PLB30671S0370-2693(14)00869-710.1016/j.physletb.2014.11.059The AuthorsExperimentsFig. 1Distribution of the reconstructed four-lepton mass for the (upper left) 4e, (upper right) 4μ, (lower left) 2e2μ, and (lower right) combined ℓℓττ decay channels. The data sample corresponds to an integrated luminosity of 19.6 fb−1. Points represent the data, the shaded histograms labeled ZZ represent the powheg+gg2zz+pythia predictions for ZZ signal, the histograms labeled WZ/Z+jets show the background, which is estimated from data, as described in the text.Fig. 2(upper left) Distribution of the reconstructed four-lepton mass for the sum of the 4e, 4μ, and 2e2μ decay channels. (upper right) Reconstructed Z1 mass. The correlation between the reconstructed Z1 and Z2 masses for the (lower left) combined 4e, 4μ, and 2e2μ final states and (lower right) for ℓℓττ final states. Points represent the data, the shaded histograms labeled ZZ represent the powheg+gg2zz+pythia predictions for ZZ signal, the histograms labeled WZ/Z+jets show background, which is estimated from data, as described in the text.Fig. 3Differential cross sections normalized to the fiducial cross section for the combined 4e, 4μ, and 2e2μ decay channels as a function of pT for (upper left) the highest pT lepton in the event, (upper right) the Z1, and (lower left) the ZZ system. Figure (lower right) shows the normalized dσ/dmZZ distribution. Points represent the data, and the shaded histograms labeled ZZ represent the powheg+gg2zz+pythia predictions for ZZ signal, while the solid curves correspond to results of the mcfm calculations. The bottom part of each subfigure represents the ratio of the measured cross section to the expected one from powheg+gg2zz+pythia (black crosses with solid symbols) and mcfm (red crosses). The shaded areas on all the plots represent the full uncertainties calculated as the quadrature sum of the statistical and systematic uncertainties, whereas the crosses represent the statistical uncertainties only. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)Fig. 4Differential cross section normalized to the fiducial cross section for the combined 4e, 4μ, and 2e2μ decay channels as a function of (top) azimuthal separation of the two Z bosons and (bottom) ΔR between the Z-bosons. Points represent the data, and the shaded histograms labeled ZZ represent the powheg+gg2zz+pythia predictions for ZZ signal, while the solid curves correspond to results of the mcfm calculations. The bottom part of each subfigure represents the ratio of the measured cross section to the expected one from powheg+gg2zz+pythia (black crosses with solid symbols) and mcfm (red crosses). The shaded areas on all the plots represent the full uncertainties calculated as the quadrature sum of the statistical and systematic uncertainties, whereas the crosses represent the statistical uncertainties only. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)Fig. 5Distribution of the four-lepton reconstructed mass for the combined 4e, 4μ, and 2e2μ channels. Points represent the data, the shaded histogram labeled ZZ represents the powheg+gg2zz+pythia predictions for ZZ signal, the histograms labeled WZ/Z+jets shows background, which is estimated from data, as described in the text. The dashed and dotted histograms indicate the results of the sherpa simulation for the SM (f4Z=0) and in the presence of an ATGC (f4Z=0.015) with all the other anomalous couplings set to zero. The last bin includes all entries with masses above 1000 GeV.Fig. 6Two-dimensional exclusion limits at 68% (dashed contour) and 95% (solid contour) CL on the ZZZ and ZZγ ATGCs. The top (bottom) plot shows the exclusion contour in the (f4(5)Z,f4(5)γ) parameter planes. The solid dot shows where the likelihood reaches its maximum. The values of couplings outside of contours are excluded at the corresponding confidence level. The lines in the middle represent one-dimensional limits. No form factor is used.Table 1The expected yields of ZZ and background events, as well as their sum (“Total expected”) are compared with the observed yields for each decay channel. The statistical and systematic uncertainties are also shown.Decay channelExpected ZZ yieldBackgroundTotal expectedObserved4e55.28±0.25±7.642.16±0.26±0.8857.44±0.37±7.69544μ77.32±0.29±10.081.19±0.36±0.4878.51±0.49±10.09752e2μ136.09±0.59±17.502.35±0.34±0.93138.44±0.70±17.52148eeτhτh2.46±0.03±0.323.46±0.34±1.045.92±0.36±1.1510μμτhτh2.80±0.03±0.343.89±0.37±1.176.69±0.39±1.3010eeτeτh2.79±0.03±0.363.87±1.26±1.166.66±1.34±1.299μμτeτh2.87±0.03±0.371.49±0.67±0.604.36±0.71±0.732eeτμτh3.27±0.03±0.421.47±0.41±0.444.74±0.43±0.632μμτμτh3.81±0.03±0.501.55±0.43±0.465.36±0.46±0.705eeτeτμ2.23±0.03±0.293.04±1.32±1.505.27±1.40±1.614μμτeτμ2.41±0.03±0.320.74±0.51±0.373.15±0.54±0.515Total ℓℓττ22.65±0.05±2.9419.51±2.15±5.8542.16±2.28±6.8747Table 2The total ZZ production cross section as measured in each decay channel and for the combination of all channels.Decay channelTotal cross section, pb4e7.2−0.9+1.0 (stat)−0.5+0.6 (syst)±0.4(theo)±0.2 (lumi)4μ7.3−0.8+0.8 (stat)−0.5+0.6 (syst)±0.4(theo)±0.2 (lumi)2e2μ8.1−0.6+0.7 (stat)−0.5+0.6 (syst)±0.4(theo)±0.2 (lumi)ℓℓττ7.7−1.9+2.1 (stat)−1.8+2.0 (syst)±0.4(theo)±0.2 (lumi)Combined7.7±0.5 (stat)−0.4+0.5 (syst)±0.4(theo)±0.2 (lumi)Measurement of the pp→ZZ production cross section and constraints on anomalous triple gauge couplings in four-lepton final states at s=8 TeVCMS Collaboration⋆V.KhachatryanA.M.SirunyanA.TumasyanYerevan Physics Institute, Yerevan, ArmeniaYerevan Physics InstituteYerevanArmeniaW.AdamT.BergauerM.DragicevicJ.EröC.Fabjan1M.FriedlR.Frühwirth1V.M.GheteC.HartlN.HörmannJ.HrubecM.Jeitler1W.KiesenhoferV.KnünzM.Krammer1I.KrätschmerD.LikoI.MikulecD.Rabady2B.RahbaranH.RohringerR.SchöfbeckJ.StraussA.TaurokW.Treberer-TreberspurgW.WaltenbergerC.-E.Wulz1Institut für Hochenergiephysik der OeAW, Wien, AustriaInstitut für Hochenergiephysik der OeAWWienAustria1Also at Vienna University of Technology, Vienna, Austria.2Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland.V.MossolovN.ShumeikoJ.Suarez GonzalezNational Centre for Particle and High Energy Physics, Minsk, BelarusNational Centre for Particle and High Energy PhysicsMinskBelarusS.AlderweireldtM.BansalS.BansalT.CornelisE.A.De WolfX.JanssenA.KnutssonS.LuyckxS.OchesanuB.RolandR.RougnyM.Van De KlundertH.Van HaevermaetP.Van MechelenN.Van RemortelA.Van SpilbeeckUniversiteit Antwerpen, Antwerpen, BelgiumUniversiteit AntwerpenAntwerpenBelgiumF.BlekmanS.BlyweertJ.D'HondtN.DaciN.HeracleousA.KalogeropoulosJ.KeaveneyT.J.KimS.LowetteM.MaesA.OlbrechtsQ.PythonD.StromS.TavernierW.Van DoninckP.Van MuldersG.P.Van OnsemI.VillellaVrije Universiteit Brussel, Brussel, BelgiumVrije Universiteit BrusselBrusselBelgiumC.CaillolB.ClerbauxG.De LentdeckerD.DoburL.FavartA.P.R.GayA.GrebenyukA.LéonardA.MohammadiL.Perniè2T.ReisT.SevaL.ThomasC.Vander VeldeP.VanlaerJ.WangUniversité Libre de Bruxelles, Bruxelles, BelgiumUniversité Libre de BruxellesBruxellesBelgiumV.AdlerK.BeernaertL.BenucciA.CimminoS.CostantiniS.CrucyS.DildickA.FagotG.GarciaB.KleinJ.MccartinA.A.Ocampo RiosD.RyckboschS.Salva DiblenM.SigamaniN.StrobbeF.ThyssenM.TytgatE.YazganN.ZaganidisGhent University, Ghent, BelgiumGhent UniversityGhentBelgiumS.BasegmezC.Beluffi3G.BrunoR.CastelloA.CaudronL.CeardG.G.Da SilveiraC.DelaereT.du PreeD.FavartL.ForthommeA.Giammanco4J.HollarP.JezM.KommV.LemaitreJ.LiaoC.NuttensD.PaganoA.PinK.PiotrzkowskiA.Popov5L.QuertenmontM.SelvaggiM.Vidal MaronoJ.M.Vizan GarciaUniversité Catholique de Louvain, Louvain-la-Neuve, BelgiumUniversité Catholique de LouvainLouvain-la-NeuveBelgium3Also at Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Université de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France.4Also at National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.5Also at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia.N.BeliyT.CaebergsE.DaubieG.H.HammadUniversité de Mons, Mons, BelgiumUniversité de MonsMonsBelgiumG.A.AlvesM.Correa Martins JuniorT.Dos Reis MartinsM.E.PolCentro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, BrazilCentro Brasileiro de Pesquisas FisicasRio de JaneiroBrazilW.L.Aldá JúniorW.CarvalhoJ.Chinellato6A.CustódioE.M.Da CostaD.De Jesus DamiaoC.De Oliveira MartinsS.Fonseca De SouzaH.MalbouissonM.MalekD.Matos FigueiredoL.MundimH.NogimaW.L.Prado Da SilvaJ.SantaolallaA.SantoroA.SznajderE.J.Tonelli Manganote6A.Vilela PereiraUniversidade do Estado do Rio de Janeiro, Rio de Janeiro, BrazilUniversidade do Estado do Rio de JaneiroRio de JaneiroBrazil6Also at Universidade Estadual de Campinas, Campinas, Brazil.C.A.BernardesbF.A.Diasa7T.R.Fernandez Perez TomeiaE.M.GregoresbP.G.MercadantebS.F.NovaesaSandra S.PadulaaaUniversidade Estadual Paulista, São Paulo, BrazilUniversidade Estadual PaulistaSão PauloBrazilbUniversidade Federal do ABC, São Paulo, BrazilUniversidade Federal do ABCSão PauloBrazil7Also at California Institute of Technology, Pasadena, USA.A.AleksandrovV.Genchev2P.IaydjievA.MarinovS.PiperovM.RodozovG.SultanovM.VutovaInstitute for Nuclear Research and Nuclear Energy, Sofia, BulgariaInstitute for Nuclear Research and Nuclear EnergySofiaBulgariaA.DimitrovI.GlushkovR.HadjiiskaV.KozhuharovL.LitovB.PavlovP.PetkovUniversity of Sofia, Sofia, BulgariaUniversity of SofiaSofiaBulgariaJ.G.BianG.M.ChenH.S.ChenM.ChenR.DuC.H.JiangD.LiangS.LiangR.Plestina8J.TaoX.WangZ.WangInstitute of High Energy Physics, Beijing, ChinaInstitute of High Energy PhysicsBeijingChina8Also at Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3–CNRS, Palaiseau, France.C.AsawatangtrakuldeeY.BanY.GuoQ.LiW.LiS.LiuY.MaoS.J.QianD.WangL.ZhangW.ZouState Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, ChinaState Key Laboratory of Nuclear Physics and TechnologyPeking UniversityBeijingChinaC.AvilaL.F.Chaparro SierraC.FlorezJ.P.GomezB.Gomez MorenoJ.C.SanabriaUniversidad de Los Andes, Bogota, ColombiaUniversidad de Los AndesBogotaColombiaN.GodinovicD.LelasD.PolicI.PuljakTechnical University of Split, Split, CroatiaTechnical University of SplitSplitCroatiaZ.AntunovicM.KovacUniversity of Split, Split, CroatiaUniversity of SplitSplitCroatiaV.BrigljevicK.KadijaJ.LueticD.MekterovicL.SudicInstitute Rudjer Boskovic, Zagreb, CroatiaInstitute Rudjer BoskovicZagrebCroatiaA.AttikisG.MavromanolakisJ.MousaC.NicolaouF.PtochosP.A.RazisUniversity of Cyprus, Nicosia, CyprusUniversity of CyprusNicosiaCyprusM.BodlakM.FingerM.FingerJr.Charles University, Prague, Czech RepublicCharles UniversityPragueCzech RepublicY.Assran9A.Ellithi Kamel10M.A.Mahmoud11A.Radi1213Academy 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 PhysicsCairoEgypt9Also at Suez University, Suez, Egypt.10Also at Cairo University, Cairo, Egypt.11Also at Fayoum University, El-Fayoum, Egypt.12Also at British University in Egypt, Cairo, Egypt.13Now at Ain Shams University, Cairo, Egypt.M.KadastikM.MurumaaM.RaidalA.TikoNational Institute of Chemical Physics and Biophysics, Tallinn, EstoniaNational Institute of Chemical Physics and BiophysicsTallinnEstoniaP.EerolaG.FediM.VoutilainenDepartment of Physics, University of Helsinki, Helsinki, FinlandDepartment of PhysicsUniversity of HelsinkiHelsinkiFinlandJ.HärkönenV.KarimäkiR.KinnunenM.J.KortelainenT.LampénK.Lassila-PeriniS.LehtiT.LindénP.LuukkaT.MäenpääT.PeltolaE.TuominenJ.TuominiemiE.TuovinenL.WendlandHelsinki Institute of Physics, Helsinki, FinlandHelsinki Institute of PhysicsHelsinkiFinlandT.TuuvaLappeenranta University of Technology, Lappeenranta, FinlandLappeenranta University of TechnologyLappeenrantaFinlandM.BesanconF.CoudercM.DejardinD.DenegriB.FabbroJ.L.FaureC.FavaroF.FerriS.GanjourA.GivernaudP.GrasG.Hamel de MonchenaultP.JarryE.LocciJ.MalclesA.NayakJ.RanderA.RosowskyM.TitovDSM/IRFU, CEA/Saclay, Gif-sur-Yvette, FranceDSM/IRFUCEA/SaclayGif-sur-YvetteFranceS.BaffioniF.BeaudetteP.BussonC.CharlotT.DahmsM.DalchenkoL.DobrzynskiN.FilipovicA.FlorentR.Granier de CassagnacL.MastrolorenzoP.MinéC.MironovI.N.NaranjoM.NguyenC.OchandoP.PaganiniR.SalernoJ.B.SauvanY.SiroisC.VeelkenY.YilmazA.ZabiLaboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, FranceLaboratoire Leprince-RinguetEcole PolytechniqueIN2P3-CNRSPalaiseauFranceJ.-L.Agram14J.AndreaA.AubinD.BlochJ.-M.BromE.C.ChabertC.CollardE.Conte14J.-C.Fontaine14D.GeléU.GoerlachC.GoetzmannA.-C.Le BihanP.Van HoveInstitut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Université de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, FranceInstitut Pluridisciplinaire Hubert CurienUniversité de StrasbourgUniversité de Haute Alsace MulhouseCNRS/IN2P3StrasbourgFrance14Also 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.BeauceronN.BeaupereG.Boudoul2S.BrochetC.A.Carrillo MontoyaJ.ChasseratR.ChiericiD.Contardo2P.DepasseH.El MamouniJ.FanJ.FayS.GasconM.GouzevitchB.IlleT.KurcaM.LethuillierL.MirabitoS.PerriesJ.D.Ruiz AlvarezD.SabesL.SgandurraV.SordiniM.Vander DoncktP.VerdierS.ViretH.XiaoUniversité 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 LyonVilleurbanneFranceZ.Tsamalaidze15Institute of High Energy Physics and Informatization, Tbilisi State University, Tbilisi, GeorgiaInstitute of High Energy Physics and InformatizationTbilisi State UniversityTbilisiGeorgia15Also at Joint Institute for Nuclear Research, Dubna, Russia.C.AutermannS.BeranekM.BontenackelsB.CalpasM.EdelhoffL.FeldO.HindrichsK.KleinA.OstapchukA.PerieanuF.RaupachJ.SammetS.SchaelD.SprengerH.WeberB.WittmerV.Zhukov5RWTH Aachen University, I. Physikalisches Institut, Aachen, GermanyRWTH Aachen UniversityI. Physikalisches InstitutAachenGermanyM.AtaJ.CaudronE.Dietz-LaursonnD.DuchardtM.ErdmannR.FischerA.GüthT.HebbekerC.HeidemannK.HoepfnerD.KlingebielS.KnutzenP.KreuzerM.MerschmeyerA.MeyerM.OlschewskiK.PadekenP.PapaczH.ReithlerS.A.SchmitzL.SonnenscheinD.TeyssierS.ThüerM.WeberRWTH Aachen University, III. Physikalisches Institut A, Aachen, GermanyRWTH Aachen UniversityIII. Physikalisches Institut AAachenGermanyV.CherepanovY.ErdoganG.FlüggeH.GeenenM.GeislerW.Haj AhmadF.HoehleB.KargollT.KressY.KuesselJ.Lingemann2A.NowackI.M.NugentL.PerchallaO.PoothA.StahlRWTH Aachen University, III. Physikalisches Institut B, Aachen, GermanyRWTH Aachen UniversityIII. Physikalisches Institut BAachenGermanyI.AsinN.BartosikJ.BehrW.BehrenhoffU.BehrensA.J.BellM.Bergholz16A.BethaniK.BorrasA.BurgmeierA.CakirL.CalligarisA.CampbellS.ChoudhuryF.CostanzaC.Diez PardosS.DoolingT.DorlandG.EckerlinD.EcksteinT.EichhornG.FluckeJ.Garay GarciaA.GeiserP.GunnelliniJ.HaukG.HellwigM.HempelD.HortonH.JungM.KasemannP.KatsasJ.KieselerC.KleinwortD.KrückerW.LangeJ.LeonardK.LipkaA.LobanovW.Lohmann16B.LutzR.MankelI.MarfinI.-A.Melzer-PellmannA.B.MeyerJ.MnichA.MussgillerS.Naumann-EmmeO.NovgorodovaF.NowakE.NtomariH.PerreyD.PitzlR.PlacakyteA.RasperezaP.M.Ribeiro CiprianoE.RonM.Ö.SahinJ.Salfeld-NebgenP.SaxenaR.Schmidt16T.Schoerner-SadeniusM.SchröderS.SpannagelA.D.R.Vargas TrevinoR.WalshC.WissingDeutsches Elektronen-Synchrotron, Hamburg, GermanyDeutsches Elektronen-SynchrotronHamburgGermany16Also at Brandenburg University of Technology, Cottbus, Germany.M.Aldaya MartinV.BlobelM.Centis VignaliJ.ErfleE.GaruttiK.GoebelM.GörnerM.GosselinkJ.HallerR.S.HöingH.KirschenmannR.KlannerR.KoglerJ.LangeT.LapsienT.LenzI.MarchesiniJ.OttT.PeifferN.PietschD.RathjensC.SanderH.SchettlerP.SchleperE.SchlieckauA.SchmidtM.SeidelJ.Sibille17V.SolaH.StadieG.SteinbrückD.TroendleE.UsaiL.VanelderenUniversity of Hamburg, Hamburg, GermanyUniversity of HamburgHamburgGermany17Also at The University of Kansas, Lawrence, USA.C.BarthC.BausJ.BergerC.BöserE.ButzT.ChwalekW.De BoerA.DescroixA.DierlammM.FeindtF.Hartmann2T.Hauth2U.HusemannI.Katkov5A.Kornmayer2E.KuznetsovaP.Lobelle PardoM.U.MozerTh.MüllerA.NürnbergG.QuastK.RabbertzF.RatnikovS.RöckerH.J.SimonisF.M.StoberR.UlrichJ.Wagner-KuhrS.WayandT.WeilerR.WolfInstitut für Experimentelle Kernphysik, Karlsruhe, GermanyInstitut für Experimentelle KernphysikKarlsruheGermanyG.AnagnostouG.DaskalakisT.GeralisV.A.GiakoumopoulouA.KyriakisD.LoukasA.MarkouC.MarkouA.PsallidasI.Topsis-GiotisInstitute of Nuclear and Particle Physics (INPP), NCSR Demokritos, Aghia Paraskevi, GreeceInstitute of Nuclear and Particle Physics (INPP)NCSR DemokritosAghia ParaskeviGreeceL.GouskosA.PanagiotouN.SaoulidouE.StiliarisUniversity of Athens, Athens, GreeceUniversity of AthensAthensGreeceX.AslanoglouI.EvangelouG.FlourisC.FoudasP.KokkasN.ManthosI.PapadopoulosE.ParadasUniversity of Ioánnina, Ioánnina, GreeceUniversity of IoánninaIoánninaGreeceG.BenczeC.HajduP.HidasD.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 Eötvös Loránd University, Budapest, Hungary.N.BeniS.CzellarJ.Karancsi20J.MolnarJ.PalinkasZ.SzillasiInstitute of Nuclear Research ATOMKI, Debrecen, HungaryInstitute of Nuclear Research ATOMKIDebrecenHungary20Also at University of Debrecen, Debrecen, Hungary.P.RaicsZ.L.TrocsanyiB.UjvariUniversity of Debrecen, Debrecen, HungaryUniversity of DebrecenDebrecenHungaryS.K.SwainNational Institute of Science Education and Research, Bhubaneswar, IndiaNational Institute of Science Education and ResearchBhubaneswarIndiaS.B.BeriV.BhatnagarN.DhingraR.GuptaA.K.KalsiM.KaurM.MittalN.NishuJ.B.SinghPanjab University, Chandigarh, IndiaPanjab UniversityChandigarhIndiaAshokKumarArunKumarS.AhujaA.BhardwajB.C.ChoudharyA.KumarS.MalhotraM.NaimuddinK.RanjanV.SharmaUniversity of Delhi, Delhi, IndiaUniversity of DelhiDelhiIndiaS.BanerjeeS.BhattacharyaK.ChatterjeeS.DuttaB.GomberSa.JainSh.JainR.KhuranaA.ModakS.MukherjeeD.RoyS.SarkarM.SharanSaha Institute of Nuclear Physics, Kolkata, IndiaSaha Institute of Nuclear PhysicsKolkataIndiaA.AbdulsalamD.DuttaS.KailasV.KumarA.K.Mohanty2L.M.PantP.ShuklaA.TopkarBhabha Atomic Research Centre, Mumbai, IndiaBhabha Atomic Research CentreMumbaiIndiaT.AzizS.BanerjeeR.M.ChatterjeeR.K.DewanjeeS.DugadS.GangulyS.GhoshM.GuchaitA.Gurtu21G.KoleS.KumarM.Maity22G.MajumderK.MazumdarG.B.MohantyB.ParidaK.SudhakarN.Wickramage23Tata Institute of Fundamental Research, Mumbai, IndiaTata Institute of Fundamental ResearchMumbaiIndia21Now at King Abdulaziz University, Jeddah, Saudi Arabia.22Also at University of Visva-Bharati, Santiniketan, India.23Also at University of Ruhuna, Matara, Sri Lanka.H.BakhshiansohiH.BehnamianS.M.Etesami24A.Fahim25R.GoldouzianA.JafariM.KhakzadM.Mohammadi NajafabadiM.NaseriS.Paktinat MehdiabadiB.Safarzadeh26M.ZeinaliInstitute for Research in Fundamental Sciences (IPM), Tehran, IranInstitute for Research in Fundamental Sciences (IPM)TehranIran24Also at Isfahan University of Technology, Isfahan, Iran.25Also at Sharif University of Technology, Tehran, Iran.26Also at Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran.M.FelciniM.GrunewaldUniversity College Dublin, Dublin, IrelandUniversity College DublinDublinIrelandM.AbbresciaabL.BarboneabC.CalabriaabS.S.ChhibraabA.ColaleoaD.CreanzaacN.De FilippisacM.De PalmaabL.FioreaG.IaselliacG.MaggiacM.MaggiaS.MyacS.NuzzoabN.PacificoaA.PompiliabG.PuglieseacR.Radognaab2G.SelvaggiabL.Silvestrisa2G.SinghabR.VendittiabP.VerwilligenaG.ZitoaaINFN Sezione di Bari, Bari, ItalyINFN Sezione di BariBariItalybUniversità di Bari, Bari, ItalyUniversità di BariBariItalycPolitecnico di Bari, Bari, ItalyPolitecnico di BariBariItalyG.AbbiendiaA.C.BenvenutiaD.BonacorsiabS.Braibant-GiacomelliabL.BrigliadoriabR.CampaniniabP.CapiluppiabA.CastroabF.R.CavalloaG.CodispotiabM.CuffianiabG.M.DallavalleaF.FabbriaA.FanfaniabD.FasanellaabP.GiacomelliaC.GrandiaL.GuiducciabS.MarcelliniaG.Masettia2A.MontanariaF.L.NavarriaabA.PerrottaaF.PrimaveraabA.M.RossiabT.RovelliabG.P.SiroliabN.TosiabR.TravagliniabaINFN Sezione di Bologna, Bologna, ItalyINFN Sezione di BolognaBolognaItalybUniversità di Bologna, Bologna, ItalyUniversità di BolognaBolognaItalyS.AlbergoabG.CappelloaM.ChiorboliabS.CostaabF.Giordanoa2R.PotenzaabA.TricomiabC.TuveabaINFN Sezione di Catania, Catania, ItalyINFN Sezione di CataniaCataniaItalybUniversità di Catania, Catania, ItalyUniversità di CataniaCataniaItalycCSFNSM, Catania, ItalyCSFNSMCataniaItalyG.BarbagliaV.CiulliabC.CivininiaR.D'AlessandroabE.FocardiabE.GalloaS.GonziabV.Goriab2P.LenziabM.MeschiniaS.PaolettiaG.SguazzoniaA.TropianoabaINFN Sezione di Firenze, Firenze, ItalyINFN Sezione di FirenzeFirenzeItalybUniversità di Firenze, Firenze, ItalyUniversità di FirenzeFirenzeItalyL.BenussiS.BiancoF.FabbriD.PiccoloINFN Laboratori Nazionali di Frascati, Frascati, ItalyINFN Laboratori Nazionali di FrascatiFrascatiItalyF.FerroaM.Lo VetereabE.RobuttiaS.TosiabaINFN Sezione di Genova, Genova, ItalyINFN Sezione di GenovaGenovaItalybUniversità di Genova, Genova, ItalyUniversità di GenovaGenovaItalyM.E.DinardoabS.Fiorendiab2S.Gennaia2R.Gerosa2A.GhezziabP.GovoniabM.T.Lucchiniab2S.MalvezziaR.A.ManzoniabA.MartelliabB.MarzocchiD.MenasceaL.MoroniaM.PaganoniabD.PedriniaS.RagazziabN.RedaelliaT.Tabarelli de FatisabaINFN Sezione di Milano-Bicocca, Milano, ItalyINFN Sezione di Milano-BicoccaMilanoItalybUniversità di Milano-Bicocca, Milano, ItalyUniversità di Milano-BicoccaMilanoItalyS.BuontempoaN.CavalloacS.Di Guidaad2F.FabozziacA.O.M.IorioabL.ListaaS.Meolaad2M.MerolaaP.Paoluccia2aINFN Sezione di Napoli, Napoli, ItalyINFN Sezione di NapoliNapoliItalybUniversità di Napoli ‘Federico II’, Napoli, ItalyUniversità di Napoli ‘Federico II’NapoliItalycUniversità della Basilicata (Potenza), Napoli, ItalyUniversità della Basilicata (Potenza)NapoliItalydUniversità G. Marconi (Roma), Napoli, ItalyUniversità G. Marconi (Roma)NapoliItalyP.AzziaN.BacchettaaD.BiselloabA.BrancaabR.CarlinabP.ChecchiaaM.Dall'OssoabT.DorigoaU.DosselliaM.GalantiabF.GaspariniabU.GaspariniabP.GiubilatoabA.GozzelinoaK.KanishchevacS.LacapraraaM.MargoniabJ.PazziniabM.PegoraroaN.PozzobonabP.RoncheseabF.SimonettoabM.TosiabA.TriossiaS.VenturaaA.ZucchettaabG.ZumerleabaINFN Sezione di Padova, Padova, ItalyINFN Sezione di PadovaPadovaItalybUniversità di Padova, Padova, ItalyUniversità di PadovaPadovaItalycUniversità di Trento (Trento), Padova, ItalyUniversità di Trento (Trento)PadovaItalyM.GabusiabS.P.RattiabC.RiccardiabP.SalviniaP.VituloabaINFN Sezione di Pavia, Pavia, ItalyINFN Sezione di PaviaPaviaItalybUniversità di Pavia, Pavia, ItalyUniversità di PaviaPaviaItalyM.BiasiniabG.M.BileiaD.CiangottiniabL.FanòabP.LaricciaabG.MantovaniabM.MenichelliaF.RomeoabA.SahaaA.SantocchiaabA.Spieziaab2aINFN Sezione di Perugia, Perugia, ItalyINFN Sezione di PerugiaPerugiaItalybUniversità di Perugia, Perugia, ItalyUniversità di PerugiaPerugiaItalyK.Androsova27P.AzzurriaG.BagliesiaJ.BernardiniaT.BoccaliaG.BroccoloacR.CastaldiaM.A.Cioccia27R.Dell'OrsoaS.DonatoacF.FioriacL.FoàacA.GiassiaM.T.Grippoa27F.LigabueacT.LomtadzeaL.MartiniabA.MessineoabC.S.Moona28F.Pallaa2A.RizziabA.Savoy-Navarroa29A.T.SerbanaP.SpagnoloaP.Squillaciotia27R.TenchiniaG.TonelliabA.VenturiaP.G.VerdiniaC.Vernieriac2aINFN Sezione di Pisa, Pisa, ItalyINFN Sezione di PisaPisaItalybUniversità di Pisa, Pisa, ItalyUniversità di PisaPisaItalycScuola Normale Superiore di Pisa, Pisa, ItalyScuola Normale Superiore di PisaPisaItaly27Also at Università degli Studi di Siena, Siena, Italy.28Also at Centre National de la Recherche Scientifique (CNRS) – IN2P3, Paris, France.29Also at Purdue University, West Lafayette, USA.L.BaroneabF.CavallariaD.Del ReabM.DiemozaM.GrassiabC.JordaaE.LongoabF.MargaroliabP.MeridianiaF.Micheliab2S.NourbakhshabG.OrgantiniabR.ParamattiaS.RahatlouabC.RovelliaF.SantanastasioabL.Soffiab2P.TraczykabaINFN Sezione di Roma, Roma, ItalyINFN Sezione di RomaRomaItalybUniversità di Roma, Roma, ItalyUniversità di RomaRomaItalyN.AmapaneabR.ArcidiaconoacS.Argiroab2M.ArneodoacR.BellanabC.BiinoaN.CartigliaaS.Casassoab2M.CostaabA.DeganoabN.DemariaaL.FincoabC.MariottiaS.MaselliaE.MiglioreabV.MonacoabM.MusichaM.M.Obertinoac2G.OrtonaabL.PacherabN.PastroneaM.PelliccioniaG.L.Pinna AngioniabA.PotenzaabA.RomeroabM.RuspaacR.SacchiabA.SolanoabA.StaianoaU.TamponiaaINFN Sezione di Torino, Torino, ItalyINFN Sezione di TorinoTorinoItalybUniversità di Torino, Torino, ItalyUniversità di TorinoTorinoItalycUniversità del Piemonte Orientale (Novara), Torino, ItalyUniversità del Piemonte Orientale (Novara)TorinoItalyS.BelforteaV.CandeliseabM.CasarsaaF.CossuttiaG.Della RiccaabB.GobboaC.La LicataabM.MaroneabD.MontaninoabA.Schizziab2T.UmerabA.ZanettiaaINFN Sezione di Trieste, Trieste, ItalyINFN Sezione di TriesteTriesteItalybUniversità di Trieste, Trieste, ItalyUniversità di TriesteTriesteItalyS.ChangA.KropivnitskayaS.K.NamKangwon National University, Chunchon, Republic of KoreaKangwon National UniversityChunchonRepublic of KoreaD.H.KimG.N.KimM.S.KimD.J.KongS.LeeY.D.OhH.ParkA.SakharovD.C.SonKyungpook National University, Daegu, Republic of KoreaKyungpook National UniversityDaeguRepublic of KoreaJ.Y.KimS.SongChonnam National University, Institute for Universe and Elementary Particles, Kwangju, Republic of KoreaChonnam National UniversityInstitute for Universe and Elementary ParticlesKwangjuRepublic of KoreaS.ChoiD.GyunB.HongM.JoH.KimY.KimB.LeeK.S.LeeS.K.ParkY.RohKorea University, Seoul, Republic of KoreaKorea UniversitySeoulRepublic of KoreaM.ChoiJ.H.KimI.C.ParkS.ParkG.RyuM.S.RyuUniversity of Seoul, Seoul, Republic of KoreaUniversity of SeoulSeoulRepublic of KoreaY.ChoiY.K.ChoiJ.GohE.KwonJ.LeeH.SeoI.YuSungkyunkwan University, Suwon, Republic of KoreaSungkyunkwan UniversitySuwonRepublic of KoreaA.JuodagalvisVilnius University, Vilnius, LithuaniaVilnius UniversityVilniusLithuaniaJ.R.KomaragiriNational Centre for Particle Physics, Universiti Malaya, Kuala Lumpur, MalaysiaNational Centre for Particle PhysicsUniversiti MalayaKuala LumpurMalaysiaH.Castilla-ValdezE.De La Cruz-BureloI.Heredia-de La Cruz30R.Lopez-FernandezA.Sanchez-HernandezCentro de Investigacion y de Estudios Avanzados del IPN, Mexico City, MexicoCentro de Investigacion y de Estudios Avanzados del IPNMexico CityMexico30Also at Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Mexico.S.Carrillo MorenoF.Vazquez ValenciaUniversidad Iberoamericana, Mexico City, MexicoUniversidad IberoamericanaMexico CityMexicoI.PedrazaH.A.Salazar IbarguenBenemerita Universidad Autonoma de Puebla, Puebla, MexicoBenemerita Universidad Autonoma de PueblaPueblaMexicoE.Casimiro LinaresA.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.ButlerS.ReucroftUniversity of Canterbury, Christchurch, New ZealandUniversity of CanterburyChristchurchNew ZealandA.AhmadM.AhmadQ.HassanH.R.HooraniS.KhalidW.A.KhanT.KhurshidM.A.ShahM.ShoaibNational 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 ResearchSwierkPolandG.BronaK.BunkowskiM.CwiokW.DominikK.DorobaA.KalinowskiM.KoneckiJ.KrolikowskiM.MisiuraM.OlszewskiW.WolszczakInstitute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, PolandInstitute of Experimental PhysicsFaculty of PhysicsUniversity of WarsawWarsawPolandP.BargassaC.Beirão Da Cruz E SilvaP.FaccioliP.G.Ferreira ParrachoM.GallinaroF.NguyenJ.Rodrigues AntunesJ.SeixasJ.VarelaP.VischiaLaboratório de Instrumentação e Física Experimental de Partículas, Lisboa, PortugalLaboratório de Instrumentação e Física Experimental de PartículasLisboaPortugalI.GolutvinV.KarjavinV.KonoplyanikovV.KorenkovG.KozlovA.LanevA.MalakhovV.Matveev31V.V.MitsynP.MoisenzV.PalichikV.PerelyginS.ShmatovS.ShulhaN.SkatchkovV.SmirnovE.TikhonenkoA.ZarubinJoint Institute for Nuclear Research, Dubna, RussiaJoint Institute for Nuclear ResearchDubnaRussia31Also at Institute for Nuclear Research, Moscow, Russia.V.GolovtsovY.IvanovV.Kim32P.LevchenkoV.MurzinV.OreshkinI.SmirnovV.SulimovL.UvarovS.VavilovA.VorobyevAn.VorobyevPetersburg Nuclear Physics Institute, Gatchina (St. Petersburg), RussiaPetersburg Nuclear Physics InstituteGatchina (St. Petersburg)Russia32Also at St. Petersburg State Polytechnical University, St. Petersburg, Russia.Yu.AndreevA.DermenevS.GninenkoN.GolubevM.KirsanovN.KrasnikovA.PashenkovD.TlisovA.ToropinInstitute for Nuclear Research, Moscow, RussiaInstitute for Nuclear ResearchMoscowRussiaV.EpshteynV.GavrilovN.LychkovskayaV.PopovG.SafronovS.SemenovA.SpiridonovV.StolinE.VlasovA.ZhokinInstitute for Theoretical and Experimental Physics, Moscow, RussiaInstitute for Theoretical and Experimental PhysicsMoscowRussiaV.AndreevM.AzarkinI.DreminM.KirakosyanA.LeonidovG.MesyatsS.V.RusakovA.VinogradovP.N. Lebedev Physical Institute, Moscow, RussiaP.N. Lebedev Physical InstituteMoscowRussiaA.BelyaevE.BoosV.BunichevM.Dubinin7L.DudkoA.ErshovV.KlyukhinO.KodolovaI.LokhtinS.ObraztsovS.PetrushankoV.SavrinA.SnigirevSkobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, RussiaSkobeltsyn Institute of Nuclear PhysicsLomonosov Moscow State UniversityMoscowRussiaI.AzhgireyI.BayshevS.BitioukovV.KachanovA.KalininD.KonstantinovV.KrychkineV.PetrovR.RyutinA.SobolL.TourtchanovitchS.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.Adzic33M.DordevicM.EkmedzicJ.MilosevicUniversity of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, SerbiaUniversity of BelgradeFaculty of PhysicsVinca Institute of Nuclear SciencesBelgradeSerbia33Also at Faculty of Physics, University of Belgrade, Belgrade, Serbia.J.Alcaraz MaestreC.BattilanaE.CalvoM.CerradaM.Chamizo Llatas2N.ColinoB.De La CruzA.Delgado PerisD.Domínguez VázquezA.Escalante Del ValleC.Fernandez BedoyaJ.P.Fernández RamosJ.FlixM.C.FouzP.Garcia-AbiaO.Gonzalez LopezS.Goy LopezJ.M.HernandezM.I.JosaG.MerinoE.Navarro De MartinoA.Pérez-Calero YzquierdoJ.Puerta PelayoA.Quintario OlmedaI.RedondoL.RomeroM.S.SoaresCentro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, SpainCentro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT)MadridSpainC.AlbajarJ.F.de TrocónizM.MissiroliUniversidad Autónoma de Madrid, Madrid, SpainUniversidad Autónoma de MadridMadridSpainH.BrunJ.CuevasJ.Fernandez MenendezS.FolguerasI.Gonzalez CaballeroL.Lloret IglesiasUniversidad de Oviedo, Oviedo, SpainUniversidad de OviedoOviedoSpainJ.A.Brochero CifuentesI.J.CabrilloA.CalderonJ.Duarte CampderrosM.FernandezG.GomezA.GrazianoA.Lopez VirtoJ.MarcoR.MarcoC.Martinez RiveroF.MatorrasF.J.Munoz SanchezJ.Piedra GomezT.RodrigoA.Y.Rodríguez-MarreroA.Ruiz-JimenoL.ScodellaroI.VilaR.Vilar CortabitarteInstituto de Física de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, SpainInstituto de Física de Cantabria (IFCA)CSIC-Universidad de CantabriaSantanderSpainD.AbbaneoE.AuffrayG.AuzingerM.BachtisP.BaillonA.H.BallD.BarneyA.BenagliaJ.BendavidL.BenhabibJ.F.BenitezC.Bernet8G.BianchiP.BlochA.BocciA.BonatoO.BonduC.BottaH.BreukerT.CamporesiG.CerminaraT.ChristiansenS.Colafranceschi34M.D'AlfonsoD.d'EnterriaA.DabrowskiA.DavidF.De GuioA.De RoeckS.De VisscherM.DobsonN.Dupont-SagorinA.Elliott-PeisertJ.EugsterG.FranzoniW.FunkM.GiffelsD.GigiK.GillD.GiordanoM.GironeF.GlegeR.GuidaS.GundackerM.GuthoffJ.HammerM.HansenP.HarrisJ.HegemanV.InnocenteP.JanotK.KousourisK.KrajczarP.LecoqC.LourençoN.MaginiL.MalgeriM.MannelliL.MasettiF.MeijersS.MersiE.MeschiF.MoortgatS.MorovicM.MuldersP.MusellaL.OrsiniL.PapeE.PerezL.PerrozziA.PetrilliG.PetruccianiA.PfeifferM.PieriniM.PimiäD.PiparoM.PlaggeA.RaczG.Rolandi35M.RovereH.SakulinC.SchäferC.SchwickS.SekmenA.SharmaP.SiegristP.SilvaM.SimonP.Sphicas36D.SpigaJ.SteggemannB.StiegerM.StoyeD.TreilleA.TsirouG.I.Veres19J.R.VlimantN.WardleH.K.WöhriW.D.ZeunerCERN, European Organization for Nuclear Research, Geneva, SwitzerlandCERNEuropean Organization for Nuclear ResearchGenevaSwitzerland34Also at Facoltà Ingegneria, Università di Roma, Roma, Italy.35Also at Scuola Normale e Sezione dell'INFN, Pisa, Italy.36Also at University of Athens, Athens, Greece.W.BertlK.DeitersW.ErdmannR.HorisbergerQ.IngramH.C.KaestliS.KönigD.KotlinskiU.LangeneggerD.RenkerT.RohePaul Scherrer Institut, Villigen, SwitzerlandPaul Scherrer InstitutVilligenSwitzerlandF.BachmairL.BäniL.BianchiniP.BortignonM.A.BuchmannB.CasalN.ChanonA.DeisherG.DissertoriM.DittmarM.DonegàM.DünserP.EllerC.GrabD.HitsW.LustermannB.ManganoA.C.MariniP.Martinez Ruiz del ArbolD.MeisterN.MohrC.Nägeli37P.NefF.Nessi-TedaldiF.PandolfiF.PaussM.PeruzziM.QuittnatL.RebaneF.J.RongaM.RossiniA.Starodumov38M.TakahashiK.TheofilatosR.WallnyH.A.WeberInstitute for Particle Physics, ETH Zurich, Zurich, SwitzerlandInstitute for Particle PhysicsETH ZurichZurichSwitzerland37Also at Paul Scherrer Institut, Villigen, Switzerland.38Also at Institute for Theoretical and Experimental Physics, Moscow, Russia.C.Amsler39M.F.CanelliV.ChiochiaA.De CosaA.HinzmannT.HreusM.Ivova RikovaB.KilminsterB.Millan MejiasJ.NgadiubaP.RobmannH.SnoekS.TaroniM.VerzettiY.YangUniversität Zürich, Zurich, SwitzerlandUniversität ZürichZurichSwitzerland39Also at Albert Einstein Center for Fundamental Physics, Bern, Switzerland.M.CardaciK.H.ChenC.FerroC.M.KuoW.LinY.J.LuR.VolpeS.S.YuNational Central University, Chung-Li, TaiwanNational Central UniversityChung-LiTaiwanP.ChangY.H.ChangY.W.ChangY.ChaoK.F.ChenP.H.ChenC.DietzU.GrundlerW.-S.HouK.Y.KaoY.J.LeiY.F.LiuR.-S.LuD.MajumderE.PetrakouX.ShiY.M.TzengR.WilkenNational Taiwan University (NTU), Taipei, TaiwanNational Taiwan University (NTU)TaipeiTaiwanB.AsavapibhopN.SrimanobhasN.SuwonjandeeChulalongkorn University, Bangkok, ThailandChulalongkorn UniversityBangkokThailandA.AdiguzelM.N.Bakirci40S.Cerci41C.DozenI.DumanogluE.EskutS.GirgisG.GokbulutE.GurpinarI.HosE.E.KangalA.Kayis TopaksuG.Onengut42K.OzdemirS.Ozturk40A.PolatozK.Sogut43D.Sunar Cerci41B.Tali41H.Topakli40M.VergiliCukurova University, Adana, TurkeyCukurova UniversityAdanaTurkey40Also at Gaziosmanpasa University, Tokat, Turkey.41Also at Adiyaman University, Adiyaman, Turkey.42Also at Cag University, Mersin, Turkey.43Also at Mersin University, Mersin, Turkey.I.V.AkinB.BilinS.BilmisH.GamsizkanG.Karapinar44K.OcalanU.E.SuratM.YalvacM.ZeyrekMiddle East Technical University, Physics Department, Ankara, TurkeyMiddle East Technical UniversityPhysics DepartmentAnkaraTurkey44Also at Izmir Institute of Technology, Izmir, Turkey.E.GülmezB.Isildak45M.Kaya46O.Kaya46Bogazici University, Istanbul, TurkeyBogazici UniversityIstanbulTurkey45Also at Ozyegin University, Istanbul, Turkey.46Also at Kafkas University, Kars, Turkey.H.Bahtiyar47E.BarlasK.CankocakF.I.VardarlıM.YücelIstanbul Technical University, Istanbul, TurkeyIstanbul Technical UniversityIstanbulTurkey47Also at Mimar Sinan University, Istanbul, Istanbul, Turkey.L.LevchukP.SorokinNational Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, UkraineNational Scientific CenterKharkov Institute of Physics and TechnologyKharkovUkraineJ.J.BrookeE.ClementD.CussansH.FlacherR.FrazierJ.GoldsteinM.GrimesG.P.HeathH.F.HeathJ.JacobL.KreczkoC.LucasZ.MengD.M.Newbold48S.ParamesvaranA.PollS.SenkinV.J.SmithT.WilliamsUniversity of Bristol, Bristol, United KingdomUniversity of BristolBristolUnited Kingdom48Also at Rutherford Appleton Laboratory, Didcot, United Kingdom.K.W.BellA.Belyaev49C.BrewR.M.BrownD.J.A.CockerillJ.A.CoughlanK.HarderS.HarperE.OlaiyaD.PetytC.H.Shepherd-ThemistocleousA.TheaI.R.TomalinW.J.WomersleyS.D.WormRutherford Appleton Laboratory, Didcot, United KingdomRutherford Appleton LaboratoryDidcotUnited Kingdom49Also at School of Physics and Astronomy, University of Southampton, Southampton, United Kingdom.M.BaberR.BainbridgeO.BuchmullerD.BurtonD.CollingN.CrippsM.CutajarP.DaunceyG.DaviesM.Della NegraP.DunneW.FergusonJ.FulcherD.FutyanA.GilbertG.HallG.IlesM.JarvisG.KarapostoliM.KenzieR.LaneR.Lucas48L.LyonsA.-M.MagnanS.MalikJ.MarroucheB.MathiasJ.NashA.Nikitenko38J.PelaM.PesaresiK.PetridisD.M.RaymondS.RogersonA.RoseC.SeezP.Sharp†A.TapperM.Vazquez AcostaT.VirdeeImperial College, London, United KingdomImperial CollegeLondonUnited Kingdom†Deceased.J.E.ColeP.R.HobsonA.KhanP.KyberdD.LeggatD.LeslieW.MartinI.D.ReidP.SymondsL.TeodorescuM.TurnerBrunel University, Uxbridge, United KingdomBrunel UniversityUxbridgeUnited KingdomJ.DittmannK.HatakeyamaA.KasmiH.LiuT.ScarboroughBaylor University, Waco, USABaylor UniversityWacoUSAO.CharafS.I.CooperC.HendersonP.RumerioThe University of Alabama, Tuscaloosa, USAThe University of AlabamaTuscaloosaUSAA.AvetisyanT.BoseC.FantasiaA.HeisterP.LawsonC.RichardsonJ.RohlfD.SperkaJ.St. JohnL.SulakBoston University, Boston, USABoston UniversityBostonUSAJ.AlimenaS.BhattacharyaG.ChristopherD.CuttsZ.DemiragliA.FerapontovA.GarabedianU.HeintzS.JabeenG.KukartsevE.LairdG.LandsbergM.LukM.NarainM.SegalaT.SinthuprasithT.SpeerJ.SwansonBrown University, Providence, USABrown UniversityProvidenceUSAR.BreedonG.BretoM.Calderon De La Barca SanchezS.ChauhanM.ChertokJ.ConwayR.ConwayP.T.CoxR.ErbacherM.GardnerW.KoR.LanderT.MiceliM.MulhearnD.PellettJ.PilotF.Ricci-TamM.SearleS.ShalhoutJ.SmithM.SquiresD.StolpM.TripathiS.WilburR.YohayUniversity of California, Davis, Davis, USAUniversity of California, DavisDavisUSAR.CousinsP.EveraertsC.FarrellJ.HauserM.IgnatenkoG.RaknessE.TakasugiV.ValuevM.WeberUniversity of California, Los Angeles, USAUniversity of CaliforniaLos AngelesUSAJ.BabbR.ClareJ.EllisonJ.W.GaryG.HansonJ.HeilmanP.JandirE.KennedyF.LacroixH.LiuO.R.LongA.LuthraM.MalbertiH.NguyenA.ShrinivasJ.SturdyS.SumowidagdoS.WimpennyUniversity of California, Riverside, Riverside, USAUniversity of California, RiversideRiversideUSAW.AndrewsJ.G.BransonG.B.CeratiS.CittolinR.T.D'AgnoloD.EvansA.HolznerR.KelleyM.LebourgeoisJ.LettsI.MacneillD.OlivitoS.PadhiC.PalmerM.PieriM.SaniV.SharmaS.SimonE.SudanoM.TadelY.TuA.VartakF.WürthweinA.YagilJ.YooUniversity of California, San Diego, La Jolla, USAUniversity of California, San DiegoLa JollaUSAD.BargeJ.Bradmiller-FeldC.CampagnariT.DanielsonA.DishawK.FlowersM.Franco SevillaP.GeffertC.GeorgeF.GolfJ.IncandelaC.JustusN.MccollJ.RichmanD.StuartW.ToC.WestUniversity of California, Santa Barbara, Santa Barbara, USAUniversity of California, Santa BarbaraSanta BarbaraUSAA.ApresyanA.BornheimJ.BunnY.ChenE.Di MarcoJ.DuarteA.MottH.B.NewmanC.PenaC.RoganM.SpiropuluV.TimciucR.WilkinsonS.XieR.Y.ZhuCalifornia Institute of Technology, Pasadena, USACalifornia Institute of TechnologyPasadenaUSAV.AzzoliniA.CalambaR.CarrollT.FergusonY.IiyamaM.PauliniJ.RussH.VogelI.VorobievCarnegie Mellon University, Pittsburgh, USACarnegie Mellon UniversityPittsburghUSAJ.P.CumalatB.R.DrellW.T.FordA.GazE.Luiggi LopezU.NauenbergJ.G.SmithK.StensonK.A.UlmerS.R.WagnerUniversity of Colorado at Boulder, Boulder, USAUniversity of Colorado at BoulderBoulderUSAJ.AlexanderA.ChatterjeeJ.ChuS.DittmerN.EggertW.HopkinsB.KreisN.MirmanG.Nicolas KaufmanJ.R.PattersonA.RydE.SalvatiL.SkinnariW.SunW.D.TeoJ.ThomJ.ThompsonJ.TuckerY.WengL.WinstromP.WittichCornell University, Ithaca, USACornell UniversityIthacaUSAD.WinnFairfield University, Fairfield, USAFairfield UniversityFairfieldUSAS.AbdullinM.AlbrowJ.AndersonG.ApollinariL.A.T.BauerdickA.BeretvasJ.BerryhillP.C.BhatK.BurkettJ.N.ButlerH.W.K.CheungF.ChlebanaS.CihangirV.D.ElviraI.FiskJ.FreemanE.GottschalkL.GrayD.GreenS.GrünendahlO.GutscheJ.HanlonD.HareR.M.HarrisJ.HirschauerB.HoobermanS.JindarianiM.JohnsonU.JoshiK.KaadzeB.KlimaS.KwanJ.LinacreD.LincolnR.LiptonT.LiuJ.LykkenK.MaeshimaJ.M.MarraffinoV.I.Martinez OutschoornS.MaruyamaD.MasonP.McBrideK.MishraS.MrennaY.Musienko31S.NahnC.Newman-HolmesV.O'DellO.ProkofyevE.Sexton-KennedyS.SharmaA.SohaW.J.SpaldingL.SpiegelL.TaylorS.TkaczykN.V.TranL.UpleggerE.W.VaanderingR.VidalA.WhitbeckJ.WhitmoreF.YangFermi National Accelerator Laboratory, Batavia, USAFermi National Accelerator LaboratoryBataviaUSAD.AcostaP.AveryD.BourilkovM.CarverT.ChengD.CurryS.DasM.De GruttolaG.P.Di GiovanniR.D.FieldM.FisherI.K.FuricJ.HugonJ.KonigsbergA.KorytovT.KypreosJ.F.LowK.MatchevP.Milenovic50G.MitselmakherL.MunizA.RinkeviciusL.ShchutskaN.SkhirtladzeM.SnowballJ.YeltonM.ZakariaUniversity of Florida, Gainesville, USAUniversity of FloridaGainesvilleUSA50Also at University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia.V.GaultneyS.HewamanageS.LinnP.MarkowitzG.MartinezJ.L.RodriguezFlorida International University, Miami, USAFlorida International UniversityMiamiUSAT.AdamsA.AskewJ.BochenekB.DiamondJ.HaasS.HagopianV.HagopianK.F.JohnsonH.ProsperV.VeeraraghavanM.WeinbergFlorida State University, Tallahassee, USAFlorida State UniversityTallahasseeUSAM.M.BaarmandM.HohlmannH.KalakhetyF.YumicevaFlorida Institute of Technology, Melbourne, USAFlorida Institute of TechnologyMelbourneUSAM.R.AdamsL.ApanasevichV.E.BazterraD.BerryR.R.BettsI.BucinskaiteR.CavanaughO.EvdokimovL.GauthierC.E.GerberD.J.HofmanS.KhalatyanP.KurtD.H.MoonC.O'BrienC.SilkworthP.TurnerN.VarelasUniversity of Illinois at Chicago (UIC), Chicago, USAUniversity of Illinois at Chicago (UIC)ChicagoUSAE.A.Albayrak47B.Bilki51W.ClaridaK.DilsizF.DuruM.HaytmyradovJ.-P.MerloH.Mermerkaya52A.MestvirishviliA.MoellerJ.NachtmanH.OgulY.OnelF.Ozok47A.PenzoR.RahmatS.SenP.TanE.TirasJ.WetzelT.Yetkin53K.YiThe University of Iowa, Iowa City, USAThe University of IowaIowa CityUSA51Also at Argonne National Laboratory, Argonne, USA.52Also at Erzincan University, Erzincan, Turkey.53Also at Yildiz Technical University, Istanbul, Turkey.B.A.BarnettB.BlumenfeldS.BolognesiD.FehlingA.V.GritsanP.MaksimovicC.MartinM.SwartzJohns Hopkins University, Baltimore, USAJohns Hopkins UniversityBaltimoreUSAP.BaringerA.BeanG.BenelliC.BrunerJ.GrayR.P.Kenny IIIM.MurrayD.NoonanS.SandersJ.SekaricR.StringerQ.WangJ.S.WoodThe University of Kansas, Lawrence, USAThe University of KansasLawrenceUSAA.F.BarfussI.ChakaberiaA.IvanovS.KhalilM.MakouskiY.MaravinL.K.SainiS.ShresthaI.SvintradzeKansas State University, Manhattan, USAKansas State UniversityManhattanUSAJ.GronbergD.LangeF.RebassooD.WrightLawrence Livermore National Laboratory, Livermore, USALawrence Livermore National LaboratoryLivermoreUSAA.BadenB.CalvertS.C.EnoJ.A.GomezN.J.HadleyR.G.KelloggT.KolbergY.LuM.MarionneauA.C.MignereyK.PedroA.SkujaM.B.TonjesS.C.TonwarUniversity of Maryland, College Park, USAUniversity of MarylandCollege ParkUSAA.ApyanR.BarbieriG.BauerW.BuszaI.A.CaliM.ChanL.Di MatteoV.DuttaG.Gomez CeballosM.GoncharovD.GulhanM.KluteY.S.LaiY.-J.LeeA.LevinP.D.LuckeyT.MaC.PausD.RalphC.RolandG.RolandG.S.F.StephansF.StöckliK.SumorokD.VelicanuJ.VeverkaB.WyslouchM.YangM.ZanettiV.ZhukovaMassachusetts Institute of Technology, Cambridge, USAMassachusetts Institute of TechnologyCambridgeUSAB.DahmesA.De BenedettiA.GudeS.C.KaoK.KlapoetkeY.KubotaJ.MansN.PastikaR.RusackA.SingovskyN.TambeJ.TurkewitzUniversity of Minnesota, Minneapolis, USAUniversity of MinnesotaMinneapolisUSAJ.G.AcostaS.OliverosUniversity of Mississippi, Oxford, USAUniversity of MississippiOxfordUSAE.AvdeevaK.BloomS.BoseD.R.ClaesA.DominguezR.Gonzalez SuarezJ.KellerD.KnowltonI.KravchenkoJ.Lazo-FloresS.MalikF.MeierG.R.SnowUniversity of Nebraska-Lincoln, Lincoln, USAUniversity of Nebraska-LincolnLincolnUSAJ.DolenA.GodshalkI.IashviliA.KharchilavaA.KumarS.RappoccioState University of New York at Buffalo, Buffalo, USAState University of New York at BuffaloBuffaloUSAG.AlversonE.BarberisD.BaumgartelM.ChascoJ.HaleyA.MassironiD.M.MorseD.NashT.OrimotoD.TrocinoD.WoodJ.ZhangNortheastern University, Boston, USANortheastern UniversityBostonUSAK.A.HahnA.KubikN.MuciaN.OdellB.PollackA.PozdnyakovM.SchmittS.StoynevK.SungM.VelascoS.WonNorthwestern University, Evanston, USANorthwestern UniversityEvanstonUSAA.BrinkerhoffK.M.ChanA.DrozdetskiyM.HildrethC.JessopD.J.KarmgardN.KellamsK.LannonW.LuoS.LynchN.MarinelliT.PearsonM.PlanerR.RuchtiN.VallsM.WayneM.WolfA.WoodardUniversity of Notre Dame, Notre Dame, USAUniversity of Notre DameNotre DameUSAL.AntonelliJ.BrinsonB.BylsmaL.S.DurkinS.FlowersC.HillR.HughesK.KotovT.Y.LingD.PuighM.RodenburgG.SmithC.VuosaloB.L.WinerH.WolfeH.W.WulsinThe Ohio State University, Columbus, USAThe Ohio State UniversityColumbusUSAE.BerryO.DrigaP.ElmerP.HebdaA.HuntS.A.KoayP.LujanD.MarlowT.MedvedevaM.MooneyJ.OlsenP.PirouéX.QuanH.SakaD.Stickland2C.TullyJ.S.WernerS.C.ZenzA.ZuranskiPrinceton University, Princeton, USAPrinceton UniversityPrincetonUSAE.BrownsonH.MendezJ.E.Ramirez VargasUniversity of Puerto Rico, Mayaguez, USAUniversity of Puerto RicoMayaguezUSAE.AlagozV.E.BarnesD.BenedettiG.BollaD.BortolettoM.De MattiaA.EverettZ.HuM.K.JhaM.JonesK.JungM.KressN.LeonardoD.Lopes PegnaV.MaroussovP.MerkelD.H.MillerN.NeumeisterB.C.Radburn-SmithI.ShipseyD.SilversA.SvyatkovskiyF.WangW.XieL.XuH.D.YooJ.ZablockiY.ZhengPurdue University, West Lafayette, USAPurdue UniversityWest LafayetteUSAN.ParasharJ.StupakPurdue University Calumet, Hammond, USAPurdue University CalumetHammondUSAA.AdairB.AkgunK.M.EcklundF.J.M.GeurtsW.LiB.MichlinB.P.PadleyR.RedjimiJ.RobertsJ.ZabelRice University, Houston, USARice UniversityHoustonUSAB.BetchartA.BodekR.CovarelliP.de BarbaroR.DeminaY.EshaqT.FerbelA.Garcia-BellidoP.GoldenzweigJ.HanA.HarelA.KhukhunaishviliD.C.MinerG.PetrilloD.VishnevskiyUniversity of Rochester, Rochester, USAUniversity of RochesterRochesterUSAR.CiesielskiL.DemortierK.GoulianosG.LunguC.MesropianThe Rockefeller University, New York, USAThe Rockefeller UniversityNew YorkUSAS.AroraA.BarkerJ.P.ChouC.Contreras-CampanaE.Contreras-CampanaD.DugganD.FerencekY.GershteinR.GrayE.HalkiadakisD.HidasA.LathS.PanwalkarM.ParkR.PatelV.RekovicS.SalurS.SchnetzerC.SeitzS.SomalwarR.StoneS.ThomasP.ThomassenM.WalkerRutgers, The State University of New Jersey, Piscataway, USARutgers, The State University of New JerseyPiscatawayUSAK.RoseS.SpanierA.YorkUniversity of Tennessee, Knoxville, USAUniversity of TennesseeKnoxvilleUSAO.Bouhali54R.EusebiW.FlanaganJ.GilmoreT.Kamon55V.KhotilovichV.KrutelyovR.MontalvoI.OsipenkovY.PakhotinA.PerloffJ.RoeA.RoseA.SafonovT.SakumaI.SuarezA.TatarinovTexas A&M University, College Station, USATexas A&M UniversityCollege StationUSA54Also at Texas A&M University at Qatar, Doha, Qatar.55Also at Kyungpook National University, Daegu, Republic of Korea.N.AkchurinC.CowdenJ.DamgovC.DragoiuP.R.DuderoJ.FaulknerK.KovitanggoonS.KunoriS.W.LeeT.LibeiroI.VolobouevTexas Tech University, Lubbock, USATexas Tech UniversityLubbockUSAE.AppeltA.G.DelannoyS.GreeneA.GurrolaW.JohnsC.MaguireY.MaoA.MeloM.SharmaP.SheldonB.SnookS.TuoJ.VelkovskaVanderbilt University, Nashville, USAVanderbilt UniversityNashvilleUSAM.W.ArentonS.BoutleB.CoxB.FrancisJ.GoodellR.HiroskyA.LedovskoyH.LiC.LinC.NeuJ.WoodUniversity of Virginia, Charlottesville, USAUniversity of VirginiaCharlottesvilleUSAS.GollapinniR.HarrP.E.KarchinC.Kottachchi Kankanamge DonP.LamichhaneWayne State University, Detroit, USAWayne State UniversityDetroitUSAD.A.BelknapD.CarlsmithM.CepedaS.DasuS.DuricE.FriisR.Hall-WiltonM.HerndonA.HervéP.KlabbersJ.KlukasA.LanaroC.LazaridisA.LevineR.LovelessA.MohapatraI.OjalvoT.PerryG.A.PierroG.PoleseI.RossT.SarangiA.SavinW.H.SmithN.WoodsUniversity of Wisconsin, Madison, USAUniversity of WisconsinMadisonUSACERN, SwitzerlandCERNSwitzerland⋆E-mail address: cms-publication-committee-chair@cern.ch.Editor: M. DoserAbstractA measurement of the inclusive ZZ production cross section and constraints on anomalous triple gauge couplings in proton–proton collisions at s=8 TeV are presented. The analysis is based on a data sample, corresponding to an integrated luminosity of 19.6 fb−1, collected with the CMS experiment at the LHC. The measurements are performed in the leptonic decay modes ZZ→ℓℓℓ′ℓ′, where ℓ=e,μ and ℓ′=e,μ,τ. The measured total cross section σ(pp→ZZ)=7.7±0.5 (stat)−0.4+0.5 (syst)±0.4(theo)±0.2 (lumi) pb, for both Z bosons produced in the mass range 60<mZ<120 GeV, is consistent with standard model predictions. Differential cross sections are measured and well described by the theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZγ couplings at the 95% confidence level: −0.004<f4Z<0.004, −0.004<f5Z<0.004, −0.005<f4γ<0.005, and −0.005<f5γ<0.005.KeywordsCMSPhysicsElectroweak1IntroductionThe study of diboson production in proton–proton collisions provides an important test of the electroweak sector of the standard model (SM), especially the non-Abelian structure of the SM Lagrangian. In the SM, ZZ production proceeds mainly through quark–antiquark t- and u-channel scattering diagrams. At high-order calculations in QCD, gluon–gluon fusion also contributes via box diagrams with quark loops. There are no tree-level contributions to ZZ production from triple gauge boson vertices in the SM. Anomalous triple gauge couplings (ATGC) ZZZ and ZZγ are introduced using an effective Lagrangian following Ref. [1]. In this parametrization, two ZZZ and two ZZγ couplings are allowed by electromagnetic gauge invariance and Lorentz invariance for on-shell Z bosons and are parametrized by two CP-violating (f4V) and two CP-conserving (f5V) parameters, where V=(Z,γ). Nonzero ATGC values could be induced by new physics models such as supersymmetry [2].Previous measurements of the inclusive ZZ cross section by the CMS Collaboration at the LHC were performed in the ZZ→ℓℓℓ′ℓ′ decay channels, where ℓ=e,μ and ℓ′=e,μ,τ, with the data corresponding to an integrated luminosity of 5.1(5.0) fb−1 at s=7(8) TeV [3,4]. The measured total cross section, σ(pp→ZZ), is 6.24−0.80+0.86 (stat)−0.32+0.41 (syst)±0.14 (lumi) pb at s=7 TeV and 8.4±1.0 (stat)±0.7 (syst)±0.4 (lumi) pb at s=8 TeV for both Z bosons in the mass range 60<mZ<120 GeV. The ATLAS Collaboration measured a total cross section of 6.7±0.7 (stat)−0.3+0.4 (syst)±0.3 (lumi) pb [5] using ZZ→ℓℓℓℓ and ZZ→ℓℓνν final states with a data sample corresponding to an integrated luminosity of 4.6 fb−1 at s=7 TeV and 66<mZ<116 GeV. Measurements of the ZZ cross sections performed at the Tevatron are summarized in Refs. [6,7]. All measurements are found to agree with the corresponding SM predictions.Limits on ZZZ and ZZγ ATGCs were set by CMS using the 7 TeV data sample: −0.011<f4Z<0.012, −0.012<f5Z<0.012, −0.013<f4γ<0.015, and −0.014<f5γ<0.014 at 95% confidence level (CL) [3]. Similar limits were obtained by ATLAS [5].In this analysis, which is based on the full 2012 data set and corresponds to an integrated luminosity of 19.6 fb−1, results are presented for the ZZ inclusive and differential cross sections as well as limits for the ZZZ and ZZγ ATGCs. The cross sections are measured for both Z bosons in the mass range 60<mZ<120 GeV; contributions from virtual photon exchange are included.2The CMS detector and simulationThe CMS detector is described in detail elsewhere [8]; the key components for this analysis are summarized here. The CMS experiment uses a right-handed coordinate system, with the origin at the nominal interaction point, the x axis pointing to the center of the LHC ring, the y axis pointing up (perpendicular to the plane of the LHC ring), and the z axis along the counterclockwise-beam direction. The polar angle θ is measured from the positive z axis and the azimuthal angle ϕ is measured in the x–y plane. The magnitude of the transverse momentum is pT=px2+py2. A superconducting solenoid is located in the central region of the CMS detector, providing an axial magnetic field of 3.8T parallel to the beam direction. A silicon pixel and strip tracker, a crystal electromagnetic calorimeter (ECAL), and a brass and scintillator hadron calorimeter are located within the solenoid and cover the absolute pseudorapidity range |η|<3.0, where pseudorapidity is defined as η=−ln⁡[tan⁡(θ/2)]. The ECAL barrel region (EB) covers |η|<1.479 and two endcap regions (EE) cover 1.479<|η|<3.0. A quartz-fiber Cherenkov calorimeter extends the coverage up to |η|<5.0. Gas ionization muon detectors are embedded in the steel flux-return yoke outside the solenoid. A first level of the CMS trigger system, composed of custom hardware processors, is designed to select events of interest in less than 4 μs using information from the calorimeters and muon detectors. A high-level-trigger processor farm reduces the event rate from 100 kHz delivered by the first level trigger to a few hundred hertz.Several Monte Carlo (MC) event generators are used to simulate the signal and background contributions. The qq¯→ZZ process is generated at next-to-leading order (NLO) with powheg 2.0 [9–11] or at leading-order (LO) with sherpa [12]. The gg→ZZ process is simulated with gg2zz [13] at LO. Other diboson processes (WZ, Zγ) and the Z+jets samples are generated at LO with MadGraph 5 [14]. Events from tt¯ production are generated at NLO with powheg. The pythia 6.4 [15] package is used for parton showering, hadronization, and the underlying event simulation. The default set of parton distribution functions (PDF) used for LO generators is CTEQ6L [16], whereas CT10 [17] is used for NLO generators. The ZZ yields from simulation are scaled according to the theoretical cross sections calculated with mcfm 6.0 [18] at NLO for qq→ZZ and at LO for gg→ZZ with the MSTW2008 PDF [19] with renormalization and factorization scales set to μR=μF=91.2 GeV. The τ-lepton decays are simulated with tauola [20]. For all processes, the detector response is simulated using a detailed description of the CMS detector based on the Geant4 package [21], and event reconstruction is performed with the same algorithms that are used for data. The simulated samples include multiple interactions per bunch crossing (pileup), such that the pileup distribution matches that of data, with an average value of about 21 interactions per bunch crossing.3Event reconstructionA complete reconstruction of the individual particles emerging from each collision event is obtained via a particle-flow (PF) technique [22,23], which uses the information from all CMS sub-detectors to identify and reconstruct individual particles in the collision event. The particles are classified into mutually exclusive categories: charged hadrons, neutral hadrons, photons, muons, and electrons.Electrons are reconstructed within the geometrical acceptance, |ηe|<2.5, and for transverse momentum pTe>7 GeV. The reconstruction combines the information from clusters of energy deposits in the ECAL and the trajectory in the tracker [24]. Particle trajectories in the tracker volume are reconstructed using a modeling of the electron energy loss and fitted with a Gaussian sum filter [25]. The contribution of the ECAL energy deposits to the electron transverse momentum measurement and its uncertainty are determined via a multivariate regression approach. Electron identification relies on a multivariate technique that combines observables sensitive to the amount of bremsstrahlung along the electron trajectory, the geometrical and momentum matching between the electron trajectory and associated clusters, as well as shower shape observables.Muons are reconstructed within |ημ|<2.4 and for pTμ>5 GeV [26]. The reconstruction combines information from both the silicon tracker and the muon detectors. The PF muons are selected from among the reconstructed muon track candidates by applying requirements on the track components in the muon system and matching with minimum ionizing particle energy deposits in the calorimeters.For τ leptons, two principal decay modes are distinguished: a leptonic mode, τℓ, with a final state including either an electron or a muon, and a hadronic mode, τh, with a final state including hadrons. The PF particles are used to reconstruct τh with the “hadron-plus-strip” algorithm [27], which optimizes the reconstruction and identification of specific τh decay modes. The π0 components of the τh decays are first reconstructed and then combined with charged hadrons to reconstruct the τh decay modes. Cases where τh includes three charged hadrons are also included. The missing transverse energy that is associated with neutrinos from τ decays is ignored in the reconstruction. The τh candidates in this analysis are required to have |ητh|<2.3 and pTτh>20 GeV.The isolation of individual electrons or muons is measured relative to their transverse momentum pTℓ, by summing over the transverse momenta of charged hadrons and neutral particles in a cone with ΔR=(Δη)2+(Δϕ)2=0.4 around the lepton direction at the interaction vertex:(1)RIsoℓ=(∑pTcharged+MAX[0,∑pTneutral+∑pTγ−ρ×Aeff])/pTℓ. The ∑pTcharged is the scalar sum of the transverse momenta of charged hadrons originating from the primary vertex. The primary vertex is chosen as the vertex with the highest sum of pT2 of its constituent tracks. The ∑pTneutral and ∑pTγ are the scalar sums of the transverse momenta for neutral hadrons and photons, respectively. The average transverse-momentum flow density ρ is calculated in each event using a “jet area” [28], where ρ is defined as the median of the pTjet/Ajet distribution for all pileup jets in the event. The effective area Aeff is the geometric area of the isolation cone times an η-dependent correction factor that accounts for the residual dependence of the isolation on pileup. Electrons and muons are considered isolated if RIsoℓ<0.4. Allowing τ leptons in the final state increases the background contamination, therefore tighter isolation requirements are imposed for electrons and muons in ZZ→ℓℓττ decays: RIsoℓ<0.25 for Z→τℓ+τℓ−, and RIsoe<0.1 for Z→τeτh, and RIsoμ<0.15 for τμτh.The isolation of the τh is calculated as the scalar sum of the transverse momenta of the charged hadrons and neutral particles in a cone of ΔR=0.5 around the τh direction reconstructed at the interaction vertex. The τh isolation includes a correction for pileup effects, which is based on the scalar sum of transverse momenta of charged particles not associated with the primary vertex in a cone of ΔR=0.8 about the τh candidate direction (pTPU). The isolation variable is defined as:(2)IPF=(∑pTcharged+MAX[0,∑pTneutral+∑pTγ−f×pTPU]), where the scale factor of f=0.0729, which is used in estimating the contribution to the isolation sum from neutral hadrons and photons, accounts for the difference in the neutral and charged contributions and in the cone sizes. Two standard working points are defined based on the value of the isolation sum corrected for the pileup contribution: IPF<1(8) GeV for final states including one (two) τh candidates.The electron and muon pairs from Z-boson decays are required to originate from the primary vertex. This is ensured by demanding that the significance of the three-dimensional impact parameter relative to the event vertex, SIP3D, satisfies SIP3D=|IPσIP|<4 for each lepton. The IP is the distance of closest approach of the lepton track to the primary vertex and σIP is its associated uncertainty.The combined efficiencies of reconstruction, identification, and isolation of primary electrons or muons are measured in data using a “tag-and-probe” technique [29] applied to an inclusive sample of Z events. The measurements are performed in bins of pTℓ and |ηℓ|. The efficiency for selecting electrons in the ECAL barrel (endcaps) is about 70% (60%) for 7<pTe<10 GeV, 85% (77%) at pTe≃10 GeV, and 95% (89%) for pTe≥20 GeV. It is about 85% in the transition region between the ECAL barrel and endcaps (1.44<|η|<1.57), averaging over the whole pT range. The muons are reconstructed and identified with an efficiency greater than ∼98% in the full |ημ|<2.4 range. The τh reconstruction efficiency is approximately 50% [27].Final-state radiation (FSR) may affect the measured four-momentum of the leptons if it is not properly included in the reconstruction. For electrons, a significant portion of the FSR photons is included in the reconstructed energy because of the size of the electromagnetic clusters, but for muons additional treatment of the FSR photons is important. All photons reconstructed within |ημ|<2.4 are considered as possible FSR candidates if they have a transverse momentum pTγ>2(4) GeV and are found within ΔR<0.07(0.07<ΔR<0.5) from the closest selected lepton candidate and are isolated. The photon isolation observable RIsoγ is the sum of the transverse momenta of charged hadrons, neutral hadrons, and photons in a cone of ΔR=0.3 around the candidate photon direction, divided by pTγ. Isolated photons must satisfy RIsoγ<1. The recovered FSR photon is included in the lepton four-momentum and the lepton isolation is then recalculated without it.The performance of the FSR selection algorithm has been determined using simulated samples, and the rate is verified with the Z and ZZ events in data. The photons within the acceptance for the FSR selection are reconstructed with an efficiency of about 50% and with a mean purity of 80%. The FSR photons are recovered in 0.5(5)% of inclusive Z events with electron (muon) pairs.4Event selectionThe data sample used in this analysis is selected by the trigger system, which requires the presence of a pair of electrons or muons, or a triplet of electrons. Triggers requiring an electron and a muon are also used. For the double-lepton triggers, the highest pT and the second-highest pT leptons are required to have pT greater than 17 and 8 GeV, respectively, while for the triple-electron trigger the thresholds are 15, 8, and 5 GeV. The trigger efficiency for ZZ events within the acceptance of this analysis is greater than 98%. The use of the triple-electron trigger with a looser pT requirement helps to recover 1–2% of the signal events, while for muons such contribution was found to be negligible.In selected ZZ events, the Z candidate with the mass closest to the Z-boson mass is denoted Z1 and the other one, Z2. The selection is designed to give mutually exclusive sets of signal candidates first selecting ZZ decays to 4e, 4μ, and 2e2μ, in the following denoted ℓℓℓ″ℓ″; these events are not considered in ZZ→ℓℓττ channel. The leptons are identified and isolated as described in Section 3. When building the Z candidates, the FSR photons are kept if |mℓℓγ−mZ|<|mℓℓ−mZ| and mℓℓγ<100 GeV. In the following, the presence of the photons in the ℓℓℓ″ℓ″ kinematics is implicit. The leptons constituting a Z candidate are required to be the same flavor and to have opposite charges (ℓ+ℓ−). The pair is retained if it satisfies 60<mZ<120 GeV. If more than one Z2 candidate satisfies all criteria, the ambiguity is resolved by choosing the pair of leptons with the highest scalar sum of pT. Among the four selected leptons forming the Z1 and the Z2, at least one should have pT>20 GeV and another one should have pT>10 GeV. These pT thresholds ensure that the selected events have leptons with pT values on the high-efficiency plateau for the trigger.For the ℓℓττ final state, events are required to have one Z1→ℓ+ℓ− candidate with pT>20 GeV for one of the leptons and pT>10 GeV for the other lepton, and a Z2→τ+τ−, with τ decaying into τe, τμ, or τh. The leptons from the τℓ decays are required to have pTℓ>10 GeV. The τh candidates are required to have pTτh>20 GeV. The FSR recovery is not applied to the ℓℓττ final states, since it does not improve the mass reconstruction. The invariant mass of the reconstructed Z1 is required to satisfy 60<mℓℓ<120 GeV, and that of the Z2 to satisfy mmin<mττ<90 GeV, where mmin=20 GeV for Z2→τeτμ final states and 30 GeV for all others.5Background estimationThe lepton identification and isolation requirements described in Section 3 significantly suppress all background contributions, and the remnant portion of them arise mainly from the Z and WZ production in association with jets, as well as tt¯. In all these cases, a jet or a non-prompt lepton is misidentified as an isolated e, μ, τh, τe, or τμ. Leptons produced in the decay of Z bosons are referred to as prompt leptons; leptons from e.g. heavy meson decays are non-prompt. The requirements to eliminate non-prompt leptons also remove hadrons that appear to be leptons.To estimate the expected number of background events in the signal region, control data samples are defined for each lepton flavor combination ℓ′ℓ′. The e and τe, and μ and τμ are considered as different flavors, since they originate from different particles.The control data samples for the background estimate are obtained by selecting events containing Z1, which passes all selection requirements, and two additional lepton candidates ℓ′ℓ′. The additional lepton pair must have opposite charge and matching flavor (e±e∓,μ±μ∓,τ±τ∓). Control data samples enriched with Z+X events, where X stands for bb¯, cc¯, gluon, or light quark jets, are obtained by requiring that both additional leptons pass only relaxed identification criteria and are required to be not isolated. By requiring one of the additional leptons to pass the full selection requirements, one obtains data samples enriched with WZ events and significant number of tt¯ events. The expected number of background events in the signal region for each flavor pair is obtained by scaling the number of observed Z1+ℓ′ℓ′ events by the lepton misidentification probability and combining the results for Z+X and WZ, tt¯ control regions together. The procedure is identical for all lepton flavors.The misidentification probability, i.e., the probability for a lepton candidate that passes the relaxed requirements to pass the full selection, is measured separately for each flavor from a sample of Z1+ℓcandidate events with a relaxed identification and no isolation requirements on the ℓcandidate. The misidentification probability for each lepton flavor is defined as the ratio of the number of leptons that pass the final isolation and identification requirements to the total number of leptons in the sample. It is measured in bins of lepton pT and η. The contamination from WZ events, which may lead to an overestimate of the misidentification probability because of the presence of genuine isolated leptons, is suppressed by requiring that the measured missing transverse energy is less than 25 GeV.The estimated background contributions to the signal region are summarized in Table 1. The procedure excludes a possible double counting due to Z+X events that can be found in the WZ control region. A correction for the small contribution of ZZ events in the control region is applied based on MC simulation. The predicted background yield has a small effect on the ZZ cross section measurement in the ℓℓℓ″ℓ″ channels, but is comparable to the signal yield for the case of ℓℓττ.6Systematic uncertaintiesThe systematic uncertainties for trigger efficiency (1.5%) are evaluated from data. The uncertainties arising from lepton identification and isolation are 1–2% for muons and electrons, and 6–7% for τh. The uncertainty in the LHC integrated luminosity of the data sample is 2.6% [30].Theoretical uncertainties in the ZZ→ℓℓℓ″ℓ″ acceptance are evaluated using mcfm and by varying the renormalization and factorization scales, up and down, by a factor of two with respect to the default values μR=μF=mZ. The variations in the acceptance are 0.1% (NLO qq¯→ZZ) and 0.4% (gg→ZZ), and can be neglected. Uncertainties related to the choice of the PDF and the strong coupling constant αs are evaluated following the PDF4LHC [31] prescription and using CT10, MSTW08, and NNPDF [32] PDF sets and found to be 4% (NLO qq¯→ZZ) and 5% (gg→ZZ).The uncertainties in Z+jets, WZ+jets, and tt¯ yields reflect the uncertainties in the measured values of the misidentification rates and the limited statistics of the control regions in the data, and vary between 20% and 70%.The uncertainty in the unfolding procedure discussed in Section 7 arises from differences between sherpa and powheg for the unfolding factors (2–3%), from scale and PDF uncertainties (4–5%), and from experimental uncertainties (4–5%).7The ZZ cross section measurementThe measured and expected event yields for all decay channels are summarized in Table 1. The recently discovered Higgs particle with the mass of 125 GeV does not contribute to this analysis as background because of the phase space selection requirements. The reconstructed four-lepton invariant mass distributions for the 4e, 4μ, 2e2μ, and combined ℓℓττ decay channels are shown in Fig. 1. The shape of the background is taken from data. The reconstructed four-lepton invariant mass distribution for the combined 4e, 4μ, and 2e2μ channels is shown in Fig. 2 (upper left). Fig. 2 (upper right) presents the invariant mass of the Z1 candidates. Figs. 2 (lower left) and (lower right) show the correlation between the reconstructed Z1 and Z2 masses for (lower left) 4e, 4μ, and 2e2μ and for (lower right) ℓℓττ final states. The data are well reproduced by the signal simulation and with background predictions estimated from data.The measured yields are used to evaluate the total ZZ production cross section. The signal acceptance is evaluated from simulation and corrected for each individual lepton flavor in bins of pT and η using factors obtained with the “tag-and-probe” technique. The requirements on pT and η for the particles in the final state reduce the full possible phase space of the ZZ→4ℓ measurement by a factor within a range of 0.56–0.59 for the 4e, 4μ, and 2e2μ, depending on the final state, and by a factor of 0.18–0.21 for the ℓℓττ final states, with respect to all events generated in the mass window 60<mZ1,mZ2<120 GeV. The branching fraction for Z→ℓ′ℓ′ is (3.3658±0.0023)% for each lepton flavor [33].To include all final states in the cross section calculation, a simultaneous fit to the number of observed events in all decay channels is performed. The likelihood is written as a combination of individual channel likelihoods for the signal and background hypotheses, with systematical uncertainties used as nuisance parameters in the fit. Each τ-lepton decay mode, listed in Table 1, is treated as a separate channel.Table 2 lists the total cross section obtained from each individual decay channel as well as the total cross section based on the combination of all channels. The measured cross section agrees with the theoretical value of 7.7±0.6 pb calculated with mcfm 6.0. In this calculation, the contribution from qq¯→ZZ is obtained at NLO, while the smaller contribution (approximately 6%) from gg→ZZ is obtained at LO. The MSTW2008 PDF is used and the renormalization and factorization scales set to μR=μF=91.2 GeV.The measurement of the differential cross sections is an important part of this analysis, since it provides detailed information about ZZ kinematics. Three decay channels, 4e, 4μ, and 2e2μ, are combined, since their kinematic distributions are the same; the ℓℓττ channel is not included. The observed yields are unfolded using the method described in Ref. [34].The differential distributions normalized to the fiducial cross sections are presented in Figs. 3 and 4 for the combination of the 4e, 4μ, and 2e2μ decay channels. The fiducial cross section definition includes pTℓ and |ηℓ| selections on each lepton, and the 60–120 GeV mass requirement, as described in Section 4. Fig. 3 shows the differential cross sections in bins of pT for: (upper left) the highest-pT lepton in the event, (upper right) the Z1, and (lower left) the ZZ system. Fig. 3 (lower left) shows the normalized dσ/dmZZ distribution. The data are corrected for background contributions and compared with the theoretical predictions from powheg and mcfm. The bottom part of each plot shows the ratio of the measured to the predicted values. The bin sizes were chosen according to the resolution of the relevant variables, trying also to keep the statistical uncertainties at a similar level for all the bins. Fig. 4 shows the angular correlations between Z bosons, which are in good agreement with the MC simulations. Some difference between powheg and mcfm calculations appears at very low pT of the ZZ system and for azimuthal separation of the Z bosons close to π. This region is better modeled by powheg interfaced with the pythia parton shower program.8Limits on anomalous triple gauge couplingsThe presence of ATGCs would be manifested as an increased yield of events at high four-lepton masses. Fig. 5 presents the distribution of the four-lepton reconstructed mass, which is used to set the limits, for the combined 4e, 4μ, and 2e2μ channels. The shaded histogram represents the results of the powheg simulation for the ZZ signal, and the dashed line, which agrees well with it, is the prediction of sherpa for f4Z=0 normalized to the mcfm cross section. The dotted line indicates the sherpa predictions for a specific ATGC value (f4Z=0.015) with all the other anomalous couplings set to zero.The invariant mass distributions are interpolated from the sherpa simulation for different values of the anomalous couplings in the range between 0 and 0.015. For each distribution, only one or two couplings are varied while all others are set to zero. The measured signal is obtained from a comparison of the data to a grid of ATGC models in the (f4Z,f4γ) and (f5Z,f5γ) parameter planes. Expected signal values are interpolated between the 2D grid points using a second-degree polynomial, since the cross section for signal depends quadratically on the coupling parameters. A profile likelihood method [33] is used to derive the limits. Systematic uncertainties are taken into account by varying the number of expected signal and background events within their uncertainties. No form factor is used when deriving the limits so that the results do not depend on any assumed energy scale characterizing new physics. The constraints on anomalous couplings are displayed in Fig. 6. The curves indicate 68% and 95% confidence levels, and the solid dot shows where the likelihood reaches its maximum. Coupling values outside the contours are excluded at the corresponding confidence levels. The limits are dominated by statistical uncertainties.One-dimensional 95% CL limits for the f4Z,γ and f5Z,γ anomalous coupling parameters are:−0.004<f4Z<0.004,−0.004<f5Z<0.004,−0.005<f4γ<0.005,−0.005<f5γ<0.005. In the one-dimensional fits, all of the ATGC parameters except the one under study are set to zero. These values extend previous CMS results on vector boson self-interactions [3] and improve on the previous limits by factors of three to four, they are presented in Fig. 6 as horizontal and vertical lines.9SummaryMeasurements have been presented of the inclusive ZZ production cross section in proton–proton collisions at 8 TeV in the ZZ→ℓℓℓ′ℓ′ decay mode, with ℓ=e,μ and ℓ′=e,μ,τ. The data sample corresponds to an integrated luminosity of 19.6 fb−1. The measured total cross section σ(pp→ZZ)=7.7±0.5 (stat)−0.4+0.5 (syst)±0.4(theo)±0.2 (lumi) pb for both Z bosons in the mass range 60<mZ<120 GeV and the differential cross sections agree well with the SM predictions. Improved limits on anomalous ZZZ and ZZγ triple gauge couplings are established, significantly restricting their possible allowed ranges.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); 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); NRF and WCU (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS and RFBR (Russia); MESTD (Serbia); SEIDI and CPAN (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).Individuals have received support from the Marie-Curie programme and the European Research Council and EPLANET (European Union); the Leventis Foundation; the A.P. 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