Tests Of A High Rate Pixel Detector For Cms Upgrade

Tests of a High Rate Pixel Detector for CMS Upgrade

CMS Pixel Detector Upgrade and Top Quark Pole Mass Determination

This thesis addresses two different topics, both vital for implementing modern high-energy physics experiments: detector development and data analysis. Providing a concise introduction to both the standard model of particle physics and the basic principles of semiconductor tracking detectors, it presents the first measurement of the top quark pole mass from the differential cross-section of tt+J events in the dileptonic tt decay channel. The first part focuses on the development and characterization of silicon pixel detectors. To account for the expected increase in luminosity of the Large Hadron Collider (LHC), the pixel detector of the compact muon solenoid (CMS) experiment is replaced by an upgraded detector with new front-end electronics. It presents comprehensive test beam studies conducted to verify the design and quantify the performance of the new front-end in terms of tracking efficiency and spatial resolution. Furthermore, it proposes a new cluster interpolation method, which utilizes the third central moment of the cluster charge distribution to improve the position resolution. The second part of the thesis introduces an alternative measurement of the top quark mass from the normalized differential production cross-sections of dileptonic top quark pair events with an additional jet. The energy measurement is 8TeV. Using theoretical predictions at next-to-leading order in perturbative Quantum Chromodynamics (QCD), the top quark pole mass is determined using a template fit method.

Development of a New Tracker for the CMS Upgrade Phase 2 and Study of the HL-LHC Physics Reach

The standard model of particle physics provides a coherent description of highenergy physics processes and has been hugely successful in providing experimental predictions. Among its long list of achievements, the most significant is arguably that of the discovery of the Higgs boson half a century after being theorised, providing the last cornerstone needed for the standard model to become fully consistent. Despite huge successes, the standard model still suffers from major shortcomings. On the path leading towards a better understanding of particle physics, an in-depth study of the Higgs boson is key. This relentless work of characterising the properties of the Higgs boson is currently being undertaken at the Large Hadron Collider, where high-energy proton collisions are being recorded by dedicated detectors, providing a continuous improvement to the understanding of the standard model. Amid tremendous achievements, some processes, remain too weak to be detected with the current installations. One such measurement is the combined production of two Higgs bosons allowing for a direct handle on the Higgs self-coupling parameter of the standard model. To maximise the physics reach of the collider, it will be subjected to a major upgrade, allowing for a strong increase in luminosity. Such a dramatic change will bring major challenges to the experiments recording these collisions and upgrades are required if they are to maintain their outstanding performance. This thesis explores the upgrade of the CMS silicon strip detector, centred around the in-beam characterisation of detector module prototypes and discusses the physics reach of the upgraded machine, with an emphasis on Higgs boson pair production in the bbWW(l) final state.