Investigation of the Effects of Invisible Neutrino Decay at the Proposed ESSnuSB Experiment

Abstract: This thesis studies neutrino oscillations at the proposed ESSnuSB experiment and the effects of invisible decay, where the neutrino mass states are assumed to be able to decay, on the planned measurements and the physics potential for this experiment to detect neutrino decays. This is accomplished by simulating a combined scenario of neutrino oscillations and invisible neutrino decay. It is found that the ESSnuSB experiment would be able to put a bound on the decay parameter $\tau_3 / m_3 = 2.64 (1.68) \times 10^{-11}$~s/eV for the baseline option $360 (540)$~km at $3\sigma$. Further, the effect of invisible neutrino decay on measurements of CP-violation and the precision measurements of $\delta_{\mathrm{CP}}$ for both baseline options are investigated. The results show that the effect is not significant in any case for CP-violation measurements. A significant difference in the precision measurements of $\delta_{\mathrm{CP}}$ is found only when decay is assumed to exist but is not accounted for in the theoretical model.