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| Home > Publications database > Jet Energy Measurements at ILC:Calorimeter DAQ Requirements and Application in Higgs Boson Mass Measurements |
| Book/Report/Dissertation / PhD Thesis | PUBDB-2017-11891 |
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2017
Verlag Deutsches Elektronen-Synchrotron
Hamburg
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Please use a persistent id in citations: doi:10.3204/PUBDB-2017-11891
Report No.: DESY-THESIS-2017-045
Abstract: The idea of spontaneous symmetry breaking as the mechanism through which elementaryparticles gain mass has been confirmed by the discovery of the Higgs boson at the CERNLarge Hadron Collider. Studying the Higgs boson properties are of great importance toverify the Standard Model predictions. Any deviation from these predictions could uncoverphysics beyond the Standard Model. The mass of the Higgs boson is one of the importantparameters of the Standard Model. The precise determination of the Higgs boson mass is ofinterest in its own right and also for other Higgs physics studies since it enters as parametricuncertainty into the extraction of the partial width from branching ratio measurements.The International Linear Collider (ILC) is a future polarised e+e- collider designedfor precision physics studies. The Higgs boson decay to a pair of bottom quarks H ! bbhas the largest branching ratio of all Higgs decays, providing a large dataset for physicsanalyses. The possibility of measuring the Higgs boson mass in the e+e- ! ZH ! qqbbchannel is investigated in this thesis for centre-of-mass energies of 350 GeV and 500 GeV.Since the Higgs boson mass is reconstructed from two b jets, the jet energy resolution hasa high impact on the measurement. A new method to estimate the jet energy resolution foreach jet individually is developed in this thesis. The jet-specific energy resolution is thenused in the analysis for the Higgs boson mass measurements. Various strategies for theHiggs boson mass measurement are investigated. For an integrated luminosity of 1000 fb1and a beam polarisation of (0:8,+0:3), statistical uncertainties of 42 MeV and 89 MeV areachieved for the centre-of-mass energies of 350 GeV and 500 GeV, respectively. Varioussources of systematic uncertainties are also discussed.These results are obtained using a full GEANT4-based simulation of the InternationalLarge Detector (ILD) concept. The jet energy resolution required for the Higgs boson massmeasurement can only be achieved using the particle flow approach to reconstruction. Theparticle flow approach requires highly-granular calorimeters and a highly efficient trackingsystem. The CALICE collaboration is developing highly-granular calorimeters for suchapplications. One of the challenges in the development of such calorimeters with millionsor read-out channels is their Data Acquisition System (DAQ) system. The second part ofthis thesis involves contributions to development of a new DAQ system for the CALICEscintillator calorimeters. The new DAQ system fulfils the requirements for the prototypestests while being scalable to larger systems. The requirements and general architecture ofthe DAQ system is outlined in this thesis. The new DAQ system has been commissionedand tested with particle beams at the CERN Proton Synchrotron test beam facility in 2014,results of which are presented here.v
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