Applications of linearised oscillation models on the T2K experiment

T2K is a long-baseline neutrino oscillation experiment measuring νμ disappearance and νe appearance with a baseline of 295 km and a narrow-band beam peaking in energy at around 0.6 GeV. This thesis presents a linearised oscillation probability model for the phase angle δCP, designed to complement standard analyses used in this experiment. We demonstrate that the framework provides a universal method for performing T2K sensitivity studies, and characterisation of systematics, that avoids almost all of the problems with commonly used metrics, most notably the dependence on the choice of trial point. Furthermore, we show how it restores the validity of well-known asymptotic approximations, allowing the likelihood to be described by a simple Gaussian form which could reduce or eliminate the need for computationally expensive tools such as MCMC or Frequentist toys sampling when quoting results at high significance.