LHC Physics with Electrons and Photons and the Achievement of the Full Performance Potential of the CMS Electromagnetic Calorimeter

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The Large Hadron Collider (LHC), located at CERN near Geneva, Switzerland, will be the world's largest particle accelerator. The machine, which is due to begin operation in summer 2007 will collide high energy protons travelling in opposite directions around a 27 km ring. The Compact Muon Solenoid (CMS) is a general purpose detector and is one of four large particle detectors to be positioned at collision points around the ring. One of the key components of the CMS detector is the Electromagnetic Calorimeter (ECAL). This is composed of over 75000 lead tungstate crystals and is designed to accurately measure the positions and energies of electrons and photons. The proposed project is to ensure that the design performance potential of the CMS ECAL is fully exploited, and to play a decisive and leading role in the discovery of new physics at the LHC, focusing on the use of the electromagnetic calorimeter. One of the primary objectives of the LHC experimental program is to elucidate the origin of mass, in particular through the discovery the Higgs boson, an elementary particle predicted by the Standard Model of particle physics. The particle is unstable and when produced in proton-proton collisions at the LHC will immediately decay into less massive particles. It is the stable particles in the final state, such as electrons, muons or photons, which will be observed by the detector. The mass of the parent Higgs boson can be reconstructed from the combined momenta of the final state particles. The decay channels of the Higgs boson which yield the highest sensitivity for discovery at the LHC all have final states which may contain electrons or photons. The achievement of the full design performance of the CMS ECAL is therefore of crucial importance to the discovery of the Higgs boson. My primary task over the last two years has been to develop the first complete physics analysis with full simulation of the CMS detector for one of the most important channels for the discovery of the Higgs boson. One of the pre-requisites for any LHC physics analysis is accurate reconstruction of final state particles. The challenge for the CMS ECAL concerns the precise reconstruction of the positions and energies of electrons and photons and their accurate and efficient identification and selection. I am now the leading expert in these areas, and my objective for the first one to two years of the project will be to continue to focus on the development of robust reconstruction software in preparation for the start of the experiment. In the second or third year of the project I aim to take up a leading role, concerning the ECAL, in the commissioning of the CMS detector. The major task of performing the relative calibration of the 75000 ECAL crystals would be my next area of focus during early data taking. My next objective will be to study key Standard Model signals, and in particular, electrons produced from the decay of the W boson. As well as being the main channel used to calibrate the ECAL, this channel provides a detailed probe of the detector performance, and will be a key to understanding many new physics signals. The accurate and efficient reconstruction of electrons and photons in a precisely calibrated ECAL will provide the maximum possible potential for the discovery of new physics which may become accessible through the LHC. As the data taken by CMS accumulates, my experience from my current Higgs analysis and from previous analyses will place me in a strong position to act as a key player in the discovery and study of new physics signals using CMS data. I aim to take the lead in a number of physics analyses, extending my expertise to other Higgs boson decay channels. Finally, I will be able to use my knowledge and experience from the OPAL experiment to develop techniques to combine results from the different search channels to ensure the timely discovery of the Higgs boson and other new physics.