Seminarium Fizyki Wielkich Energii

T2K (Tokai to Kamioka) is a long-baseline neutrino oscillation experiment located in Japan. One of the most challenging tasks of T2K is to study whether CP is violated in the lepton sector, which is suggested by recent T2K results. By utilizing the near detector (ND280) data, T2K can constrain neutrino interaction and flux uncertainties by fitting a parameterized model to data. This allows for a significant reduction of the systematic uncertainties in neutrino oscillation analyses.One of two fitters responsible for ND fit uses Markov Chain Monte Carlo (MCMC) Method. Great benefit of MCMC is that it returns distribution for each parameter rather than one just one best fit value.ND280 fit analysis, planned to be released this year, introduced lots of improvement, including the new photon-proton selection and new systematic parameter giving lots of freedom in nuclear effect description like Short Range Correlations and Pauli Blocking.