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We conduct the first study of the T-odd correlations in tt events produced in p{bar p} collision at the Fermilab Tevatron collider that can be used to search for CP violation. We select events which have lepton+jets final states to identify t{bar t} events and measure counting asymmetries of several physics observables. Based on the result, we search the top quark anomalous couplings at the production vertex at the Tevatron. In addition, Geant4 development, photon identification, the discrimination of a single photon and a photon doublet from {pi}{sup 0} decay are discussed in this thesis.

Current understanding of particle physics postulates that there are 17 fundamental particles that interact via four fundamental forces - gravity, the strong force, the weak force, and the electromagnetic force. These fundamental particles can be classified by their spins into bosons, which are the force-carrying particles with integer spins, and fermions, which have half-integer spins. Fermions can be further divided into quarks and leptons. The particles and three of the four forces - all but gravity - are described by the Standard Model, a local SU(3) x SU(2) x U(1) gauge theory. Electromagnetic and weak interactions as described by Electroweak Theory or Quantum Electrodynamics, SU(2) x U(1). Strong interactions are described by Quantum Chromodynamics or QCD, SU(3). Fermions are grouped into three generations as shown in Table 1.1. Each generation consists of a leptonic doublet containing a charged and a neutral lepton and a weak isospin doublet containing two quarks. The first generation, containing the electron, the electron neutrino, the up quark, and the down quark, is the lightest generation and is thus the most frequently found in nature. The second generation contains the muon, the muon neutrino, the strange quark, and the charm quark. The third generation contains the …

The top quark is the heaviest known fundamental particle, with a mass of 172.0{sub -1.3}{sup +0.9}GeV. This is nearly twice the mass of the second heaviest known particle, the Z boson, and roughly the mass of a gold atom. Because of its unusually large mass, studying the top quark may provide insight into the Higgs mechanism and other beyond the standard model physics. Only two accelerators in the world are powerful enough to produce top quarks. The Tevatron, which first accelerated protons in 1983, has produced almost 400,000 top quarks, roughly half at each of its two detectors: DO and CDF. The LHC is a much newer accelerator which currently has accumulated about 0.5% as much data as the Tevatron. However, when running at full luminosity, the LHC is capable of producing a top quark about once every second and will quickly surpass the Tevatron as the leading producer of top quarks. This analysis uses data from the D0 detector at the Tevatron, which are described in chapter 3. Top quarks are produced most often in pairs of top and anti-top quarks through an interaction of the strong force. This production mode was first observed in 1995 at the Tevatron. …

Presented is a series of analyses which are central to the search for a low-mass Higgs boson. A search for ZZ production in the ZZ {yields} {ell}{sup -}{ell}{sup +}{nu}{bar {nu}} channel is introduced then the successful combination of this analysis with with the ZZ {yields} {ell}{sup +}{ell}{sup -}{ell}'{sup +}{ell}'{sup -} search to produce the first observation of the ZZ process at a hadron collider is then detailed. The final analysis presented is the search for the Higgs in the ZH {yields} {nu}{bar {nu}}b{bar b} channel and the interpretation as a ZZ {yields} {nu}{bar {nu}}b{bar b} search in order to validate the techniques. Common themes are discussed, such as multivariate techniques and instrumental backgrounds from energy measurement fluctuations and the tools used to combat them. The formalism of the statistical analysis of the final selected sample is introduced generally and demonstrated in the context of the above mentioned searches. The optimization of the selection through the identification of poorly reconstructed leptons is included as well as the utilization of b-quark identifying tools. Some space is given to jet reconstruction/identification and the Level 1 Calorimeter Trigger. The efficient identification and calibration of jets is central to many physics analysis especially in the …

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