This thesis reports the calculation of neutrino production for the T2K experiment; the most precise a priori estimate of neutrino production that has been achieved for any accelerator-based neutrino oscillation experiment to date. The production of intense neutrino beams at accelerator facilities requires exceptional understanding of chains of particle interactions initiated within extended targets. In this thesis, the calculation of neutrino production for T2K has been improved by using measurements of particle production from a T2K replica target, taken by the NA61/SHINE experiment. This enabled the reduction of the neutrino production uncertainty to the level of 5%, which will have a significant impact on neutrino oscillation and interaction measurements by T2K in the coming years. In addition to presenting the revised flux calculation methodology in an accessible format, this thesis also reports a joint T2K measurement of muon neutrino and antineutrino disappearance, and the accompanying electron neutrino and antineutrino appearance, with the updated beam constraint.

This thesis reports the measurement of muon neutrino and antineutrino disappearance and electron neutrino and antineutrino appearance in a muon neutrino and antineutrino beam using the T2K experiment. It describes a result in neutrino physics that is a pioneering indication of charge-parity (CP) violation in neutrino oscillation; the first to be obtained from a single experiment. Neutrinos are some of the most abundant—but elusive—particles in the universe, and may provide a promising place to look for a potential solution to the puzzle of matter/antimatter imbalance in the observable universe. It has been firmly established that neutrinos can change flavour (or ‘oscillate’), as recognised by the 2015 Nobel Prize. The theory of neutrino oscillation allows for neutrinos and antineutrinos to oscillate differently (CP violation), and may provide insights into why our universe is matter-dominated. Bayesian statistical methods, including the Markov Chain Monte Carlo fitting technique, are used to simultaneously optimise several hundred systematic parameters describing detector, beam, and neutrino interaction uncertainties as well as the six oscillation parameters.

This book is based on the author's work in the T2K long-baseline neutrino oscillation experiment, in which neutrinos are generated by a proton beam and are detected by near and far neutrino detectors. In order to achieve the precise measurement of the neutrino oscillation, an accurate understanding of the neutrino beam and the neutrino interaction is essential. Thus, the author measured the neutrino beam properties and the neutrino interaction cross sections using a near neutrino detector called INGRID and promoted a better understanding of them. Then, the author performed a neutrino oscillation analysis using the neutrino beam and neutrino interaction models verified by the INGRID measurements. As a result, some values of the neutrino CP phase are disfavored at the 90% confidence level. If the measurement precision is further improved, we may be able to discover the finite CP phase which involves the CP violation. Thus, this result is an important step towards the discovery of CP violation in the lepton sector, which may be the key to understanding the origin of the matter–antimatter asymmetry in the universe.

In this thesis the author contributes to the analysis of neutrino beam data collected between 2010 and 2013 to identify νμ→νe events at the Super-Kamiokande detector. In particular, the author improves the pion–nucleus interaction uncertainty, which is one of the dominant systematic error sources in T2K neutrino oscillation measurement. In the thesis, the measurement of νμ→νe oscillation in the T2K (Tokai to Kamioka) experiment is presented and a new constraint on δCP is obtained. This measurement and the analysis establish, at greater than 5σ significance, the observation of νμ→νe oscillation for the first time in the world. Combining the T2K νμ→νe oscillation measurement with the latest findings on oscillation parameters including the world average value of θ13 from reactor experiments, the constraint on the value of δCP at the 90% confidence level is obtained. This constraint on δCP is an important step towards the discovery of CP violation in the lepton sector.

Reviews the current state of knowledge of neutrino masses and the related question of neutrino oscillations. After an overview of the theory of neutrino masses and mixings, detailed accounts are given of the laboratory limits on neutrino masses, astrophysical and cosmological constraints on those masses, experimental results on neutrino oscillations, the theoretical interpretation of those results, and theoretical models of neutrino masses and mixings. The book concludes with an examination of the potential of long-baseline experiments. This is an essential reference text for workers in elementary-particle physics, nuclear physics, and astrophysics.

The volume of these proceedings is devoted to a wide variety of items, both in theory and experiment, of particle physics such as electroweak theory, fundamental symmetries, tests of standard model and beyond, neutrino and astroparticle physics, hadron physics, gravitation and cosmology, physics at the present and future accelerators.

This book contains the proceedings of the Fifth International Conference on Physics Beyond the Standard Models of Particle Physics, Cosmology and Astrophysics. It presents a brilliant overview of the status and future potential and trends in experimental and theoretical particle physics, cosmology and astrophysics, in the complimentary sectors of accelerator, non-accelerator and space physics.