Seminarium Fizyki Wielkich Energii

The T2K long-baseline neutrino oscillation experiment in Japan continues to refine its sensitivity to the neutrino mixing parameters in its final years of operation. This seminar presents new developments in the analysis of T2K's far detector — the Super-Kamiokande water Cherenkov detector, located 295 km from the neutrino source — that will be incorporated in the upcoming oscillation result.The central contribution is a new multi-ring electron neutrino appearance sample, developed as part of my PhD work, targeting charged-current single-pion production — the second most dominant neutrino interaction at T2K's energies after quasi-elastic scattering. Its development, validation, and expected impact on the oscillation analysis are presented in detail. Recent advances in the evaluation of far detector systematic uncertainties and a brief overview of updates to the near detector analysis are also discussed.