Measurements of Neutrino Oscillation Angle theta_13

TL;DR

This paper reports the measurement of the neutrino oscillation angle theta_13, a key parameter in neutrino physics, based on recent experimental results including the author's involvement in the Double Chooz reactor experiment.

Contribution

It provides the first measurement of theta_13 and discusses its implications for future neutrino research, especially CP violation studies.

Findings

Theta_13 is non-zero and just below previous upper limits.

Measurement confirms neutrino oscillation parameters.

Results enable future CP violation experiments.

Abstract

Neutrinos exhibit an interesting phenomenon called 'neutrino oscillation', in which a neutrino changes its flavor after traveling some flight length. Many experiments measured the mixing angles and mass differences, but the angle $\theta_{13}$ had been unmeasured due to its smallness compared to others. During 2011 and 2012, series of new-generation neutrino experiments reported positive results in $\theta_{13}$ search, and its value has been determined to be just below the previous upper limit. The non-zero result of $\theta_{13}$ is a very good news for future of neutrino physics, since it opens a possibility of measuring the CP violation phase in the lepton sector. An introduction to neutrino oscillation and latest experimental results are presented. A detail is put on Double Chooz reactor experiment, in which the author is involved.