Sensitivity of the T2K accelerator-based neutrino experiment with an Extended run to $20\times10^{21}$ POT

TL;DR

This paper evaluates the potential of an extended T2K neutrino experiment to observe CP violation with higher significance by increasing proton exposure, considering upgrades and analysis improvements before next-generation experiments.

Contribution

It analyzes the physics reach of extending T2K's run to $20\times 10^{21}$ POT, highlighting its potential to observe CP violation before 2026.

Findings

Extended run increases sensitivity to CP violation.

Potential to observe CP violation at 3σ significance.

Upgrades improve experimental capabilities.

Abstract

Recent measurements at the T2K experiment indicate that CP violation in neutrino mixing may be observed in the future by long-baseline neutrino oscillation experiments. We explore the physics program of an extension to the currently approved T2K running of $7.8\times 10^{21}$ protons-on-target to $20\times 10^{21}$ protons-on-target,aiming at initial observation of CP violation with 3$\,\sigma$ or higher significance for the case of maximum CP violation. With accelerator and beam line upgrades, as well as analysis improvements, this program would occur before the next generation of long-baseline neutrino oscillation experiments that are expected to start operation in 2026.