The Search for a Heavy Higgs Boson in the H->ZZ Decay Channels with the ATLAS Detector at the LHC

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(1)The Search for a Heavy Higgs Boson in the H->ZZ Decay Channels with the ATLAS Detector at the LHC Maria Hoffmann. To cite this version: Maria Hoffmann. The Search for a Heavy Higgs Boson in the H->ZZ Decay Channels with the ATLAS Detector at the LHC. High Energy Physics - Experiment [hep-ex]. Université Paris-Saclay, 2016. English. �NNT : 2016SACLS263�. �tel-01396919�. HAL Id: tel-01396919 https://tel.archives-ouvertes.fr/tel-01396919 Submitted on 16 Nov 2016. HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés..

(2) NNT : 2016SACLS263. THÈSE DE DOCTORAT DE. L’UNIVERSITÉ PARIS-SACLAY PRÉPARÉE À L’UNIVERSITE. PARIS-SUD. ÉCOLE DOCTORALE N° 576 Particules, Hadrons, Énergie, Noyau, Instrumentation, Imagerie, Cosmos et Simulation (PHENIICS). Spécialité de doctorat : Physique des particules Par. Mme Maria Hoffmann Recherche d’un boson de Higgs additionnel de plus haute masse via sa désintégration en une paire de bosons de jauge Z avec le détecteur ATLAS au LHC. Thèse présentée et soutenue au CEA Saclay, le 7 Octobre 2016 Composition du Jury : M. M. Mme M. Mme M. Mme. Patrick Nikolaos Chiara Michael Chiara Reisaburo Rodanthi. Puzo Konstantinidis Mariotti Duehrssen-Debling Roda Tanaka Nikolaidou. Professeur, Centre scientifique d'Orsay Professeur, University College London Professeur (contrat), INFN Docteur, CERN Professeur, Università di Pisa Chargé de recherche, Centre scientifique d'Orsay Ingénieur chercheur, CEA Saclay IRFU/SPP. Président Rapporteur Rapporteur Examinateur Examinatrice Examinateur Directrice de thèse.

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(4) JJJ. ۠*U XBT UIF TFDSFUT PG IFBWFO BOE FBSUI UIBU * EFTJSFE UP MFBSO BOE XIFUIFS JU XBT UIF PVUXBSE TVCTUBODF PG UIJOHT PS UIF JOOFS TQJSJU PG OBUVSF BOE UIF NZTUFSJPVT TPVM PG NBO UIBU PDDVQJFE NF TUJMM NZ JORVJSJFT XFSF EJSFDUFE UP UIF NFUBQIZTJDBM PS JO JUT IJHIFTU TFOTF UIF QIZTJDBM TFDSFUT PG UIF XPSME‫ڧ‬ ۗ .BSZ 4IFMMFZ 'SBOLFOTUFJO. Thèse préparée à l'Institut de recherche sur les lois fondamentales de l'Univers Service de Physique des Particules, BˆBt. 141 CEA-Saclay 91191 Gif-sur-Yvette CEDEX.

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(8) WJJ. Contents Acknowledgements. v. 1. Introduction. 1. 2. The Standard Model and Beyond. 3. 2.1. The Standard Model of Particle Physics . . . . . . . . . . . . . . . . . . . . . . . . . .. . 2.2. Electroweak Symmetry Breaking . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 2.3. Constraints on the Higgs Boson Mass . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 2.4. The Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 2.5. Production and Decay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 2.6. The Narrow Width Approximation and Interference . . . . . . . . . . . . . . . . . . .. . 2.7. Shortcomings of the Standard Model . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 2.8. The 2 Higgs Doublet Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 2.8.1. . 3. Phenomenology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Experimental Facilities. 23. 3.1. The Large Hadron Collider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.1.1. Luminosity and Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.2. The LHC Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.3. The ATLAS Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.4. The Inner Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.4.1. Semiconductor Trackers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.4.2. The Transition Radiation Tracker . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.4.3. Solenoid Magnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . Calorimeters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.5.1. Liquid Argon Calorimeters . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.5.2. Tile Calorimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . Muon Spectrometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.5. 3.6.

(9) WJJJ. 3.7 3.8. 3.6.1. Monitored Drift Tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.6.2. Cathode Strip Chambers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.6.3. Thin Gap Chambers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.6.4. Resistive Plate Chambers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.6.5. Run-2 Updates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.6.6. Toroidal Magnets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . Trigger and Data Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 3.7.1. Minimum Bias Trigger Scintillators . . . . . . . . . . . . . . . . . . . . . . . .. . ATLAS Data Processing and Simulation . . . . . . . . . . . . . . . . . . . . . . . . . .. . 4 Overview of Heavy Higgs Boson Searches. 5. 45. 4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 4.2. Author's Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . Search for an Additional, Heavy Higgs Boson in the H :ZZ :4l Decay Channel Using √s= 8 TeV Data. 47. 5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.2. The √s = 8 TeV Data-Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.3. Event Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.3.1. Triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.3.2. Object Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.3.3. Lepton Pre-Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.3.4. Di-lepton Pairing and Quadruplet Selection . . . . . . . . . . . . . . . . . . .. . 5.3.5. Double Z Mass Constraint Studies . . . . . . . . . . . . . . . . . . . . . . . .. . 5.3.6. Event Categorisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . Signal Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.4.1. The Narrow Width Approximation . . . . . . . . . . . . . . . . . . . . . . . .. . 5.4.2. Monte Carlo Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.4.3. Shape Parametrisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.4.4. Acceptance and Yield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . Background Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.5.1. Irreducible Backgrounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.5.2. Reducible Backgrounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . Systematic Uncertainties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.6.1. Experimental Uncertainties . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.6.2. Theoretical Uncertainties . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.4. 5.5. 5.6.

(10) JY 5.7. 5.8. 5.9 6. Statistical Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.7.1. Including Nuisance Parameters . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.7.2. The Fitting Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.7.3. The CLS Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.7.4. Nuisance Parameter Rankings and Pulls . . . . . . . . . . . . . . . . . . . . .. . Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.8.1. Post-fit Yields and Distributions . . . . . . . . . . . . . . . . . . . . . . . . .. . 5.8.2. Upper Limits on Heavy Higgs Boson Production Rate . . . . . . . . . . . . . . . Conclusion and Further Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Combination of Heavy Higgs Boson Searches in the H :ZZ Decay Channels Using √s = 8 TeV Data. 109. 6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2. The H :ZZ(⇤) :2l2v Decay Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3. 6.4. 6.5. 6.6. 6.7. 6.2.1. Missing Transverse Energy Reconstruction . . . . . . . . . . . . . . . . . . . . . 6.2.2. Event Categorisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.3. Backgrounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.4. Statistical Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The H :ZZ(⇤) :2l2q Decay Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.1. b-tagging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.2. Event Categorisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.3. Backgrounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.4. Statistical Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The H :ZZ(⇤) :2v2q Decay Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.1. Event Selection and Categorisation . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.2. Backgrounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.3. Statistical Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Combination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5.1. Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5.2. Correlation Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nuisance Parameter Rankings and Pulls . . . . . . . . . . . . . . . . . . . . . . . . . 6.6.1. Nuisance Parameters From the 4l and 2l2v Decay Channels . . . . . . . . . . . . 6.6.2. Nuisance Parameters From the 2l2q and 2v2q Decay Channels . . . . . . . . . . Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7.1. Upper Limits on Heavy Higgs Boson Production Rate . . . . . . . . . . . . . . .

(11) Y 6.7.2 6.8 7. 2HDM Interpretation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Search for an Additional, Heavy Higgs Boson in the H :ZZ :4l Decay Channel Using √s = 13 TeV Data. 151. 7.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2. The √s = 13 TeV Data-Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3. Monte Carlo Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4. Analysis Changes Since Run-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.1. Impact of IBL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2. Muon Reconstruction and Identification . . . . . . . . . . . . . . . . . . . . . . 7.4.3. Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.4. Optimization of Isolation and d0 Significance . . . . . . . . . . . . . . . . . . . 7.4.5. Event Categorisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.6. Signal Shape Parametrisation . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.7. Signal Acceptance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.8. Background Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.9. Systematic Uncertainties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.10 Systematic Rankings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5. 7.6 8. 7.5.1. Post-fit Yields and Distributions . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.2. Upper Limits on Heavy Higgs Boson Production Rate . . . . . . . . . . . . . . . Conclusion and Further Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusion of Heavy Higgs Boson Searches 8.1. 9. Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.1. Comparison of Combined Run-1 Results . . . . . . . . . . . . . . . . . . . . . . 8.1.2. Sensitivity Comparison of the H : ZZ(⇤) : 4l Searches . . . . . . . . . . . . . . . Characterization of Run-2 Minimum Bias Trigger Scintillators 9.1. 175. 181. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.1. Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.2. Author's Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2. Run-2 Upgrades of the MBTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3. Calibrating the Photomultiplier to One Photoelectron . . . . . . . . . . . . . . . . . . . 9.4. Cosmic Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(12) YJ 9.5. Measurement Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.6. Correcting for Light Loss in Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.7. Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.8. 9.7.1. Fiber Attenuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.7.2. MBTS Yield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Summary and Implications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Sommaire de la thése en français. 197. 10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2 Recherches dans le canal du Higgs se désintégrant en ZZ en quatre leptons, avec les données à 8 TeV. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3 Combinaison des recherches avec les données à 8 TeV . . . . . . . . . . . . . . . . . . 10.4 Recherches dans le canal du Higgs se désintégrant en ZZ en quatre leptons, avec les données à 13 TeV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5 Caractérisation des scintillateurs du déclencheur à biais minimum . . . . . . . . . . . A Auxiliary Material for the Combination of the four H : ZZ Searches. 207. B Minimum Bias Trigger Scintillators for ATLAS: Commissioning and Run-2 Initial Operation. 211. C Probing Compositeness with Higgs Boson Decays at the LHC. 213. Bibliography. 221.

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(26) YJY 3FMBUJWF UJNJOH PG UIF SJTJOH FEHF PG UIF OT USJHHFS TJHOBM GSPN UIF EJ੖FSFOU .JO JNVN #JBT 5SJHHFS 4DJOUJMMBUPS .#54 DPVOUFST JO VOJUT PG OT #VODI $SPTTJOH #$ XJUI SFTQFDU UP UIF CVODI DSPTTJOH QPTJUJPO XIFSF CFBNT XFSF DPMMJEJOH JO "5-"4. . -JNJUFT TVS. ⇥ BR(H ! Z Z (⇤) ) QPVS VO $- EF FO GPODUJPO EF m H EBOT MFT. DBU©HPSJFT " HH' FU # 7#' -B DPVSCF OPJSF FU MFT QPJOUT JOEJRVFOU MFT MJNJUFT. PCTFSW©FT -B MJHOF QPJOUJMM©F OPJSF SFQS©TFOUF MFT MJNJUFT QS©EJUFT BMPST RVF MFT CBOEFT WFSUF FU KBVOF TZNCPMJTFOU MFT E©WJBUJPOT FU TVS MB MJNJUF B॒FOEVF -JNJUFT TVQ©SJFVSFT TVS. . ⇥ #3(H ! Z Z) FO VUJMJTBOU MB N©UIPEF EFT $-4 FO. GPODUJPO EF m H PCUFOVFT QBS DPNCJOBJTPO EFT RVBUSF SFDIFSDIFT EBOT MFT DBU© HPSJFT " HH' FU # 7#' -B DPVSCF OPJSF FU MFT QPJOUT JOEJRVFOU MB MJNJUF PCTFSW©F -B DPVSCF OPJSF FO QPJOUJMM©T SFQS©TFOUF MB MJNJUF B॒FOEVF UBOEJT RVF MFT CBOEFT WFSUF FU KBVOF NBU©SJBMJTFOU MFT JODFSUJUVEFT FU TVS MB MJNJUF B॒FOEVF -FT DPVSCFT DPMPS©FT FO QPJOUJMM©T TZNCPMJTFOU MFT MJNJUFT PCUFOVFT QPVS MFT EJ੖©SFOUFT SFDIFSDIFT JOEJWJEVFMMFT $POUPVST E‫۝‬FYDMVTJPO EBOT MFT )%. EF " 5ZQF FU # 5ZQF QPVS m H = (F7 EBOT MFT FTQBDFT EF QBSBNÜSFT DPT(. ↵) FU UBO( ) -FT BJSFT SPVHFT IBDIVS©FT. NPOUSFOU MFT MJNJUFT E‫۝‬FYDMVTJPO PCFSTW©FT BWFD MFT CPSET TPVMJHO©T QBS MFT DPVSCFT SPVHFT -B DPVSCF CMFVF FO QPJOUJMM©T SFQS©TFOUF MF DPOUPVS E‫۝‬FYDMVTJPO B॒FOEV FU MFT CBOEFT WFSUF FU KBVOF MFT JODFSUJUVEFT FU TVS MB WBMFVS B॒FOEVF -‫©۝‬DIFMMF EF M‫۝‬BYF WFSUJDBM FTU DIPJTJF EF UFMMF TPSUF RVF EFT S©HJPOT QPVS MFTRVFMMFT MFT DPV QMBHFT EV CPTPO EF )JHHT M¨HFS TPOU USPJT GPJT QMVT HSBOE RVF DFVY EV .PE¨MF 4UBO EBSE TPOU FYDMVFT. . $POUPVST E‫۝‬FYDMVTJPO EBOT )%. EF " 5ZQF FU # 5ZQF QPVS $ DPT( ↵) = FU % DPT(. ↵) = FO GPODUJPO EF m H FU EF UBO( ) -‫ ۝‬BJSF SPVHF. IBDIVS©F NPOUSF MB S©HJPO E‫۝‬FYDMVTJPO PCTFSW©F -B DPVSCF CMFVF SFQS©TFOUF MF DPO UPVS E‫۝‬FYDMVTJPO B॒FOEV FU MFT CBOEFT WFSUF FU KBVOF TZNCPMJTFOU MFT JODFSUJUVEFT FU TVS DF DPOUPVS -‫۝‬BJSF HSJTF NBTRVF MFT S©HJPOT QPVS MFTRVFMMFT MB MBSHFVS EV CPTPO FTU TVQ©SJFVSF EF m H . . -JNJUFT TVQ©SJFVSFT $-4 TVS MF QSPEVJU ⇥ BR(H ! Z Z (⇤) ! `) FO GPODUJPO EF m H -B DPVSCF OPJSF FU MFT QPJOUT QS©TFOUFOU MFT MJNJUFT PCTFSW©FT -B DPVSCF. OPJSF FO QPJOUJMM©T JOEJRVF MB MJNJUF B॒FOEVF FU MFT CBOEFT WFSUF FU KBVOF NPOUSFOU MFT E©WJBUJPOT FU TVS MB QS©EJDUJPO .

(27) YY " य़F EJTUSJCVUJPOT PG m`` j j PS m`` j JO UIF Z+KFUT DPOUSPM SFHJPO PG UIF H ! Z Z (⇤) ! `q. TFBSDI . " य़F EJTUSJCVUJPO PG UIF .7D bUBHHJOH FWFOU DBUFHPSJFT CBTFE PO UIF UXP TJHOBM KFUT JO UIF Z+KFUT DPOUSPM SFHJPO JO UIF VOUBHHFE HH' " BOE UBHHFE HH' # DIBO OFMT PG UIF H ! Z Z (⇤) ! `q TFBSDI . " य़F EJTUSJCVUJPO PG UIF .7D bUBHHJOH FWFOU DBUFHPSJFT CBTFE PO UIF UXP TJH. OBM KFUT JO UIF W ± +KFUT bUBH " BOE bUBH # DPOUSPM SFHJPOT PG UIF H ! Z Z (⇤) ! ⌫q TFBSDI. .

(28) YYJ. List of Tables . 1SPQFSUJFT PG UIF RVBSLT <> . . . 1SPQFSUJFT PG UIF MFQUPOT <> . . . 1SPQFSUJFT PG UIF HBVHF CPTPOT <> . . . 0WFSWJFX PG DPVQMJOHT JO UIF GPVS NPTU DPNNPO UZQFT PG )%. NPEFMT  u  d BOE  ` EFOPUF UIF DPVQMJOH UP VQUZQF RVBSLT EPXOUZQF RVBSLT BOE MFQUPOT SF TQFDUJWFMZ <>. . . 1FSGPSNBODF SFRVJSFNFOUT PG UIF "5-"4 EFUFDUPS TZTUFNT . . 1SFDJTJPO PG UIF *OOFS %FUFDUPS USBDLFST . . "O PWFSWJFX PG UIF "5-"4 DBMPSJNFUFS DPNQPOFOUT . . 0WFSWJFX PG UIF TQFDJ੗DBUJPOT PG UIF "5-"4 .VPO 4QFDUSPNFUFS . . 1FSDFOUBHF PG EBUB SFDPSEFE EVSJOH 3VO CZ UIF "5-"4 EFUFDUPS TZTUFNT UIBU JT. . DMBTTJ੗FE BT TVJUBCMF GPS QIZTJDT BOBMZTJT p 4VNNBSZ PG UIF 3VO USJHHFST VTFE JO UIF H ! Z Z ! ` BOBMZTJT VTJOH s = 5F7 EBUB . . य़F EJTDSJNJOBUJOH WBSJBCMFT VTFE JO UIF -) FMFDUSPO JEFOUJ੗DBUJPO BQQSPBDI GPS UIF -004& XPSLJOH QPJOU . . 4VNNBSZ PG UIF MFQUPO QSFTFMFDUJPO SFRVJSFNFOUT . . 4VNNBSZ PG UIF SFRVJSFNFOUT JNQPTFE JO UIF EJMFQUPO QBJSJOH BOE RVBESVQMFU. . TFMFDUJPO ¯ Z+MJHIU KFUT BOE t¯t CBDLHSPVOE DPNQPOFOUT 5SBOTGFS GBDUPST GPS UIF Z + bb. . 1SPCBCJMJUZ GPS UIF UISFF `èe CBDLHSPVOE DPNQPOFOUT UP QBTT UIF OPNJOBM FWFOU TFMFDUJPO JO UIF e BOE µe ੗OBMTUBUFT य़FTF UISFF DPNQPOFOUT PSJHJOBUF GSPN MJHIU੘BWPVSFE RVBSLT GBLJOH BO FMFDUSPO f QIPUPO DPOWFSTJPO BOE '43 DPOUSJ CVUJPO BOE UIF TFNJMFQUPOJD EFDBZT PG IFBWZ੘BWPVSFE RVBSLT q य़F RVPUFE FSSPST JODMVEF TZTUFNBUJD VODFSUBJOUJFT BOE UIF TUBUJTUJDBM VODFSUBJOUZ BSJTJOH GSPN UIF .$ FTUJNBUJPO .

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(32) YYW. Til Finn og Merete.

(33)

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(36) . CHAPTER The Standard Model and Beyond 2.1. 2. The Standard Model of Particle Physics. य़F 4UBOEBSE .PEFM 4. PG QBSUJDMF QIZTJDT EFTDSJCFT B QBOPSBNB PG FMFNFOUBSZ QBSUJDMFT UIFJS GVOEBNFOUBM QSPQFSUJFT BT XFMM BT UIFJS JOUFSBDUJPO WJB UISFF PG UIF GPVS LOPXO GVOEBNFOUBM GPSDFT UIF FMFDUSPNBHOFUJD UIF XFBL BOE UIF TUSPOH GPSDF UIF MB॒FS UXP VOJGZJOH JOUP UIF FMFDUSPXFBL &8 GPSDF BU TVਖ਼DJFOUMZ MBSHF FOFSHZ TDBMFT य़F 4. JT B MPDBMMZ HBVHF JOWBSJBOU UIFPSZ PG UIF GPSN 46$ ⇥46- ⇥6: *O UIJT OPUBUJPO $ SFGFST UP UIF DPMPVS DIBSHF PG UIF TUSPOH GPSDF : SFGFST UP UIF XFBL IZQFSDIBSHF XIJMF - SFGFST UP UIF GBDU UIBU POMZ MFॏIBOEFE GFSNJPOT JOUFSBDU JO UIF XFBL GPSDF य़F TUSPOH JOUFSBDUJPO BMTP LOPXO BT RVBOUVN DISPNP EZOBNJDT 2$% USBOT GPSNT BDDPSEJOH UP UIF HSPVQ 46$ XIJMF UIF FMFDUSPXFBL JOUFSBDUJPO PCFZT JOWBSJBODF VOEFS 46- ⇥6: USBOTGPSNBUJPOT < > "DDPSEJOH UP UIF 4. UIF WJTJCMF NB॒FS TVSSPVOEJOH VT JT DPOTUJUVUFE CZ GFSNJPOT JF QBSUJDMFT DBSSZJOH TQJO 5XP UZQFT PG GFSNJPOT BSF EJTUJOHVJTIFE RVBSLT BOE MFQUPOT UIF QSPQFSUJFT PG XIJDI BSF EJTDVTTFE JO 5BCMF BOE 5BCMF य़F 4. EFTDSJCFT TJY RVBSLT VQ u EPXO d. TUSBOHF s DIBSN c CFBVUZ b BOE UPQ t BOE TJY MFQUPOT UIF FMFDUSPO e UIF NVPO µ UIF UBV ⌧ BOE UISFF OFVUSJOPT ⌫e, ⌫ µ, ⌫⌧ BNPOH UIFJS DPSSFTQPOEJOH BOUJQBSUJDMFT "T JOEJDBUFE JO 5BCMF BOE 5BCMF CPUI RVBSLT BOE MFQUPOT BSF TFHNFOUFE JOUP UISFF HFOFSBUJPOT XIJDI BSF DIBSBDUFSJTFE CZ WBTUMZ EJ੖FSFOU NBTTFT TQBOOJOH PWFS PSEFST PG NBHOJUVEF य़F UISFF GPSDFT UIBU BSF EFTDSJCFE CZ UIF 4. BSF NFEJBUFE CZ UIF TQJO HBVHF CPTPOT य़F NBTTMFTT QIPUPO . NFEJBUFT UIF FMFDUSPNBHOFUJD GPSDF UIF W + W BOE Z CPTPOT DPMMFDUJWFMZ LOPXO BT UIF WFDUPS CPTPOT V NFEJBUF UIF XFBL JOUFSBDUJPOT XIJMF UIF NBTTMFTT HMVPOT g NFEJBUF UIF TUSPOH GPSDF य़F QSPQFSUJFT PG UIF HBVHF CPTPOT BSF TVNNBSJTFE JO 5BCMF . य़SPVHIPVU UIJT UIFTJT OBUVSBM VOJUT BSF VTFE JF ~ = c = 1 *O UIJT OPUBUJPO TQJO JT B EJNFOTJPOMFTT RVBOUJUZ BOE NBTT JT NFBTVSFE JO FMFDUSPO WPMUT F7 .

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(43) . 2.3. Constraints on the Higgs Boson Mass BSJTFT GSPN UIF USJWJBMJUZ CPVOE 4JODF UIF RVBSUJD )JHHT TFMGDPVQMJOH JT FYQFDUFE UP JO DSFBTF XJUI UIF FOFSHZ TDBMF PG B HJWFO QSPDFTT B DVUP੖ TDBMF ⇤ NVTU CF EF੗OFE XIFSF OFX QIZTJDT JT FYQFDUFE UP BQQFBS *G UIF WBMJEJUZ PG UIF 4. FYUFOET VQ UP (F7 NBTTFT BCPWF m h = (F7 BSF OPU QFSNJ॒FE )PXFWFS JG SFTUSJDUFE UP UIF FMFDUSPXFBL TDBMF m h DPVME SFBDI 5F7 -BTUMZ B UIFPSFUJDBM DPOTUSBJOU JT TFU CZ UIF WBDVVN TUBCJMJUZ CPVOE य़F )JHHT TFMGDPVQMJOH JT JNQBDUFE CZ DPOUSJCVUJPOT GSPN GFSNJPO BOE HBVHF CPTPOT MPPQT TPNF PG XIJDI IBWF OFHBUJWF TJHO *G UIF WBMVF PG m h JT UPP MPX UIF TJHO PG UIF RVBSUJD UFSN JO &RVBUJPO CFDPNFT OFHBUJWF UIF SFTVMU CFJOH UIBU UIF NJOJNVN PG UIF QPUFOUJBM EJTBQQFBST य़VT m h NVTU CF BCPWF B DFSUBJO UISFTIPME EFQFOEJOH PO UIF WBMVF PG DVUP੖ TDBMF ⇤ य़F BMMPXFE WBMVFT PG m h UBLJOH UIF MB॒FS UXP F੖FDUT JOUP BDDPVOU BSF QSFTFOUFE JO 'JHVSF " SFDFOU EJTDVTTJPO PG UIFTF UXP F੖FDUT JT HJWFO JO <> ‫* ۦ‬OEJSFDU FYQFSJNFOUBM DPOTUSBJOUT PO m h XFSF JNQPTFE GSPN FMFDUSPXFBL QSFDJTJPO NFBTVSFNFOUT BO BQQSPBDI NBEF QPTTJCMF CZ UIF GBDU UIBU UIF 4. )JHHT CPTPO DPOUSJCVUFT UP UIF SBEJBUJWF DPSSFDUJPOT BQQFBSJOH JO FMFDUSPXFBL UIFPSZ 'PS FYBNQMF CZ JODPSQPSBU JOH UIF FMFDUSPXFBL QSFDJTJPO EBUB PCUBJOFE XJUI UIF FYQFSJNFOUT BU UIF 4-$ -&1 BOE 5FWBUSPO EJTQMBZFE JO 'JHVSF B JO B DPNCJOFE ੗U UIF DPOTUSBJOU PO m h QSFTFOUFE JO 'JHVSF C XBT EFSJWFE य़JT MB॒FS FYIJCJU TIPXT UIF. 2. PG UIF ੗U UP UIF DPNCJOFE. NFBTVSFNFOUT BT B GVODUJPO PG m h XJUI UIF NPTU MJLFMZ WBMVF CFJOH m h = + (F7. 'VSUIFSNPSF B VQQFS $PO੗EFODF -FWFM $- PG m h < (F7 XBT JNQPTFE <>. ‫ ۦ‬%JSFDU FYQFSJNFOUBM DPOTUSBJOUT PO m h XFSF JNQPTFE CZ )JHHT CPTPO TFBSDIFT QFS GPSNFE BU -&1 BOE BU UIF 5FWBUSPO "T TFFO JO 'JHVSF UIF -&1 FYQFSJNFOUT FTUBC MJTIFE B MPXFS CPVOE PG m h > (F7 BU $- <> XIJMF UIF 5FWBUSPO FYQFSJ NFOUT FYDMVEFE UIF QSFTFODF PG B 4. )JHHT CPTPO JO UIF JOUFSWBM < m h < (F7 BOE < m h < (F7 BU $- <>. . य़F FYQFSJNFOUBM UFSNJOPMPHZ VTFE JO UIJT TFDUJPO JT SFWJFXFE JO $IBQUFS .

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(46) . Chapter 2. The Standard Model and Beyond. २. ३. १. ४. '९७ॻॸ५ 3FTVMUT QSFTFOUFE CZ UIF "5-"4 BOE $.4 DPMMBCPSBUJPOT JO +VMZ JO SFMBUJPO UP UIF 4. )JHHT CPTPO EJTDPWFSZ < > य़F FYQFSJNFOUBM UFSNJOPMPHZ BQQFBSJOH JO UIJT ੗HVSF JT SFWJFXFE JO $IBQUFS " B BOE # य़F PCTFSWFE VQQFS MJNJU PO UIF TJHOBM TUSFOHUI µ BT B GVODUJPO PG m h BOE UIF FYQFDUBUJPO VOEFS UIF CBDLHSPVOEPOMZ IZQPUIFTJT GPS "5-"4 BOE $.4 " C BOE $ य़F PCTFSWFE MPDBM p0 WBMVF BT B GVODUJPO PG m h BOE UIF FY QFDUBUJPO GPS B 4. )JHHT CPTPO TJHOBM IZQPUIFTJT BU UIF HJWFO m h WBMVF GPS "5-"4 BOE $.4 " D BOE % य़F CFTU੗U TJHOBM TUSFOHUI µˆ BT B GVODUJPO PG m h GPS "5-"4 BOE $.4.

(47) . 2.5. Production and Decay. XJUI B WFDUPS CPTPO 7) BOE BTTPDJBUFE QSPEVDUJPO XJUI B UPQRVBSL QBJS ॒) य़F MFBEJOHPSEFS EJBHSBNT PG UIFTF QSPDFTTFT BSF TIPXO JO 'JHVSF "T XJMM CF EFNPOTUSBUFE UISPVHIPVU UIJT UIFTJT UIF BCTFODF PS QSFTFODF PG CZQSPEVDUT DSFBUFE XJUI UIF )JHHT CPTPO TVDI BT KFUT GSPN UIF 7#' NFDIBOJTN PS B EFDBZJOH WFDUPS CPTPO GSPN UIF 7) NFDIBOJTN DBO CF FYQMPJUFE JO FYQFSJNFOUBM TUVEJFT UP EJTUJOHVJTI UIF EJ੖FSFOU QSPEVDUJPO NFDIBOJTNT 'JHVSF TIPXT UIF 4. )JHHT CPTPO QSPEVDUJPO DSPTTTFDUJPO PG UIF GPVS NFDIBOJTNT BT B p GVODUJPO PG UIF )JHHT CPTPO NBTT JO UIF SBOHF  m h  (F7 BU s = 5F7 "T TFFO UIF HH' BOE 7#' NFDIBOJTNT EPNJOBUF UIF QSPEVDUJPO XJUI HH' CFJOH NPSF UIBO BO PSEFS PG. NBHOJUVEF MBSHFS UIBO 7#' JO UIF MPXNBTT SFHJNF XIFSF UIF 4. )JHHT CPTPO XBT EJTDPWFSFE "MTP PCTFSWFE GSPN 'JHVSF JT UIF WFSZ NPEFTU DPOUSJCVUJPO GSPN BTTPDJBUFE QSPEVDUJPO XIJDI GBMMT TUFFQMZ XJUI m h BOE CFDPNFT OFHMJHJCMF BCPWF NBTTFT PG (F7 य़F DPOUSJCVUJPO GSPN UIF ॒) NFDIBOJTN JT BQQSPYJNBUFMZ B GBDUPS PG UXP TNBMMFS UIBO UIF 7) NFDIBOJTN BOE JT UIFSFGPSF OPU DPOTJEFSFE JO UIF BOBMZTFT PG UIJT UIFTJT 'JHVSF BMTP EJTQMBZT UIF JODMVTJWF )JHHT CPTPO p p p QSPEVDUJPO DSPTTTFDUJPO BU s = 5F7 s = 5F7 BOE s = 5F7 XIJDI DPSSFTQPOE UP UIF DPMMJTJPO FOFSHJFT JO UIF EJ੖FSFOU EBUBUBLJOH QFSJPET PG UIF -)$ "T TFFO JO UIJT FYIJCJU UIF UPUBM QSPEVDUJPO DSPTTTFDUJPO PG UIF 4. )JHHT CPTPO JODSFBTFT CZ VQ UP POF PSEFS PG NBHOJUVEF CFUXFFO p p s = 5F7 BOE s = 5F7 य़F DPVQMJOH TUSFOHUI PG UIF 4. )JHHT CPTPO JT QSPQPSUJPOBM UP UIF NBTT PG UIF QBSUJDMF JU JOUFSBDUT XJUI .PSF TQFDJ੗DBMMZ UIF DPVQMJOH TUSFOHUI JT QSPQPSUJPOBM UP UIF GFSNJPO NBTT BOE QSPQPSUJPOBM UP UIF TRVBSF PG UIF CPTPO NBTT य़FSFGPSF GPS B HJWFO WBMVF PG m h UIF EPNJOBOU g f g. qi. f. f. f W /Z. W /Z. h. W /Z. qj. १. qi0 h q0j. २. h. qi. g. h f. qi. g ३. ४. '९७ॻॸ५ -FBEJOHPSEFS EJBHSBNT GPS UIF GPVS EPNJOBOU )JHHT QSPEVD UJPO NFDIBOJTNT BU UIF -)$ " HMVPOGVTJPO HH' # WFDUPS CPTPOGVTJPO 7#' $ BTTPDJBUFE QSPEVDUJPO XJUI B WFDUPS CPTPO 7) % BTTPDJBUFE QSPEVDUJPO XJUI B UPQRVBSL QBJS ॒) .

(48) . Chapter 2. The Standard Model and Beyond. H (N. NLO. +NN. LL. 10 pp →. 1. pp. →. pp. →. qqH. (NNL. QC. D+. OQ. CD +. W H (N (N NL NL O O QC QC pp D → D + ttH +N (N LO NLO LO EW EW QC ) ) D). -1. 10. ZH. NLO. NLO. EW. ). EW). 102. pp. 10. pp pp. 1. LHC HIGGS XS WG 2012. s= 8 TeV. σ(pp → H+X) [pb]. pp →. LHC HIGGS XS WG 2012. σ(pp → H+X) [pb]. 102. →. → →. H+ X H+ X H+. X. 10-1. at. s= 1. 4T. eV. at at. s= 8. Te. V. s= 7T eV. 10-2 80 100. 200. 300. 400. 100 200 300 400. 1000 MH [GeV]. १. 500 600 700 800 900 1000 MH [GeV]. २. bb. 10-1. ττ. gg. WW. ZZ. 103. LHC HIGGS XS WG 2013. 1. ΓH [GeV]. LHC HIGGS XS WG 2013. Higgs BR + Total Uncert. '९७ॻॸ५ 4. )JHHT CPTPO QSPEVDUJPO DSPTTTFDUJPO CSPLFO EPXO CZ QSP p p EVDUJPO NFDIBOJTNpBU s = 5F7 p " BOE JODMVTJWFMZ GPS s = 5F7 s = 5F7 BOE s = 5F7 # <>. 102 10. cc. 1. 10-2 γ γ Zγ. 10-1. 10-3. 10-2 µµ. 10-4. 90. 200. 300 400. 1000. 10-3 80 100. 200. 1000 MH [GeV]. MH [GeV]. १. 300. २. '९७ॻॸ५ 4. )JHHT CPTPO CSBODIJOH SBUJPT " BOE UPUBM XJEUI BT B GVODUJPO PG m h # <>. EFDBZ PG UIF 4. )JHHT CPTPO XJMM CF UP UIF IFBWJFTU LJOFNBUJDBMMZ BDDFTTJCMF ੗OBMTUBUF IPXFWFS UIF EFDBZT UP UIF NBTTJWF HBVHF CPTPOT BSF GBWPVSFE य़JT CFIBWJPVS JT JMMVTUSBUFE JO 'JHVSF B XIJDI QSFTFOUT UIF CSBODIJOH SBUJP PG UIF 4. )JHHT CPTPO BT B GVODUJPO PG m h "T PCTFSWFE UIF h ! bb¯ EFDBZ EPNJOBUFT BU MPX NBTT XIJMF UIF EJCPTPO DIBOOFMT h ! Z Z BOE h ! WW. EPNJOBUF GSPN m h ⇠ (F7 BOE VQ XIJDI JT UIF UISFTIPME XIFSF UIFTF EFDBZT CFDPNF QFSNJ॒FE CZ LJOFNBUJDT य़F h ! Z Z EFDBZ XIJDI JT UIF EFDBZ PG JOUFSFTU UP UIJT UIFTJT JT UIF TFDPOENPTU.