Observation of ν_μ→ν_e Oscillation in the T2K Experiment

In this thesis theauthor contributes to the analysis of neutrino beam data collected between 2010and 2013 to identify ?µ??e  events at the Super-Kamiokande detector. In particular,the author improves the pion–nucleus interaction uncertainty, which is one ofthe dominant systematic error sources inT2K neutrino oscillation measurement. In the thesis, the measurement of ?µ??e  oscillation in the T2K (Tokai toKamioka) experiment is presented and a new constraint on dCP is obtained. Thismeasurement and the analysis establish, at greater than 5s significance, theobservation of ?µ??e  oscillation for the first time in the world. Combiningthe T2K ?µ??e  oscillation measurement with the latest findings on oscillationparameters including the world average value of ?13 from reactor experiments,the constraint on the value of dCP at the 90% confidence level is obtained. This constraint on dCP is an important step towards the discovery of CPviolation in the lepton sector.