM.SpanringD.SpitzbartJ.StraussW.WaltenbergerJ.WittmannC.-E.Wulz1M.ZaruckiInstitut für Hochenergiephysik, Wien, AustriaInstitut für HochenergiephysikWienAustria1Also at Vienna University of Technology, Vienna, Austria.V.ChekhovskyV.MossolovJ.Suarez GonzalezInstitute for Nuclear Problems, Minsk, BelarusInstitute for Nuclear ProblemsMinskBelarusE.A.De WolfX.JanssenJ.LauwersM.Van De KlundertH.Van HaevermaetP.Van MechelenN.Van RemortelA.Van SpilbeeckUniversiteit Antwerpen, Antwerpen, BelgiumUniversiteit AntwerpenAntwerpenBelgiumS.Abu ZeidF.BlekmanJ.D'HondtI.De BruynJ.De ClercqK.DerooverG.FlourisS.LowetteS.MoortgatL.MoreelsA.OlbrechtsQ.PythonK.SkovpenS.TavernierW.Van DoninckP.Van MuldersI.Van ParijsVrije Universiteit Brussel, Brussel, BelgiumVrije Universiteit BrusselBrusselBelgiumH.BrunB.ClerbauxG.De LentdeckerH.DelannoyG.FasanellaL.FavartR.GoldouzianA.GrebenyukG.KarapostoliT.LenziJ.LueticT.MaerschalkA.MarinovA.Randle-condeT.SevaC.Vander VeldeP.VanlaerD.VanneromR.YonamineF.ZenoniF.Zhang2Université Libre de Bruxelles, Bruxelles, BelgiumUniversité Libre de BruxellesBruxellesBelgium2Also at State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China.A.CimminoT.CornelisD.DoburA.FagotM.GulI.KhvastunovD.PoyrazS.SalvaM.TytgatW.VerbekeN.ZaganidisGhent University, Ghent, BelgiumGhent UniversityGhentBelgiumH.BakhshiansohiO.BonduS.BrochetG.BrunoA.CaudronS.De VisscherC.DelaereM.DelcourtB.FrancoisA.GiammancoA.JafariM.KommG.KrintirasV.LemaitreA.MagitteriA.MertensM.MusichK.PiotrzkowskiL.QuertenmontM.Vidal MaronoS.WertzUniversité Catholique de Louvain, Louvain-la-Neuve, BelgiumUniversité Catholique de LouvainLouvain-la-NeuveBelgiumN.BeliyUniversité de Mons, Mons, BelgiumUniversité de MonsMonsBelgiumW.L.Aldá JúniorF.L.AlvesG.A.AlvesL.BritoC.HenselA.MoraesM.E.PolP.Rebello TelesCentro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, BrazilCentro Brasileiro de Pesquisas FisicasRio de JaneiroBrazilE.Belchior Batista Das ChagasW.CarvalhoJ.Chinellato3A.CustódioE.M.Da CostaG.G.Da Silveira4D.De Jesus DamiaoS.Fonseca De SouzaL.M.Huertas GuativaH.MalbouissonM.Melo De AlmeidaC.Mora HerreraL.MundimH.NogimaA.SantoroA.SznajderE.J.Tonelli Manganote3F.Torres Da Silva De AraujoA.Vilela PereiraUniversidade do Estado do Rio de Janeiro, Rio de Janeiro, BrazilUniversidade do Estado do Rio de JaneiroRio de JaneiroBrazil3Also at Universidade Estadual de Campinas, Campinas, Brazil.4Also at Universidade Federal de Pelotas, Pelotas, Brazil.S.AhujaaC.A.BernardesaT.R.Fernandez Perez TomeiaE.M.GregoresbP.G.MercadantebC.S.MoonaS.F.NovaesaSandra S.PadulaaD.Romero AbadbJ.C.Ruiz VargasaaUniversidade Estadual Paulista, São Paulo, BrazilUniversidade Estadual PaulistaSão PauloBrazilbUniversidade Federal do ABC, São Paulo, BrazilUniversidade Federal do ABCSão PauloBrazilA.AleksandrovR.HadjiiskaP.IaydjievM.MishevaM.RodozovS.StoykovaG.SultanovM.VutovaInstitute for Nuclear Research and Nuclear Energy of Bulgaria Academy of Sciences, BulgariaInstitute for Nuclear Research and Nuclear Energy of Bulgaria Academy of SciencesBulgariaA.DimitrovI.GlushkovL.LitovB.PavlovP.PetkovUniversity of Sofia, Sofia, BulgariaUniversity of SofiaSofiaBulgariaW.Fang5X.Gao5Beihang University, Beijing, ChinaBeihang UniversityBeijingChina5Also at Université Libre de Bruxelles, Bruxelles, Belgium.M.AhmadJ.G.BianG.M.ChenH.S.ChenM.ChenY.ChenC.H.JiangD.LeggatZ.LiuF.RomeoS.M.ShaheenA.SpieziaJ.TaoC.WangZ.WangE.YazganH.ZhangJ.ZhaoInstitute of High Energy Physics, Beijing, ChinaInstitute of High Energy PhysicsBeijingChinaY.BanG.ChenQ.LiS.LiuY.MaoS.J.QianD.WangZ.XuState Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, ChinaState Key Laboratory of Nuclear Physics and TechnologyPeking UniversityBeijingChinaC.AvilaA.CabreraL.F.Chaparro SierraC.FlorezC.F.González HernándezJ.D.Ruiz AlvarezUniversidad de Los Andes, Bogota, ColombiaUniversidad de Los AndesBogotaColombiaN.GodinovicD.LelasI.PuljakP.M.Ribeiro CiprianoT.SculacUniversity of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Split, CroatiaUniversity of SplitFaculty of Electrical Engineering, Mechanical Engineering and Naval ArchitectureSplitCroatiaZ.AntunovicM.KovacUniversity of Split, Faculty of Science, Split, CroatiaUniversity of SplitFaculty of ScienceSplitCroatiaV.BrigljevicD.FerencekK.KadijaB.MesicT.SusaInstitute Rudjer Boskovic, Zagreb, CroatiaInstitute Rudjer BoskovicZagrebCroatiaM.W.AtherA.AttikisG.MavromanolakisJ.MousaC.NicolaouF.PtochosP.A.RazisH.RykaczewskiUniversity of Cyprus, Nicosia, CyprusUniversity of CyprusNicosiaCyprusM.Finger6M.FingerJr.6Charles University, Prague, Czech RepublicCharles UniversityPragueCzech Republic6Also at Joint Institute for Nuclear Research, Dubna, Russia.E.Carrera JarrinUniversidad San Francisco de Quito, Quito, EcuadorUniversidad San Francisco de QuitoQuitoEcuadorY.Assran78M.A.Mahmoud98A.Mahrous10Academy of Scientific Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, EgyptAcademy of Scientific Research and Technology of the Arab Republic of EgyptEgyptian Network of High Energy PhysicsCairoEgypt7Also at Suez University, Suez, Egypt.8Now at British University in Egypt, Cairo, Egypt.9Also at Fayoum University, El-Fayoum, Egypt.10Now at Helwan University, Cairo, Egypt.R.K.DewanjeeM.KadastikL.PerriniM.RaidalA.TikoC.VeelkenNational Institute of Chemical Physics and Biophysics, Tallinn, EstoniaNational Institute of Chemical Physics and BiophysicsTallinnEstoniaP.EerolaJ.PekkanenM.VoutilainenDepartment of Physics, University of Helsinki, Helsinki, FinlandDepartment of PhysicsUniversity of HelsinkiHelsinkiFinlandJ.HärkönenT.JärvinenV.KarimäkiR.KinnunenT.LampénK.Lassila-PeriniS.LehtiT.LindénP.LuukkaE.TuominenJ.TuominiemiE.TuovinenHelsinki Institute of Physics, Helsinki, FinlandHelsinki Institute of PhysicsHelsinkiFinlandJ.TalvitieT.TuuvaLappeenranta University of Technology, Lappeenranta, FinlandLappeenranta University of TechnologyLappeenrantaFinlandM.BesanconF.CoudercM.DejardinD.DenegriJ.L.FaureF.FerriS.GanjourS.GhoshA.GivernaudP.GrasG.Hamel de MonchenaultP.JarryI.KucherE.LocciM.MachetJ.MalclesJ.RanderA.RosowskyM.Ö.SahinM.TitovIRFU, CEA, Université Paris-Saclay, Gif-sur-Yvette, FranceIRFUCEAUniversité Paris-SaclayGif-sur-YvetteFranceA.AbdulsalamI.AntropovS.BaffioniF.BeaudetteP.BussonL.CadamuroC.CharlotO.DavignonR.Granier de CassagnacM.JoS.LisniakA.LobanovM.NguyenC.OchandoG.OrtonaP.PaganiniP.PigardS.RegnardR.SalernoY.SiroisA.G.Stahl LeitonT.StreblerY.YilmazA.ZabiA.ZghicheLaboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Université Paris-Saclay, Palaiseau, FranceLaboratoire Leprince-RinguetEcole polytechniqueCNRS/IN2P3Université Paris-SaclayPalaiseauFranceJ.-L.Agram11J.AndreaD.BlochJ.-M.BromM.ButtignolE.C.ChabertN.ChanonC.CollardE.Conte11X.CoubezJ.-C.Fontaine11D.GeléU.GoerlachA.-C.Le BihanP.Van HoveUniversité de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, FranceUniversité de StrasbourgCNRSIPHC UMR 7178StrasbourgF-67000France11Also at Université de Haute Alsace, Mulhouse, France.S.GadratCentre de Calcul de l'Institut National de Physique Nucleaire et de Physique des Particules, CNRS/IN2P3, Villeurbanne, FranceCentre de Calcul de l'Institut National de Physique Nucleaire et de Physique des ParticulesCNRS/IN2P3VilleurbanneFranceS.BeauceronC.BernetG.BoudoulR.ChiericiD.ContardoB.CourbonP.DepasseH.El MamouniJ.FayL.FincoS.GasconM.GouzevitchG.GrenierB.IlleF.LagardeI.B.LaktinehM.LethuillierL.MirabitoA.L.PequegnotS.PerriesA.Popov12V.SordiniM.Vander DoncktS.ViretUniversité de Lyon, Université Claude Bernard Lyon 1, CNRS-IN2P3, Institut de Physique Nucléaire de Lyon, Villeurbanne, FranceUniversité de LyonUniversité Claude Bernard Lyon 1CNRS-IN2P3Institut de Physique Nucléaire de LyonVilleurbanneFrance12Also at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia.T.Toriashvili13Georgian Technical University, Tbilisi, GeorgiaGeorgian Technical UniversityTbilisiGeorgia13Also at Tbilisi State University, Tbilisi, Georgia.Z.Tsamalaidze6Tbilisi State University, Tbilisi, GeorgiaTbilisi State UniversityTbilisiGeorgiaC.AutermannS.BeranekL.FeldM.K.KieselK.KleinM.LipinskiM.PreutenC.SchomakersJ.SchulzT.VerlageRWTH Aachen University, I. Physikalisches Institut, Aachen, GermanyRWTH Aachen UniversityI. Physikalisches InstitutAachenGermanyA.AlbertM.BrodskiE.Dietz-LaursonnD.DuchardtM.EndresM.ErdmannS.ErdwegT.EschR.FischerA.GüthM.HamerT.HebbekerC.HeidemannK.HoepfnerS.KnutzenM.MerschmeyerA.MeyerP.MilletS.MukherjeeM.OlschewskiK.PadekenT.PookM.RadziejH.ReithlerM.RiegerF.ScheuchL.SonnenscheinD.TeyssierS.ThüerRWTH Aachen University, III. Physikalisches Institut A, Aachen, GermanyRWTH Aachen UniversityIII. Physikalisches Institut AAachenGermanyG.FlüggeB.KargollT.KressA.KünskenJ.LingemannT.MüllerA.NehrkornA.NowackC.PistoneO.PoothA.Stahl14RWTH Aachen University, III. Physikalisches Institut B, Aachen, GermanyRWTH Aachen UniversityIII. Physikalisches Institut BAachenGermany14Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland.M.Aldaya MartinT.ArndtC.AsawatangtrakuldeeK.BeernaertO.BehnkeU.BehrensA.A.Bin AnuarK.Borras15V.BottaA.CampbellP.ConnorC.Contreras-CampanaF.CostanzaC.Diez PardosG.EckerlinD.EcksteinT.EichhornE.ErenE.Gallo16J.Garay GarciaA.GeiserA.GizhkoJ.M.Grados LuyandoA.GrohsjeanP.GunnelliniA.HarbJ.HaukM.Hempel17H.JungA.KalogeropoulosM.KasemannJ.KeaveneyC.KleinwortI.KorolD.KrückerW.LangeA.LelekT.LenzJ.LeonardK.LipkaW.Lohmann17R.MankelI.-A.Melzer-PellmannA.B.MeyerG.MittagJ.MnichA.MussgillerE.NtomariD.PitzlR.PlacakyteA.RasperezaB.RolandM.SavitskyiP.SaxenaR.ShevchenkoS.SpannagelN.StefaniukG.P.Van OnsemR.WalshY.WenK.WichmannC.WissingO.ZenaievDeutsches Elektronen-Synchrotron, Hamburg, GermanyDeutsches Elektronen-SynchrotronHamburgGermany15Also at RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany.16Also at University of Hamburg, Hamburg, Germany.17Also at Brandenburg University of Technology, Cottbus, Germany.S.BeinV.BlobelM.Centis VignaliA.R.DraegerT.DreyerE.GaruttiD.GonzalezJ.HallerM.HoffmannA.JunkesR.KlannerR.KoglerN.KovalchukS.KurzT.LapsienI.MarchesiniD.MarconiM.MeyerM.NiedzielaD.NowatschinF.Pantaleo14T.PeifferA.PerieanuC.ScharfP.SchleperA.SchmidtS.SchumannJ.SchwandtJ.SonneveldH.StadieG.SteinbrückF.M.StoberM.StöverH.TholenD.TroendleE.UsaiL.VanelderenA.VanhoeferB.VormwaldUniversity of Hamburg, Hamburg, GermanyUniversity of HamburgHamburgGermanyM.AkbiyikC.BarthS.BaurC.BausJ.BergerE.ButzR.CaspartT.ChwalekF.ColomboW.De BoerA.DierlammB.FreundR.FrieseM.GiffelsA.GilbertD.HaitzF.Hartmann14S.M.HeindlU.HusemannF.Kassel14S.KudellaH.MildnerM.U.MozerTh.MüllerM.PlaggeG.QuastK.RabbertzM.SchröderI.ShvetsovG.SieberH.J.SimonisR.UlrichS.WayandM.WeberT.WeilerS.WilliamsonC.WöhrmannR.WolfInstitut für Experimentelle Kernphysik, Karlsruhe, GermanyInstitut für Experimentelle KernphysikKarlsruheGermanyG.AnagnostouG.DaskalakisT.GeralisV.A.GiakoumopoulouA.KyriakisD.LoukasI.Topsis-GiotisInstitute of Nuclear and Particle Physics (INPP), NCSR Demokritos, Aghia Paraskevi, GreeceInstitute of Nuclear and Particle Physics (INPP)NCSR DemokritosAghia ParaskeviGreeceS.KesisoglouA.PanagiotouN.SaoulidouNational and Kapodistrian University of Athens, Athens, GreeceNational and Kapodistrian University of AthensAthensGreeceI.EvangelouC.FoudasP.KokkasN.ManthosI.PapadopoulosE.ParadasJ.StrologasF.A.TriantisUniversity of Ioánnina, Ioánnina, GreeceUniversity of IoánninaIoánninaGreeceM.CsanadN.FilipovicG.PasztorMTA-ELTE Lendület CMS Particle and Nuclear Physics Group, Eötvös Loránd University, Budapest, HungaryMTA-ELTE Lendület CMS Particle and Nuclear Physics GroupEötvös Loránd UniversityBudapestHungaryG.BenczeC.HajduD.Horvath18F.SiklerV.VeszpremiG.Vesztergombi19A.J.ZsigmondWigner Research Centre for Physics, Budapest, HungaryWigner Research Centre for PhysicsBudapestHungary18Also at Institute of Nuclear Research ATOMKI, Debrecen, Hungary.19Also at MTA-ELTE Lendület CMS Particle and Nuclear Physics Group, Eötvös Loránd University, Budapest, Hungary.N.BeniS.CzellarJ.Karancsi20A.MakovecJ.MolnarZ.SzillasiInstitute of Nuclear Research ATOMKI, Debrecen, HungaryInstitute of Nuclear Research ATOMKIDebrecenHungary20Also at Institute of Physics, University of Debrecen, Debrecen, Hungary.M.Bartók19P.RaicsZ.L.TrocsanyiB.UjvariInstitute of Physics, University of Debrecen, Debrecen, HungaryInstitute of PhysicsUniversity of DebrecenDebrecenHungaryS.ChoudhuryJ.R.KomaragiriIndian Institute of Science (IISc), Bangalore, IndiaIndian Institute of Science (IISc)BangaloreIndiaS.Bahinipati21S.BhowmikP.MalK.MandalA.Nayak22D.K.Sahoo21N.SahooS.K.SwainNational Institute of Science Education and Research, Bhubaneswar, IndiaNational Institute of Science Education and ResearchBhubaneswarIndia21Also at Indian Institute of Technology Bhubaneswar, Bhubaneswar, India.22Also at Institute of Physics, Bhubaneswar, India.S.BansalS.B.BeriV.BhatnagarU.BhawandeepR.ChawlaN.DhingraA.K.KalsiA.KaurM.KaurR.KumarP.KumariA.MehtaM.MittalJ.B.SinghG.WaliaPanjab University, Chandigarh, IndiaPanjab UniversityChandigarhIndiaAshokKumarAashaqShahA.BhardwajS.ChauhanB.C.ChoudharyR.B.GargS.KeshriA.KumarS.MalhotraM.NaimuddinK.RanjanR.SharmaV.SharmaUniversity of Delhi, Delhi, IndiaUniversity of DelhiDelhiIndiaR.BhardwajR.BhattacharyaS.BhattacharyaS.DeyS.DuttS.DuttaS.GhoshN.MajumdarA.ModakK.MondalS.MukhopadhyayS.NandanA.PurohitA.RoyD.RoyS.Roy ChowdhuryS.SarkarM.SharanS.ThakurSaha Institute of Nuclear Physics, HBNI, Kolkata, IndiaSaha Institute of Nuclear PhysicsHBNIKolkataIndiaP.K.BeheraIndian Institute of Technology Madras, Madras, IndiaIndian Institute of Technology MadrasMadrasIndiaR.ChudasamaD.DuttaV.JhaV.KumarA.K.Mohanty14P.K.NetrakantiL.M.PantP.ShuklaA.TopkarBhabha Atomic Research Centre, Mumbai, IndiaBhabha Atomic Research CentreMumbaiIndiaT.AzizS.DugadB.MahakudS.MitraG.B.MohantyB.ParidaN.SurB.SutarTata Institute of Fundamental Research-A, Mumbai, IndiaTata Institute of Fundamental Research-AMumbaiIndiaS.BanerjeeS.BhattacharyaS.ChatterjeeP.DasM.GuchaitSa.JainS.KumarM.Maity23G.MajumderK.MazumdarT.Sarkar23N.Wickramage24Tata Institute of Fundamental Research-B, Mumbai, IndiaTata Institute of Fundamental Research-BMumbaiIndia23Also at University of Visva-Bharati, Santiniketan, India.24Also at University of Ruhuna, Matara, Sri Lanka.S.ChauhanS.DubeV.HegdeA.KapoorK.KothekarS.PandeyA.RaneS.SharmaIndian Institute of Science Education and Research (IISER), Pune, IndiaIndian Institute of Science Education and Research (IISER)PuneIndiaS.Chenarani25E.Eskandari TadavaniS.M.Etesami25M.KhakzadM.Mohammadi NajafabadiM.NaseriS.Paktinat Mehdiabadi26F.Rezaei HosseinabadiB.Safarzadeh27M.ZeinaliInstitute for Research in Fundamental Sciences (IPM), Tehran, IranInstitute for Research in Fundamental Sciences (IPM)TehranIran25Also at Isfahan University of Technology, Isfahan, Iran.26Also at Yazd University, Yazd, Iran.27Also at Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran.M.FelciniM.GrunewaldUniversity College Dublin, Dublin, IrelandUniversity College DublinDublinIrelandM.AbbresciaabC.CalabriaabC.CaputoabA.ColaleoaD.CreanzaacL.CristellaabN.De FilippisacM.De PalmaabL.FioreaG.IaselliacG.MaggiacM.MaggiaG.MinielloabS.MyabS.NuzzoabA.PompiliabG.PuglieseacR.RadognaabA.RanieriaG.SelvaggiabA.SharmaaL.Silvestrisa14R.VendittiaP.VerwilligenaaINFN Sezione di Bari, Bari, ItalyINFN Sezione di BariBariItalybUniversità di Bari, Bari, ItalyUniversità di BariBariItalycPolitecnico di Bari, Bari, ItalyPolitecnico di BariBariItalyG.AbbiendiaC.BattilanaD.BonacorsiabS.Braibant-GiacomelliabL.BrigliadoriabR.CampaniniabP.CapiluppiabA.CastroabF.R.CavalloaS.S.ChhibraabG.CodispotiabM.CuffianiabG.M.DallavalleaF.FabbriaA.FanfaniabD.FasanellaabP.GiacomelliaL.GuiducciabS.MarcelliniaG.MasettiaF.L.NavarriaabA.PerrottaaA.M.RossiabT.RovelliabG.P.SiroliabN.Tosiab14aINFN Sezione di Bologna, Bologna, ItalyINFN Sezione di BolognaBolognaItalybUniversità di Bologna, Bologna, ItalyUniversità di BolognaBolognaItalyS.AlbergoabS.CostaabA.Di MattiaaF.GiordanoabR.PotenzaabA.TricomiabC.TuveabaINFN Sezione di Catania, Catania, ItalyINFN Sezione di CataniaCataniaItalybUniversità di Catania, Catania, ItalyUniversità di CataniaCataniaItalyG.BarbagliaK.ChatterjeeabV.CiulliabC.CivininiaR.D'AlessandroabE.FocardiabP.LenziabM.MeschiniaS.PaolettiaL.Russoa28G.SguazzoniaD.StromaL.Vilianiab14aINFN Sezione di Firenze, Firenze, ItalyINFN Sezione di FirenzeFirenzeItalybUniversità di Firenze, Firenze, ItalyUniversità di FirenzeFirenzeItaly28Also at Università degli Studi di Siena, Siena, Italy.L.BenussiS.BiancoF.FabbriD.PiccoloF.Primavera14INFN Laboratori Nazionali di Frascati, Frascati, ItalyINFN Laboratori Nazionali di FrascatiFrascatiItalyV.CalvelliabF.FerroaE.RobuttiaS.TosiabaINFN Sezione di Genova, Genova, ItalyINFN Sezione di GenovaGenovaItalybUniversità di Genova, Genova, ItalyUniversità di GenovaGenovaItalyL.BrianzaabF.BrivioabV.CirioloabM.E.DinardoabS.FiorendiabS.GennaiaA.GhezziabP.GovoniabM.MalbertiabS.MalvezziaR.A.ManzoniabD.MenasceaL.MoroniaM.PaganoniabK.PauwelsabD.PedriniaS.Pigazziniab29S.RagazziabT.Tabarelli de FatisabaINFN Sezione di Milano-Bicocca, Milano, ItalyINFN Sezione di Milano-BicoccaMilanoItalybUniversità di Milano-Bicocca, Milano, ItalyUniversità di Milano-BicoccaMilanoItaly29Also at INFN Sezione di Milano-Bicocca; Università di Milano-Bicocca, Milano, Italy.S.BuontempoaN.CavalloacS.Di Guidaad14F.FabozziacF.FiengaabA.O.M.IorioabW.A.KhanaL.ListaaS.Meolaad14P.Paoluccia14C.SciaccaabF.ThyssenaaINFN Sezione di Napoli, Napoli, ItalyINFN Sezione di NapoliNapoliItalybUniversità di Napoli ‘Federico II’, Napoli, ItalyUniversità di Napoli ‘Federico II’NapoliItalycUniversità della Basilicata, Potenza, ItalyUniversità della BasilicataPotenzaItalydUniversità G. Marconi, Roma, ItalyUniversità G. MarconiRomaItalyP.Azzia14N.BacchettaaL.BenatoabA.BolettiabR.CarlinabA.Carvalho Antunes De OliveiraabP.ChecchiaaM.Dall'OssoabP.De Castro ManzanoaT.DorigoaS.FantinelaF.FanzagoaU.GaspariniabF.GonellaaA.GozzelinoaS.LacapraraaM.MargoniabA.T.MeneguzzoabN.PozzobonabP.RoncheseabR.RossinabF.SimonettoabE.TorassaaM.ZanettiabP.ZottoabG.ZumerleabaINFN Sezione di Padova, Padova, ItalyINFN Sezione di PadovaPadovaItalybUniversità di Padova, Padova, ItalyUniversità di PadovaPadovaItalycUniversità di Trento, Trento, ItalyUniversità di TrentoTrentoItalyA.BraghieriaF.FallavollitaabA.MagnaniabP.MontagnaabS.P.RattiabV.ReaM.RessegottiC.RiccardiabP.SalviniaI.VaiabP.VituloabaINFN Sezione di Pavia, Pavia, ItalyINFN Sezione di PaviaPaviaItalybUniversità di Pavia, Pavia, ItalyUniversità di PaviaPaviaItalyL.Alunni SolestiziabG.M.BileiaD.CiangottiniabL.FanòabP.LaricciaabR.LeonardiabG.MantovaniabV.MarianiabM.MenichelliaO.PanellaaA.SahaaA.SantocchiaabD.SpigaaaINFN Sezione di Perugia, Perugia, ItalyINFN Sezione di PerugiaPerugiaItalybUniversità di Perugia, Perugia, ItalyUniversità di PerugiaPerugiaItalyK.AndrosovaP.Azzurria14G.BagliesiaJ.BernardiniaT.BoccaliaL.BorrelloR.CastaldiaM.A.CiocciabR.Dell'OrsoaG.FediaA.GiassiaM.T.Grippoa28F.LigabueacT.LomtadzeaL.MartiniabA.MessineoabF.PallaaA.RizziabA.Savoy-Navarroa30P.SpagnoloaR.TenchiniaG.TonelliabA.VenturiaP.G.VerdiniaaINFN Sezione di Pisa, Pisa, ItalyINFN Sezione di PisaPisaItalybUniversità di Pisa, Pisa, ItalyUniversità di PisaPisaItalycScuola Normale Superiore di Pisa, Pisa, ItalyScuola Normale Superiore di PisaPisaItaly30Also at Purdue University, West Lafayette, USA.L.BaroneabF.CavallariaM.CiprianiabD.Del Reab14M.DiemozaS.GelliabE.LongoabF.MargaroliabB.MarzocchiabP.MeridianiaG.OrgantiniabR.ParamattiabF.PreiatoabS.RahatlouabC.RovelliaF.SantanastasioabaINFN Sezione di Roma, Rome, ItalyINFN Sezione di RomaRomeItalybSapienza Università di Roma, Rome, ItalySapienza Università di RomaRomeItalyN.AmapaneabR.Arcidiaconoac14S.ArgiroabM.ArneodoacN.BartosikaR.BellanabC.BiinoaN.CartigliaaF.CennaabM.CostaabR.CovarelliabA.DeganoabN.DemariaaB.KianiabC.MariottiaS.MaselliaE.MiglioreabV.MonacoabE.MonteilabM.MontenoaM.M.ObertinoabL.PacherabN.PastroneaM.PelliccioniaG.L.Pinna AngioniabF.RaveraabA.RomeroabM.RuspaacR.SacchiabK.ShchelinaabV.SolaaA.SolanoabA.StaianoaP.TraczykabaINFN Sezione di Torino, Torino, ItalyINFN Sezione di TorinoTorinoItalybUniversità di Torino, Torino, ItalyUniversità di TorinoTorinoItalycUniversità del Piemonte Orientale, Novara, ItalyUniversità del Piemonte OrientaleNovaraItalyS.BelforteaM.CasarsaaF.CossuttiaG.Della RiccaabA.ZanettiaaINFN Sezione di Trieste, Trieste, ItalyINFN Sezione di TriesteTriesteItalybUniversità di Trieste, Trieste, ItalyUniversità di TriesteTriesteItalyD.H.KimG.N.KimM.S.KimJ.LeeS.LeeS.W.LeeY.D.OhS.SekmenD.C.SonY.C.YangKyungpook National University, Daegu, Republic of KoreaKyungpook National UniversityDaeguRepublic of KoreaA.LeeChonbuk National University, Jeonju, Republic of KoreaChonbuk National UniversityJeonjuRepublic of KoreaH.KimD.H.MoonG.OhChonnam National University, Institute for Universe and Elementary Particles, Kwangju, Republic of KoreaChonnam National UniversityInstitute for Universe and Elementary ParticlesKwangjuRepublic of KoreaJ.A.Brochero CifuentesJ.GohT.J.KimHanyang University, Seoul, Republic of KoreaHanyang UniversitySeoulRepublic of KoreaS.ChoS.ChoiY.GoD.GyunS.HaB.HongY.JoY.KimK.LeeK.S.LeeS.LeeJ.LimS.K.ParkY.RohKorea University, Seoul, Republic of KoreaKorea UniversitySeoulRepublic of KoreaJ.AlmondJ.KimJ.S.KimH.LeeK.LeeK.NamS.B.OhB.C.Radburn-SmithS.h.SeoU.K.YangH.D.YooG.B.YuSeoul National University, Seoul, Republic of KoreaSeoul National UniversitySeoulRepublic of KoreaM.ChoiH.KimJ.H.KimJ.S.H.LeeI.C.ParkG.RyuUniversity of Seoul, Seoul, Republic of KoreaUniversity of SeoulSeoulRepublic of KoreaY.ChoiC.HwangJ.LeeI.YuSungkyunkwan University, Suwon, Republic of KoreaSungkyunkwan UniversitySuwonRepublic of KoreaV.DudenasA.JuodagalvisJ.VaitkusVilnius University, Vilnius, LithuaniaVilnius UniversityVilniusLithuaniaI.AhmedZ.A.IbrahimM.A.B.Md Ali31F.Mohamad Idris32W.A.T.Wan AbdullahM.N.YusliZ.ZolkapliNational Centre for Particle Physics, Universiti Malaya, Kuala Lumpur, MalaysiaNational Centre for Particle PhysicsUniversiti MalayaKuala LumpurMalaysia31Also at International Islamic University of Malaysia, Kuala Lumpur, Malaysia.32Also at Malaysian Nuclear Agency, MOSTI, Kajang, Malaysia.H.Castilla-ValdezE.De La Cruz-BureloI.Heredia-De La Cruz33R.Lopez-FernandezJ.Mejia GuisaoA.Sanchez-HernandezCentro de Investigacion y de Estudios Avanzados del IPN, Mexico City, MexicoCentro de Investigacion y de Estudios Avanzados del IPNMexico CityMexico33Also at Consejo Nacional de Ciencia y Tecnología, Mexico city, Mexico.S.Carrillo MorenoC.Oropeza BarreraF.Vazquez ValenciaUniversidad Iberoamericana, Mexico City, MexicoUniversidad IberoamericanaMexico CityMexicoI.PedrazaH.A.Salazar IbarguenC.Uribe EstradaBenemerita Universidad Autonoma de Puebla, Puebla, MexicoBenemerita Universidad Autonoma de PueblaPueblaMexicoA.Morelos PinedaUniversidad Autónoma de San Luis Potosí, San Luis Potosí, MexicoUniversidad Autónoma de San Luis PotosíSan Luis PotosíMexicoD.KrofcheckUniversity of Auckland, Auckland, New ZealandUniversity of AucklandAucklandNew ZealandP.H.ButlerUniversity of Canterbury, Christchurch, New ZealandUniversity of CanterburyChristchurchNew ZealandA.AhmadM.AhmadQ.HassanH.R.HooraniA.SaddiqueM.A.ShahM.ShoaibM.WaqasNational Centre for Physics, Quaid-I-Azam University, Islamabad, PakistanNational Centre for PhysicsQuaid-I-Azam UniversityIslamabadPakistanH.BialkowskaM.BlujB.BoimskaT.FrueboesM.GórskiM.KazanaK.NawrockiK.Romanowska-RybinskaM.SzleperP.ZalewskiNational Centre for Nuclear Research, Swierk, PolandNational Centre for Nuclear ResearchSwierkPolandK.BunkowskiA.Byszuk34K.DorobaA.KalinowskiM.KoneckiJ.KrolikowskiM.MisiuraM.OlszewskiA.PyskirM.WalczakInstitute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, PolandInstitute of Experimental PhysicsFaculty of PhysicsUniversity of WarsawWarsawPoland34Also at Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland.P.BargassaC.Beirão Da Cruz E SilvaB.CalpasA.Di FrancescoP.FaccioliM.GallinaroJ.HollarN.LeonardoL.Lloret IglesiasM.V.NemallapudiJ.SeixasO.ToldaievD.VadruccioJ.VarelaLaboratório de Instrumentação e Física Experimental de Partículas, Lisboa, PortugalLaboratório de Instrumentação e Física Experimental de PartículasLisboaPortugalS.AfanasievP.BuninM.GavrilenkoI.GolutvinI.GorbunovA.KamenevV.KarjavinA.LanevA.MalakhovV.Matveev3536V.PalichikV.PerelyginS.ShmatovS.ShulhaN.SkatchkovV.SmirnovN.VoytishinA.ZarubinJoint Institute for Nuclear Research, Dubna, RussiaJoint Institute for Nuclear ResearchDubnaRussia35Also at Institute for Nuclear Research, Moscow, Russia.36Now at National Research Nuclear University ‘Moscow Engineering Physics Institute’ (MEPhI), Moscow, Russia.Y.IvanovV.Kim37E.Kuznetsova38P.LevchenkoV.MurzinV.OreshkinI.SmirnovV.SulimovL.UvarovS.VavilovA.VorobyevPetersburg Nuclear Physics Institute, Gatchina (St. Petersburg), RussiaPetersburg Nuclear Physics InstituteGatchina (St. Petersburg)Russia37Also at St. Petersburg State Polytechnical University, St. Petersburg, Russia.38Also at University of Florida, Gainesville, USA.Yu.AndreevA.DermenevS.GninenkoN.GolubevA.KarneyeuM.KirsanovN.KrasnikovA.PashenkovD.TlisovA.ToropinInstitute for Nuclear Research, Moscow, RussiaInstitute for Nuclear ResearchMoscowRussiaV.EpshteynV.GavrilovN.LychkovskayaV.PopovI.PozdnyakovG.SafronovA.SpiridonovA.StepennovM.TomsE.VlasovA.ZhokinInstitute for Theoretical and Experimental Physics, Moscow, RussiaInstitute for Theoretical and Experimental PhysicsMoscowRussiaT.AushevA.Bylinkin36Moscow Institute of Physics and Technology, Moscow, RussiaMoscow Institute of Physics and TechnologyMoscowRussiaP.ParyginD.PhilippovV.RusinovNational Research Nuclear University, ‘Moscow Engineering Physics Institute’ (MEPhI), Moscow, RussiaNational Research Nuclear University‘Moscow Engineering Physics Institute’ (MEPhI)MoscowRussiaV.AndreevM.Azarkin36I.Dremin36M.KirakosyanA.TerkulovP.N. Lebedev Physical Institute, Moscow, RussiaP.N. Lebedev Physical InstituteMoscowRussiaA.BaskakovA.BelyaevE.BoosM.Dubinin39L.DudkoA.ErshovA.GribushinV.KlyukhinO.KodolovaI.LokhtinI.MiagkovS.ObraztsovS.PetrushankoV.SavrinA.SnigirevSkobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, RussiaSkobeltsyn Institute of Nuclear PhysicsLomonosov Moscow State UniversityMoscowRussia39Also at California Institute of Technology, Pasadena, USA.V.Blinov40Y.Skovpen40D.Shtol40Novosibirsk State University (NSU), Novosibirsk, RussiaNovosibirsk State University (NSU)NovosibirskRussia40Also at Budker Institute of Nuclear Physics, Novosibirsk, Russia.I.AzhgireyI.BayshevS.BitioukovD.ElumakhovV.KachanovA.KalininD.KonstantinovV.KrychkineV.PetrovR.RyutinA.SobolS.TroshinN.TyurinA.UzunianA.VolkovState Research Center of Russian Federation, Institute for High Energy Physics, Protvino, RussiaState Research Center of Russian FederationInstitute for High Energy PhysicsProtvinoRussiaP.Adzic41P.CirkovicD.DevetakM.DordevicJ.MilosevicV.RekovicUniversity of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, SerbiaUniversity of BelgradeFaculty of PhysicsVinca Institute of Nuclear SciencesBelgradeSerbia41Also at Faculty of Physics, University of Belgrade, Belgrade, Serbia.J.Alcaraz MaestreM.Barrio LunaM.CerradaN.ColinoB.De La CruzA.Delgado PerisA.Escalante Del ValleC.Fernandez BedoyaJ.P.Fernández RamosJ.FlixM.C.FouzP.Garcia-AbiaO.Gonzalez LopezS.Goy LopezJ.M.HernandezM.I.JosaA.Pérez-Calero YzquierdoJ.Puerta PelayoA.Quintario OlmedaI.RedondoL.RomeroM.S.SoaresA.Álvarez FernándezCentro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, SpainCentro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT)MadridSpainJ.F.de TrocónizM.MissiroliD.MoranUniversidad Autónoma de Madrid, Madrid, SpainUniversidad Autónoma de MadridMadridSpainJ.CuevasC.EriceJ.Fernandez MenendezI.Gonzalez CaballeroJ.R.González FernándezE.Palencia CortezonS.Sanchez CruzI.Suárez AndrésP.VischiaJ.M.Vizan GarciaUniversidad de Oviedo, Oviedo, SpainUniversidad de OviedoOviedoSpainI.J.CabrilloA.CalderonB.Chazin QueroE.CurrasM.FernandezJ.Garcia-FerreroG.GomezA.Lopez VirtoJ.MarcoC.Martinez RiveroP.Martinez Ruiz del ArbolF.MatorrasJ.Piedra GomezT.RodrigoA.Ruiz-JimenoL.ScodellaroN.TrevisaniI.VilaR.Vilar CortabitarteInstituto de Física de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, SpainInstituto de Física de Cantabria (IFCA)CSIC-Universidad de CantabriaSantanderSpainD.AbbaneoE.AuffrayP.BaillonA.H.BallD.BarneyM.BiancoP.BlochA.BocciC.BottaT.CamporesiR.CastelloM.CepedaG.CerminaraE.ChaponY.ChenD.d'EnterriaA.DabrowskiV.DaponteA.DavidM.De GruttolaA.De RoeckE.Di Marco42M.DobsonB.DorneyT.du PreeM.DünserN.DupontA.Elliott-PeisertP.EveraertsG.FranzoniJ.FulcherW.FunkD.GigiK.GillF.GlegeD.GulhanS.GundackerM.GuthoffP.HarrisJ.HegemanV.InnocenteP.JanotO.Karacheban17J.KieselerH.KirschenmannV.KnünzA.Kornmayer14M.J.KortelainenC.LangeP.LecoqC.LourençoM.T.LucchiniL.MalgeriM.MannelliA.MartelliF.MeijersJ.A.MerlinS.MersiE.MeschiP.Milenovic43F.MoortgatM.MuldersH.NeugebauerS.OrfanelliL.OrsiniL.PapeE.PerezM.PeruzziA.PetrilliG.PetruccianiA.PfeifferM.PieriniA.RaczT.ReisG.Rolandi44M.RovereH.SakulinJ.B.SauvanC.SchäferC.SchwickM.SeidelM.SelvaggiA.SharmaP.SilvaP.Sphicas45J.SteggemannM.StoyeM.TosiD.TreilleA.TriossiA.TsirouV.Veckalns46G.I.Veres19M.VerweijN.WardleW.D.ZeunerCERN, European Organization for Nuclear Research, Geneva, SwitzerlandCERNEuropean Organization for Nuclear ResearchGenevaSwitzerland42Also at INFN Sezione di Roma; Sapienza Università di Roma, Rome, Italy.43Also at University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia.44Also at Scuola Normale e Sezione dell'INFN, Pisa, Italy.45Also at National and Kapodistrian University of Athens, Athens, Greece.46Also at Riga Technical University, Riga, Latvia.W.Bertl†K.DeitersW.ErdmannR.HorisbergerQ.IngramH.C.KaestliD.KotlinskiU.LangeneggerT.RoheS.A.WiederkehrPaul Scherrer Institut, Villigen, SwitzerlandPaul Scherrer InstitutVilligenSwitzerland†Deceased.F.BachmairL.BäniP.BergerL.BianchiniB.CasalG.DissertoriM.DittmarM.DonegàC.GrabC.HeideggerD.HitsJ.HossG.KasieczkaT.KlijnsmaW.LustermannB.ManganoM.MarionneauM.T.MeinhardD.MeisterF.MicheliP.MusellaF.Nessi-TedaldiF.PandolfiJ.PataF.PaussG.PerrinL.PerrozziM.QuittnatM.RossiniM.SchönenbergerL.ShchutskaA.Starodumov47V.R.TavolaroK.TheofilatosM.L.Vesterbacka OlssonR.WallnyA.Zagozdzinska34D.H.ZhuInstitute for Particle Physics, ETH Zurich, Zurich, SwitzerlandInstitute for Particle PhysicsETH ZurichZurichSwitzerland47Also at Institute for Theoretical and Experimental Physics, Moscow, Russia.T.K.AarrestadC.Amsler48L.CaminadaM.F.CanelliA.De CosaS.DonatoC.GalloniA.HinzmannT.HreusB.KilminsterJ.NgadiubaD.PinnaG.RaucoP.RobmannD.SalernoC.SeitzA.ZucchettaUniversität Zürich, Zurich, SwitzerlandUniversität ZürichZurichSwitzerland48Also at Albert Einstein Center for Fundamental Physics, Bern, Switzerland.V.CandeliseT.H.DoanSh.JainR.KhuranaM.KonyushikhinC.M.KuoW.LinA.PozdnyakovS.S.YuNational Central University, Chung-Li, TaiwanNational Central UniversityChung-LiTaiwanArunKumarP.ChangY.ChaoK.F.ChenP.H.ChenF.FioriW.-S.HouY.HsiungY.F.LiuR.-S.LuM.Miñano MoyaE.PaganisA.PsallidasJ.f.TsaiNational Taiwan University (NTU), Taipei, TaiwanNational Taiwan University (NTU)TaipeiTaiwanB.AsavapibhopK.KovitanggoonG.SinghN.SrimanobhasChulalongkorn University, Faculty of Science, Department of Physics, Bangkok, ThailandChulalongkorn UniversityFaculty of ScienceDepartment of PhysicsBangkokThailandA.Adiguzel49M.N.Bakirci50F.BoranS.Cerci51S.DamarseckinZ.S.DemirogluC.DozenI.DumanogluS.GirgisG.GokbulutY.GulerI.Hos52E.E.Kangal53O.KaraA.Kayis TopaksuU.KiminsuM.OglakciG.Onengut54K.Ozdemir55B.Tali51S.TurkcaparI.S.ZorbakirC.ZorbilmezÇukurova University, Physics Department, Science and Art Faculty, Adana, TurkeyÇukurova UniversityPhysics DepartmentScience and Art FacultyAdanaTurkey49Also at Istanbul University, Faculty of Science, Istanbul, Turkey.50Also at Gaziosmanpasa University, Tokat, Turkey.51Also at Adiyaman University, Adiyaman, Turkey.52Also at Istanbul Aydin University, Istanbul, Turkey.53Also at Mersin University, Mersin, Turkey.54Also at Cag University, Mersin, Turkey.55Also at Piri Reis University, Istanbul, Turkey.B.BilinG.Karapinar56K.Ocalan57M.YalvacM.ZeyrekMiddle East Technical University, Physics Department, Ankara, TurkeyMiddle East Technical UniversityPhysics DepartmentAnkaraTurkey56Also at Izmir Institute of Technology, Izmir, Turkey.57Also at Necmettin Erbakan University, Konya, Turkey.E.GülmezM.Kaya58O.Kaya59S.TektenE.A.Yetkin60Bogazici University, Istanbul, TurkeyBogazici UniversityIstanbulTurkey58Also at Marmara University, Istanbul, Turkey.59Also at Kafkas University, Kars, Turkey.60Also at Istanbul Bilgi University, Istanbul, Turkey.M.N.AgarasS.AtayA.CakirK.CankocakIstanbul Technical University, Istanbul, TurkeyIstanbul Technical UniversityIstanbulTurkeyB.GrynyovInstitute for Scintillation Materials of National Academy of Science of Ukraine, Kharkov, UkraineInstitute for Scintillation Materials of National Academy of Science of UkraineKharkovUkraineL.LevchukP.SorokinNational Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, UkraineNational Scientific CenterKharkov Institute of Physics and TechnologyKharkovUkraineR.AggletonF.BallL.BeckJ.J.BrookeD.BurnsE.ClementD.CussansH.FlacherJ.GoldsteinM.GrimesG.P.HeathH.F.HeathJ.JacobL.KreczkoC.LucasD.M.Newbold61S.ParamesvaranA.PollT.SakumaS.Seif El Nasr-storeyD.SmithV.J.SmithUniversity of Bristol, Bristol, United KingdomUniversity of BristolBristolUnited Kingdom61Also at Rutherford Appleton Laboratory, Didcot, United Kingdom.K.W.BellA.Belyaev62C.BrewR.M.BrownL.CalligarisD.CieriD.J.A.CockerillJ.A.CoughlanK.HarderS.HarperE.OlaiyaD.PetytC.H.Shepherd-ThemistocleousA.TheaI.R.TomalinT.WilliamsRutherford Appleton Laboratory, Didcot, United KingdomRutherford Appleton LaboratoryDidcotUnited Kingdom62Also at School of Physics and Astronomy, University of Southampton, Southampton, United Kingdom.M.BaberR.BainbridgeS.BreezeO.BuchmullerA.BundockS.CasassoM.CitronD.CollingL.CorpeP.DaunceyG.DaviesA.De WitM.Della NegraR.Di MariaP.DunneA.ElwoodD.FutyanY.HaddadG.HallG.IlesT.JamesR.LaneC.LanerL.LyonsA.-M.MagnanS.MalikL.MastrolorenzoT.MatsushitaJ.NashA.Nikitenko47J.PelaM.PesaresiD.M.RaymondA.RichardsA.RoseE.ScottC.SeezA.ShtipliyskiS.SummersA.TapperK.UchidaM.Vazquez Acosta63T.Virdee14D.WinterbottomJ.WrightS.C.ZenzImperial College, London, United KingdomImperial CollegeLondonUnited Kingdom63Also at Instituto de Astrofísica de Canarias, La Laguna, Spain.J.E.ColeP.R.HobsonA.KhanP.KyberdI.D.ReidP.SymondsL.TeodorescuM.TurnerBrunel University, Uxbridge, United KingdomBrunel UniversityUxbridgeUnited KingdomA.BorzouK.CallJ.DittmannK.HatakeyamaH.LiuN.PastikaBaylor University, Waco, USABaylor UniversityWacoUSAR.BartekA.DominguezCatholic University of America, Washington DC, USACatholic University of AmericaWashingtonDCUSAA.BuccilliS.I.CooperC.HendersonP.RumerioC.WestThe University of Alabama, Tuscaloosa, USAThe University of AlabamaTuscaloosaUSAD.ArcaroA.AvetisyanT.BoseD.GastlerD.RankinC.RichardsonJ.RohlfL.SulakD.ZouBoston University, Boston, USABoston UniversityBostonUSAG.BenelliD.CuttsA.GarabedianJ.HakalaU.HeintzJ.M.HoganK.H.M.KwokE.LairdG.LandsbergZ.MaoM.NarainS.PiperovS.SagirR.SyarifD.YuBrown University, Providence, USABrown UniversityProvidenceUSAR.BandC.BrainerdD.BurnsM.Calderon De La Barca SanchezM.ChertokJ.ConwayR.ConwayP.T.CoxR.ErbacherC.FloresG.FunkM.GardnerW.KoR.LanderC.McleanM.MulhearnD.PellettJ.PilotS.ShalhoutM.ShiJ.SmithM.SquiresD.StolpK.TosM.TripathiZ.WangUniversity of California, Davis, Davis, USAUniversity of California, DavisDavisUSAM.BachtisC.BravoR.CousinsA.DasguptaA.FlorentJ.HauserM.IgnatenkoN.MccollD.SaltzbergC.SchnaibleV.ValuevUniversity of California, Los Angeles, USAUniversity of CaliforniaLos AngelesUSAE.BouvierK.BurtR.ClareJ.EllisonJ.W.GaryS.M.A.Ghiasi ShiraziG.HansonJ.HeilmanP.JandirE.KennedyF.LacroixO.R.LongM.Olmedo NegreteM.I.PanevaA.ShrinivasW.SiH.WeiS.WimpennyB.R.YatesUniversity of California, Riverside, Riverside, USAUniversity of California, RiversideRiversideUSAJ.G.BransonG.B.CeratiS.CittolinM.DerdzinskiB.HashemiA.HolznerD.KleinG.KoleV.KrutelyovJ.LettsI.MacneillM.MasciovecchioD.OlivitoS.PadhiM.PieriM.SaniV.SharmaS.SimonM.TadelA.VartakS.Wasserbaech64J.WoodF.WürthweinA.YagilG.Zevi Della PortaUniversity of California, San Diego, La Jolla, USAUniversity of California, San DiegoLa JollaUSA64Also at Utah Valley University, Orem, USA.N.AminR.BhandariJ.Bradmiller-FeldC.CampagnariA.DishawV.DuttaM.Franco SevillaC.GeorgeF.GolfL.GouskosJ.GranR.HellerJ.IncandelaS.D.MullinA.OvcharovaH.QuJ.RichmanD.StuartI.SuarezJ.YooUniversity of California, Santa Barbara – Department of Physics, Santa Barbara, USAUniversity of California, Santa BarbaraDepartment of PhysicsSanta BarbaraUSAD.AndersonJ.BendavidA.BornheimJ.M.LawhornH.B.NewmanT.NguyenC.PenaM.SpiropuluJ.R.VlimantS.XieZ.ZhangR.Y.ZhuCalifornia Institute of Technology, Pasadena, USACalifornia Institute of TechnologyPasadenaUSAM.B.AndrewsT.FergusonT.MudholkarM.PauliniJ.RussM.SunH.VogelI.VorobievM.WeinbergCarnegie Mellon University, Pittsburgh, USACarnegie Mellon UniversityPittsburghUSAJ.P.CumalatW.T.FordF.JensenA.JohnsonM.KrohnS.LeontsinisT.MulhollandK.StensonS.R.WagnerUniversity of Colorado Boulder, Boulder, USAUniversity of Colorado BoulderBoulderUSAJ.AlexanderJ.ChavesJ.ChuS.DittmerK.McdermottN.MirmanJ.R.PattersonA.RinkeviciusA.RydL.SkinnariL.SoffiS.M.TanZ.TaoJ.ThomJ.TuckerP.WittichM.ZientekCornell University, Ithaca, USACornell UniversityIthacaUSAS.AbdullinM.AlbrowG.ApollinariA.ApresyanA.ApyanS.BanerjeeL.A.T.BauerdickA.BeretvasJ.BerryhillP.C.BhatG.BollaK.BurkettJ.N.ButlerA.CanepaH.W.K.CheungF.ChlebanaM.CremonesiJ.DuarteV.D.ElviraJ.FreemanZ.GecseE.GottschalkL.GrayD.GreenS.GrünendahlO.GutscheR.M.HarrisS.HasegawaJ.HirschauerZ.HuB.JayatilakaS.JindarianiM.JohnsonU.JoshiB.KlimaB.KreisS.LammelD.LincolnR.LiptonM.LiuT.LiuR.Lopes De SáJ.LykkenK.MaeshimaN.MaginiJ.M.MarraffinoS.MaruyamaD.MasonP.McBrideP.MerkelS.MrennaS.NahnV.O'DellK.PedroO.ProkofyevG.RaknessL.RistoriB.SchneiderE.Sexton-KennedyA.SohaW.J.SpaldingL.SpiegelS.StoynevJ.StraitN.StrobbeL.TaylorS.TkaczykN.V.TranL.UpleggerE.W.VaanderingC.VernieriM.VerzocchiR.VidalM.WangH.A.WeberA.WhitbeckFermi National Accelerator Laboratory, Batavia, USAFermi National Accelerator LaboratoryBataviaUSAD.AcostaP.AveryP.BortignonA.BrinkerhoffA.CarnesM.CarverD.CurryS.DasR.D.FieldI.K.FuricJ.KonigsbergA.KorytovK.KotovP.MaK.MatchevH.MeiG.MitselmakherD.RankD.SperkaN.TerentyevL.ThomasJ.WangS.WangJ.YeltonUniversity of Florida, Gainesville, USAUniversity of FloridaGainesvilleUSAY.R.JoshiS.LinnP.MarkowitzG.MartinezJ.L.RodriguezFlorida International University, Miami, USAFlorida International UniversityMiamiUSAA.AckertT.AdamsA.AskewS.HagopianV.HagopianK.F.JohnsonT.KolbergT.PerryH.ProsperA.SantraR.YohayFlorida State University, Tallahassee, USAFlorida State UniversityTallahasseeUSAM.M.BaarmandV.BhopatkarS.ColafranceschiM.HohlmannD.NoonanT.RoyF.YumicevaFlorida Institute of Technology, Melbourne, USAFlorida Institute of TechnologyMelbourneUSAM.R.AdamsL.ApanasevichD.BerryR.R.BettsR.CavanaughX.ChenO.EvdokimovC.E.GerberD.A.HangalD.J.HofmanK.JungJ.KaminI.D.Sandoval GonzalezM.B.TonjesH.TraugerN.VarelasH.WangZ.WuJ.ZhangUniversity of Illinois at Chicago (UIC), Chicago, USAUniversity of Illinois at Chicago (UIC)ChicagoUSAB.Bilki65W.ClaridaK.Dilsiz66S.DurgutR.P.GandrajulaM.HaytmyradovV.KhristenkoJ.-P.MerloH.Mermerkaya67A.MestvirishviliA.MoellerJ.NachtmanH.Ogul68Y.OnelF.Ozok69A.PenzoC.SnyderE.TirasJ.WetzelK.YiThe University of Iowa, Iowa City, USAThe University of IowaIowa CityUSA65Also at Beykent University, Istanbul, Turkey.66Also at Bingol University, Bingol, Turkey.67Also at Erzincan University, Erzincan, Turkey.68Also at Sinop University, Sinop, Turkey.69Also at Mimar Sinan University, Istanbul, Istanbul, Turkey.B.BlumenfeldA.CocorosN.EminizerD.FehlingL.FengA.V.GritsanP.MaksimovicJ.RoskesU.SaricaM.SwartzM.XiaoC.YouJohns Hopkins University, Baltimore, USAJohns Hopkins UniversityBaltimoreUSAA.Al-batainehP.BaringerA.BeanS.BorenJ.BowenJ.CastleS.KhalilA.KropivnitskayaD.MajumderW.McbrayerM.MurrayC.RoyonS.SandersE.SchmitzR.StringerJ.D.Tapia TakakiQ.WangThe University of Kansas, Lawrence, USAThe University of KansasLawrenceUSAA.IvanovK.KaadzeY.MaravinA.MohammadiL.K.SainiN.SkhirtladzeS.TodaKansas State University, Manhattan, USAKansas State UniversityManhattanUSAF.RebassooD.WrightLawrence Livermore National Laboratory, Livermore, USALawrence Livermore National LaboratoryLivermoreUSAC.AnelliA.BadenO.BaronA.BelloniB.CalvertS.C.EnoC.FerraioliN.J.HadleyS.JabeenG.Y.JengR.G.KelloggJ.KunkleA.C.MignereyF.Ricci-TamY.H.ShinA.SkujaS.C.TonwarUniversity of Maryland, College Park, USAUniversity of MarylandCollege ParkUSAD.AbercrombieB.AllenV.AzzoliniR.BarbieriA.BatyR.BiS.BrandtW.BuszaI.A.CaliM.D'AlfonsoZ.DemiragliG.Gomez CeballosM.GoncharovD.HsuY.IiyamaG.M.InnocentiM.KluteD.KovalskyiY.S.LaiY.-J.LeeA.LevinP.D.LuckeyB.MaierA.C.MariniC.McginnC.MironovS.NarayananX.NiuC.PausC.RolandG.RolandJ.Salfeld-NebgenG.S.F.StephansK.TatarD.VelicanuJ.WangT.W.WangB.WyslouchMassachusetts Institute of Technology, Cambridge, USAMassachusetts Institute of TechnologyCambridgeUSAA.C.BenvenutiR.M.ChatterjeeA.EvansP.HansenS.KalafutS.C.KaoY.KubotaZ.LeskoJ.MansS.NourbakhshN.RuckstuhlR.RusackN.TambeJ.TurkewitzUniversity of Minnesota, Minneapolis, USAUniversity of MinnesotaMinneapolisUSAJ.G.AcostaS.OliverosUniversity of Mississippi, Oxford, USAUniversity of MississippiOxfordUSAE.AvdeevaK.BloomD.R.ClaesC.FangmeierR.Gonzalez SuarezR.KamalieddinI.KravchenkoJ.MonroyJ.E.SiadoG.R.SnowB.StiegerUniversity of Nebraska—Lincoln, Lincoln, USAUniversity of Nebraska—LincolnLincolnUSAM.AlyariJ.DolenA.GodshalkC.HarringtonI.IashviliD.NguyenA.ParkerS.RappoccioB.RoozbahaniState University of New York at Buffalo, Buffalo, USAState University of New York at BuffaloBuffaloUSAG.AlversonE.BarberisA.HortiangthamA.MassironiD.M.MorseD.NashT.OrimotoR.Teixeira De LimaD.TrocinoR.-J.WangD.WoodNortheastern University, Boston, USANortheastern UniversityBostonUSAS.BhattacharyaO.CharafK.A.HahnN.MuciaN.OdellB.PollackM.H.SchmittK.SungM.TrovatoM.VelascoNorthwestern University, Evanston, USANorthwestern UniversityEvanstonUSAN.DevM.HildrethK.Hurtado AnampaC.JessopD.J.KarmgardN.KellamsK.LannonN.LoukasN.MarinelliF.MengC.MuellerY.Musienko35M.PlanerA.ReinsvoldR.RuchtiG.SmithS.TaroniM.WayneM.WolfA.WoodardUniversity of Notre Dame, Notre Dame, USAUniversity of Notre DameNotre DameUSAJ.AlimenaL.AntonelliB.BylsmaL.S.DurkinS.FlowersB.FrancisA.HartC.HillW.JiB.LiuW.LuoD.PuighB.L.WinerH.W.WulsinThe Ohio State University, Columbus, USAThe Ohio State UniversityColumbusUSAA.BenagliaS.CoopersteinO.DrigaP.ElmerJ.HardenbrookP.HebdaD.LangeJ.LuoD.MarlowK.MeiI.OjalvoJ.OlsenC.PalmerP.PirouéD.SticklandA.SvyatkovskiyC.TullyPrinceton University, Princeton, USAPrinceton UniversityPrincetonUSAS.MalikS.NorbergUniversity of Puerto Rico, Mayaguez, USAUniversity of Puerto RicoMayaguezUSAA.BarkerV.E.BarnesS.FolguerasL.GutayM.K.JhaM.JonesA.W.JungA.KhatiwadaD.H.MillerN.NeumeisterJ.F.SchulteJ.SunF.WangW.XiePurdue University, West Lafayette, USAPurdue UniversityWest LafayetteUSAT.ChengN.ParasharJ.StupakPurdue University Northwest, Hammond, USAPurdue University NorthwestHammondUSAA.AdairB.AkgunZ.ChenK.M.EcklundF.J.M.GeurtsM.GuilbaudW.LiB.MichlinM.NorthupB.P.PadleyJ.RobertsJ.RorieZ.TuJ.ZabelRice University, Houston, USARice UniversityHoustonUSAA.BodekP.de BarbaroR.DeminaY.t.DuhT.FerbelM.GalantiA.Garcia-BellidoJ.HanO.HindrichsA.KhukhunaishviliK.H.LoP.TanM.VerzettiUniversity of Rochester, Rochester, USAUniversity of RochesterRochesterUSAR.CiesielskiK.GoulianosC.MesropianThe Rockefeller University, New York, USAThe Rockefeller UniversityNew YorkUSAA.AgapitosJ.P.ChouY.GershteinT.A.Gómez EspinosaE.HalkiadakisM.HeindlE.HughesS.KaplanR.Kunnawalkam ElayavalliS.KyriacouA.LathR.MontalvoK.NashM.OshersonH.SakaS.SalurS.SchnetzerD.SheffieldS.SomalwarR.StoneS.ThomasP.ThomassenM.WalkerRutgers, The State University of New Jersey, Piscataway, USARutgers, The State University of New JerseyPiscatawayUSAM.FoersterJ.HeidemanG.RileyK.RoseS.SpanierK.ThapaUniversity of Tennessee, Knoxville, USAUniversity of TennesseeKnoxvilleUSAO.Bouhali70A.Castaneda Hernandez70A.CelikM.DalchenkoM.De MattiaA.DelgadoS.DildickR.EusebiJ.GilmoreT.HuangT.Kamon71R.MuellerY.PakhotinR.PatelA.PerloffL.PernièD.RathjensA.SafonovA.TatarinovK.A.UlmerTexas A&M University, College Station, USATexas A&M UniversityCollege StationUSA70Also at Texas A&M University at Qatar, Doha, Qatar.71Also at Kyungpook National University, Daegu, Republic of Korea.N.AkchurinJ.DamgovF.De GuioP.R.DuderoJ.FaulknerE.GurpinarS.KunoriK.LamichhaneS.W.LeeT.LibeiroT.PeltolaS.UndleebI.VolobouevZ.WangTexas Tech University, Lubbock, USATexas Tech UniversityLubbockUSAS.GreeneA.GurrolaR.JanjamW.JohnsC.MaguireA.MeloH.NiP.SheldonS.TuoJ.VelkovskaQ.XuVanderbilt University, Nashville, USAVanderbilt UniversityNashvilleUSAM.W.ArentonP.BarriaB.CoxR.HiroskyA.LedovskoyH.LiC.NeuT.SinthuprasithX.SunY.WangE.WolfeF.XiaUniversity of Virginia, Charlottesville, USAUniversity of VirginiaCharlottesvilleUSAC.ClarkeR.HarrP.E.KarchinJ.SturdyS.ZaleskiWayne State University, Detroit, USAWayne State UniversityDetroitUSAD.A.BelknapJ.BuchananC.CaillolS.DasuL.DoddS.DuricB.GomberM.GrotheM.HerndonA.HervéU.HussainP.KlabbersA.LanaroA.LevineK.LongR.LovelessG.A.PierroG.PoleseT.RugglesA.SavinN.SmithW.H.SmithD.TaylorN.WoodsUniversity of Wisconsin – Madison, Madison, WI, USAUniversity of Wisconsin – MadisonMadisonWIUSACERN, SwitzerlandCERNSwitzerland⋆E-mail address: cms-publication-committee-chair@cern.ch.Editor: M. DoserAbstractA search for physics beyond the standard model in the final state with two same-flavour leptons (electrons or muons) and two quarks produced in proton–proton collisions at s=13TeV is presented. The data were recorded by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 2.3fb−1. The observed data are in good agreement with the standard model background prediction. The results of the measurement are interpreted in the framework of a recently proposed model in which a heavy Majorana neutrino, Nℓ, stems from a composite-fermion scenario. Exclusion limits are set for the first time on the mass of the heavy composite Majorana neutrino, mNℓ, and the compositeness scale Λ. For the case mNℓ=Λ, the existence of Ne (Nμ) is excluded for masses up to 4.60 (4.70) TeV at 95% confidence level.KeywordsCMSExotica1IntroductionExperimental evidence has promoted the standard model (SM) to the role of the reference theory for high-energy particle physics. Despite its successes, there are several fundamental aspects of observed particle physics that lack a complete explanation within the SM. One of these is the mass hierarchy of fermions, for which a possible solution has been offered by composite-fermion models [1–3].In the composite-fermion scenario, quarks and leptons are assumed to have an internal substructure that should manifest itself at some sufficiently high energy scale, the compositeness scale Λ. Ordinary fermions are considered as bound states of some not yet observed fundamental constituents generically referred to as preons. Two model-independent properties [4–7] are experimentally relevant: the existence of a contact interaction, in addition to the gauge interaction, which represents an effective approach for describing the effects of the unknown internal dynamics of compositeness, and the existence of excited states of quarks and leptons with masses lower than or equal to Λ. A particular case of such excited states could be a heavy composite Majorana neutrino (HCMN), Nℓ (ℓ=e,μ,τ) [8–11].In this Letter we present, for the first time, the results of a search for heavy composite Majorana neutrinos predicted in the framework of a new model described in Ref. [12]. In that reference, the production and decay of Nℓ are analyzed, considering both gauge and contact interactions. The total interaction is given by the coherent sum of the contact and the gauge contributions, as shown in Fig. 1. The contribution of the contact interaction to the production cross section is two to three orders of magnitude higher compared to that of the gauge interaction [12].The contact interaction is described by an effective four-fermion Lagrangian of the type(1)LC=g⁎2Λ212jμjμ, with(2)jμ=ηLafL¯γμfL′+ηLbfL⁎¯γμfL⁎′+ηLcfL⁎¯γμfL′+h.c.+(L→R), where fL and fL⁎ are the SM and excited left-handed fermion fields, g⁎2=4π, and the η factors, which define the chiral structure, are set equal to one. The gauge interaction between the SM fermions and the excited fermions is described by a magnetic-type coupling(3)LG=12ΛLR⁎‾σμν(gfτ→2⋅W→μν+g′f′YBμν)LL+h.c. where LR⁎ and LL are the right-handed excited doublet and left-handed SM doublet, g and g′ are the SU(2)L and U(1)Y gauge couplings, W→μν and Bμν are the field strengths for the SU(2)L and U(1)Y gauge fields, respectively, τ→ are the Pauli matrices, Y is the weak hypercharge, and f and f′ are dimensionless couplings, assumed to be 1 [7].From the Lagrangians in Eqs. (1) and (3) we can infer that the higher the value of Λ, the lower the production cross section of the heavy composite Majorana neutrino. Since Nℓ is its own antiparticle, it can be produced either as a neutrino or an antineutrino. In pp collisions it can be produced in association with a lepton through quark–antiquark annihilation (qq‾′→ℓ+Nℓ). This process can occur via both gauge and contact interactions. The latter is dominant for a wide range of Λ values, including the ones to which we are sensitive in this search. Fig. 2 (top) shows the leading order (LO) production cross section, as a function of the Nℓ mass, for the case Λ=9 TeV, which is one of the values considered in this Letter whose calculation is based on Ref. [12].The heavy composite Majorana neutrino can decay through both gauge and contact interactions. In this case, either the gauge or the contact interaction is dominant, depending on Λ and on the mass of Nℓ, as illustrated in Fig. 2 (bottom).Being a Majorana particle, Nℓ can decay either as a neutrino or an antineutrino with possible decay modes:Nℓ→ℓqq‾′,Nℓ→ℓ+ℓ−νℓ(ν‾ℓ),Nℓ→νℓ(νℓ‾)qq‾′, where the parentheses indicate that the decay product can be a neutrino or an antineutrino. The possible final states are:ℓℓqq‾′,ℓℓℓνℓ(νℓ‾),ℓνℓ(νℓ‾)qq‾′.In this Letter, the final state ℓℓqq‾′ is considered, as it has the highest sensitivity. We focus on the cases in which ℓ is either an electron or a muon, giving rise to the channels eeqq‾′ and μμqq‾′.For our analysis we use a data sample of proton–proton collisions at s=13TeV recorded in 2015 with the CMS detector at the CERN LHC, which corresponds to an integrated luminosity of 2.3fb−1 [13].Previous searches for compositeness models have been carried out at pp, pp‾, e+e−, and ep colliders. The most recent results, from the ATLAS and CMS Collaborations, are given in [14,15] and exclude the existence of excited electrons (muons) up to masses of 2.45 (2.47) TeV at 95% confidence level (CL), for the case mℓ⁎=Λ. The search performed in the context of Ref. [12], which is discussed below, can reach a sensitivity for the existence of heavy composite Majorana neutrinos up to masses of 4.55 (4.77) TeV for Ne (Nμ), for the case mℓ⁎=Λ.Direct searches for heavy neutrinos have been performed by the ATLAS [16,17] and CMS [18–21] Collaborations. These previous searches have been performed in the ℓℓqq‾′ (ℓ=e,μ,τ) channels, considering two leptons and two spatially separated jets. However, in our case, this selection has limited acceptance for gauge boson mediated decays, for which the two jets are expected to overlap, as they originate from highly Lorentz-boosted hadronic W boson decay products. We overcome this constraint by selecting events with at least one jet with angular radius large enough to contain a merged pair of partons. Such a requirement is also highly efficient for heavy composite Majorana neutrino decays mediated by the contact interaction, where we select only one of the two decay jets, as described later in this paper. This final selection, considered for the first time in a search for heavy neutrinos, could improve the sensitivity of searches for heavy neutrinos in the framework of other models, such as the one considered in Refs. [19,20].2The CMS detectorThe central feature of the CMS apparatus is a superconducting solenoid, of 6 m internal diameter, providing a field of 3.8 T. Within the field volume are the inner tracker, the crystal electromagnetic calorimeter (ECAL), and the brass and scintillator hadron calorimeter (HCAL). The inner tracker is composed of a pixel detector and a silicon strip tracker, and measures charged-particle trajectories in the pseudorapidity range |η|<2.5. The finely segmented ECAL consists of nearly 76000 lead-tungstate crystals that provide coverage up to |η|=3.0. The HCAL consists of a sampling calorimeter, which utilizes alternating layers of brass as an absorber and plastic scintillator as an active material, covering the range |η|<3, and is extended to |η|<5 by a forward hadron calorimeter. The muon system covers the region |η|<2.4 and consists of up to four planes of gas ionization muon detectors installed outside the solenoid and sandwiched between the layers of the steel flux-return yoke. A detailed description of the CMS detector can be found elsewhere [22].3Data samples and simulationMonte Carlo (MC) event generators are used to simulate the signal and the SM background processes. The MC samples for the signal are generated at LO with CalcHEP (v3.6) [23] for four values of the parameter Λ: 1, 5, 9, and 13 TeV and six values of the heavy composite Majorana neutrino mass: 0.5, 1.5, 2.5, 3.5, 4.5, and 6.5 TeV, but only for the cases in which mNℓ is lower than Λ. The signal samples produced with Λ=9TeV are used as reference samples in the analysis, while the samples generated with other values of Λ are used to study how the signal efficiency changes, as discussed in Section 4.The simulations for the processes tt‾, tW, and t‾W (the latter two referred as tW in the rest of the paper) are performed at next-to-the-leading order (NLO) with powheg (v2) [24–26], while the Drell–Yan (DY) and the W+jets samples are generated with MadGraph5_amc@nlo (v5.2) [27]. The WW, WZ, and ZZ processes are produced with pythia (v8.2) [28] and are normalized to NLO.The NNPDF 3.0 [29] parton distribution functions (PDF) are used, and all simulated samples use the pythia program with the CUETP8M1 tune [30] to describe parton showering and hadronization. Additional collisions in the same or adjacent bunch crossings (pileup) are taken into account by superimposing simulated minimum bias interactions onto the hard scattering process, with a number distribution matching that observed in data. Simulated events are propagated through the full Geant4 based simulation [31] of the CMS detector.4Event selectionSingle-lepton triggers that require either an electron with transverse momentum pT>105GeV or a muon with pT>50GeV within |η|<2.4, are thus used to select events in the eeqq‾′ and μμqq‾′ channels, respectively. As the signal is characterized by high-momentum leptons in the final state, the difference in trigger thresholds does not affect the relative signal sensitivity.Electrons are reconstructed as superclusters in the ECAL associated with tracks in the tracking detector [32]. Requirements on energy deposits in the calorimeter and number of track measurements are imposed to distinguish prompt electrons from charged pions and from electrons produced by photon conversions. Muons are reconstructed using the inner tracker and muon detectors [33]. Quality requirements, based on the minimum number of measurements in the silicon tracker, pixel detector, and muon detectors are applied in order to suppress backgrounds from decays in flight of hadrons and from hadron shower remnants that reach the muon system. We require exactly two electrons or exactly two muons and the two leptons must come from the same vertex. The pT of the leading (subleading) electron is required to be higher than 110 (35) GeV; the corresponding threshold for muons is 53 (30) GeV. All lepton candidates have to be reconstructed within |η|<2.4 and to pass isolation requirements, as specified in [32,33] in order to reduce background from misidentified jets.Jets are reconstructed using the anti-kT clustering algorithm [34,35] applied to the objects reconstructed with the particle-flow (PF) algorithm [36]. The latter combines information from all CMS subdetectors and reconstructs individual particles in the event (electrons, muons, photons, neutral and charged hadrons). Jets are reconstructed with a distance parameter of R=0.8, and are referred to as “large-radius jets” (and labelled by the symbol “J”) in the rest of the text. This distance parameter is suitable for reconstructing jets that originate from both gauge and contact interactions. The large-radius jets are required to have a pT>190GeV, |η|<2.4, and to be separated from leptons by ΔR=(Δη)2+(Δϕ)2>0.8, where ϕ is the azimuthal angle.Using MC signal samples we find that requiring one or more large-radius jets guarantees high signal efficiency for events with two leptons (greater than 95% for heavy composite Majorana neutrinos of masses above 1 TeV) and is suitable for Nℓ decays through both the gauge and the contact interactions. The signal region for the search for heavy composite Majorana neutrinos is defined by requiring two leptons, selected without specifying the charge, with invariant mass mℓℓ>300GeV and at least one large-radius jet satisfying the previously described requirements. The requirement on mℓℓ is introduced in order to reduce the DY background and part of the tt‾ background, without affecting the signal acceptance. With this selection, the total efficiency for events entering the signal region is expected to be about 50% in the eeqq‾′ channel and 75% in the μμqq‾′ channel, for masses of Nℓ greater than 1 TeV and Λ=9TeV. We find that the total signal efficiency varies by at most 25% for signal samples produced with Λ of 1 and 13 TeV, while it changes less than 3% for signal samples generated with Λ between 5 and 13 TeV. A shape-based analysis is performed, searching for evidence of a signal by considering the distribution of the mass of the two leptons and the leading large-radius jet, mℓℓJ. This variable provides good discrimination between the signal and the SM background contributions, as can be seen in Fig. 4.5Background estimationThe dominant background process is top quark pair production, tt‾, which is estimated together with the single top quark tW contribution. These two sources of background are always considered together in this analysis and the combination is referred to as tt‾+tW. The estimation is performed using a control sample in data free of signal contamination. This control sample consists of ℓℓ′qq‾′ events in which one lepton is required to be an electron and the other a muon. The acceptance and efficiency differ between muons and electrons, and we find that the overall event efficiency depends most strongly on the kinematics of the leading lepton. We therefore define samples of separate and distinct final states eμJ and μeJ, where the first named lepton is the leading one, as control samples for the signal samples eeJ and μμJ, respectively. All other requirements are the same for both the control and signal samples. We have verified that the meeJ and mμμJ distributions are well-modelled by the corresponding meμJ and mμeJ distributions using the MC samples. Fig. 3 shows good agreement between data and expectation from MC simulation for the meμJ and the mμeJ distributions. Backgrounds from processes other than tt‾+tW in these control samples are estimated from simulation and subtracted prior to being transferred to the signal region. The final tt‾+tW contribution is estimated from the mass shapes of the different flavour control regions scaled to the signal regions by transfer factors. The transfer factors depend on mℓℓJ and are estimated in bins corresponding to those of Fig. 3, which are then used for the final mass distributions in the signal regions. They are evaluated using MC simulation and account for differences in acceptances and efficiencies of selected eμqq‾′ and μeqq‾′ events of the control regions with respect to the selected eeqq‾′ and μμqq‾′ events of the signal regions.The DY process gives rise to another source of background when two leptons are produced together with initial-state radiation that results in a jet. This contribution is estimated from the MC simulation normalised to data in the signal-free region around the Z boson mass peak given by 80<M(ℓℓ)<100GeV. In order to check the validity of the measured normalization factors for masses above the Z boson mass peak, we compare the data with the MC prediction in the signal-depleted region given by 100<M(ℓℓ)<300GeV. We find that the normalisation factors vary by 8% between these two mass ranges, and we use this value to assign a systematic uncertainty. The statistical and systematic uncertainties of the normalisation factor are then combined with the statistical uncertainty of the DY simulation to estimate the total systematic uncertainty.Multijet events with at least three jets may enter the signal or control region for estimating backgrounds related to top quarks if two of these jets are misidentified as leptons. The contamination due to this process is found to be negligible because of the low rate at which jets are misidentified as leptons. We verify this with a method developed in the CMS search for Z′-like resonances in electron pair or muon pair final states [37]. Nonisolated lepton candidates selected from data are weighted by a correction factor to extrapolate the final contribution to the signal region. The correction factor is the rate of a nonisolated lepton to pass the full selection and is measured from data as a function of pT and η.The other SM backgrounds, arising from W+jets and diboson production, are small (∼5% of the total), and their contribution is taken directly from MC simulation.6Systematic uncertaintiesThe systematic uncertainties are taken into account through their effect on the mass distribution and the yield normalisation. The uncertainty in the calculation of the tt‾+tW and DY backgrounds is dominated by the statistical uncertainty of the control samples used for the estimations. The contamination from sub dominant backgrounds in these control regions has a negligible effect on the systematic uncertainty. The uncertainties related to the background estimations vary between 20 and 30% (40 and 100%) from the lowest to the highest mass bin in which the tt‾+tW (DY) processes contribute. The uncertainty associated with the estimation of the W+jets and diboson backgrounds, which together represent only a small fraction of the events in the signal region, has a negligible impact on the limit calculation. The uncertainty in the acceptance associated with the PDFs is evaluated in accordance with the PDF4LHC recommendations [38], using the PDF4LHC15 Hessian PDF set with 100 eigenvectors. The PDF uncertainty amounts to 10% for the DY background and 4% for the signal. Uncertainties related to the trigger, and to lepton reconstruction, identification, and isolation efficiencies are measured by dedicated analyses using Z→ℓℓ events [32,33] and amount on average to 3% (6%) for the background and 4% (10%) for the signal in the electron (muon) channel. The systematic uncertainty in the lepton energy scale and resolution are found to be approximately 5% (6%) for the background and 3% (4%) for the signal. The uncertainty related to jet energy scale amounts to 3% (4%) for the background of the eeqq‾′ (μμqq‾′) channel, and around 1% for the signal regardless of the channel. Uncertainties related to jet energy resolution correspond to 2 and 4% for the background and the signal, respectively, in both channels. The imperfect modelling of pileup interactions leads to a systematic uncertainty of about 4% for background and 2% for signal. The uncertainty in the total integrated luminosity amounts to 2.3% for the 2015 data [13].7ResultsTable 1 lists the estimated background yields, the total number of observed events for each channel and the number of events expected for the signal, considering Λ=9TeV and two hypotheses for the masses of Nℓ: 1.5 and 2.5 TeV. Table 1 (upper) shows the number of events integrated over all values of the reconstructed mass, while Table 1 (lower) shows the agreement for the high sensitivity region above 1.4 TeV.Distributions of mℓℓJ are shown in Fig. 4, where the data are compared with the estimated SM backgrounds and two different signal hypotheses are superimposed. The figures are for the eeqq‾′ (left) and μμqq‾′ (right) channels. The uncertainties on the background estimation are the combination of the statistical and the systematic uncertainties.The observations are in agreement with the background expectations from the SM. We use a modified frequentist CLs criterion [39,40] to set an upper limit at 95% CL on the product cross section for production of the heavy composite Majorana neutrino produced in association with a lepton and the branching fraction for the Nℓ decay to a same-flavour lepton and two quarks, (pp→ℓNℓ)B(Nℓ→ℓqq‾′). We also set upper limits on the compositeness scale Λ. The mℓℓJ distributions for the MC signal, SM backgrounds, and observed data are used as input in the limit computation together with the systematic uncertainties discussed in Section 6, which are treated as uncorrelated among the bins of the mass distribution, if they are related to the background estimations, and correlated otherwise.The observed and expected upper limits on σ(pp→ℓNℓ)B(Nℓ→ℓqq‾′) as a function of the mass of the heavy composite Majorana neutrino are shown in Fig. 5. The bands represent expected variations of the limit to one and two standard deviation(s). The solid blue curve indicates the theoretical prediction of σ(pp→ℓNℓ)B(Nℓ→ℓqq‾′) for mNℓ=Λ, while the light red textured curves show the same theoretical prediction for three Λ values ranging from 6 to 12 TeV. The corresponding exclusion limits on the compositeness scale Λ are displayed in Fig. 6. At low Nℓ masses, values of the compositeness scale Λ can be excluded up to 11.5 and 10.0 TeV in the eeqq‾′ and μμqq‾′ channel, respectively. The sensitivity to Λ decreases at higher masses of Nℓ. For the case of mNℓ=Λ, the resulting exclusion limits on mNℓ are up to 4.60 (4.55) TeV in the eeqq‾′ channel and 4.70 (4.75) TeV in the μμqq‾′ channel, considering the observation (SM expectation). When deriving these limits, we assume that the signal efficiency is independent of Λ. This hypothesis has been validated for signal samples produced with Λ between 5 and 13 TeV, while for samples with Λ lower than 5 TeV the difference can be up to 25%. Despite this difference, the whole region in Fig. 6 remains excluded because of the much higher cross section for lower Λ points. We further verify that the upper limits on mNℓ for a given Λ value vary at most by 5% comparing the cases in which the MC signal mℓℓJ distributions produced with Λ equal to 5 and 13 TeV are used as input in the limit calculation.8SummaryA search for physics beyond the standard model has been performed in the framework of a new model [12] predicting a heavy Majorana neutrino, Nℓ, that originates from a composite-fermion scenario and is produced in association with a matched-flavour charged lepton. The measurement is performed analysing the final state with two leptons, selected without specifying the charge, and at least one large-radius jet, a signature not previously utilized in searches for heavy neutrinos. The data set used corresponds to an integrated luminosity of 2.3fb−1 collected with the CMS detector at the LHC in pp collisions at s=13 TeV. Good agreement between the data and the standard model prediction is observed. Upper limits are set at 95% confidence level both on the product of the cross section σ(pp→ℓNℓ) and the branching fraction B(Nℓ→ℓqq‾′), and on the compositeness scale Λ, as a function of mNℓ, ℓ being an electron or a muon. For the representative case Λ=mNℓ, Ne masses up to 4.60 TeV and Nμ masses up to 4.70 TeV are excluded. This measurement represents the first search that places constraints on the model described in Ref. [12].AcknowledgementsWe 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 centres 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).References[1]J.C.PatiA.SalamJ.A.StrathdeeAre quarks composite?Phys. 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