The search for CP violation in neutrino oscillations at T2K

Thesis

T2K is a long-baseline neutrino oscillation experiment, designed to study the oscillation of a high-intensity muon neutrino beam produced by the J-PARC ac- celerator facility. Neutrinos are detected 295 km downstream of the production point at Super-Kamiokande, a 50 kt water Cherenkov detector capable of differ- entiating between muon neutrino and electron neutrino events. Two beam configurations are possible at T2K, each used to create neutrino beams composed of predominantly neutrinos or anti-neutrinos. Comparisons of the disappearance of muon neutrinos and the appearance of electron neutrinos in the neutrino and anti-neutrino beams are used to measure the neutrino oscillation parameters.

Presented in this thesis are the results of many analyses designed to study various combinations of the Super-Kamiokande oscillation data sets. Analyses considering the antineutrino beam data sets found no substantial evidence for ν ̄e appearance in a ν ̄μ beam or ν ̄μ oscillation inconsistent with observed νμ oscillation. A combined study of all available Super-K oscillation samples measured the CP violating phase δCP and the sine square of the mixing angle θ(13).

This analysis excluded δCP = 0 at the 2σ confidence level under both normal and inverted ordering hypotheses and produced a constraint of -2.978 rad < δCP < -0.467 rad in the normal ordering hypothesis.

Authors: Shah, RK

• DOI: 10.5287/ora-2r74qzzyw
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: CP symmetry; charge parity violation; neutrino oscillation; mixing angle
• Subjects: Physics; Experimental particle physics; Neutrino oscillations