Speaker
Description
The Tokai-to-Kamioka (T2K) experiment is a long-baseline neutrino oscillation experiment, providing world-leading measurements of oscillation parameters and CP violation using the Super-Kamiokande (SK) water cherenkov detector, 295km downstream of a neutrino beam created at the Japan Proton Accelerator Research Complex (J-PARC). These measurements benefit from neutrino cross-section and beam flux constraint provided by ND280, a near detector positioned 280m from the J-PARC beam target.
In this talk, we present the latest developments to the T2K near detector fit, based on results and studies from previous iterations of this analysis. Using newly available time-of-flight information, ND280 particle track reconstruction has been updated to include backwards-going tracks, bringing ND280 efficiencies closer to that of SK. In addition, the neutrino cross section model has been updated, allowing for additional freedom in the low energy transfer region dominated by nuclear effects.
The performance of this updated T2K near detector analysis is compared to previous iterations, showcasing a similarly effective post-fit constraint using a more robust cross section model, with potential to propagate these improvements to the T2K oscillation analysis using SK. ND280 efficiency is expected to further improve with inclusion of data and systematics from the detector upgrade.