The standard neutrino oscillation parametrization is defined by six independent parameters: three mixing angles (θ23, θ12 and θ13), two squared mass differences and a CP violation phase (δCP). By 2010, only θ13 and δCP were still unknown. Despite the non-zero measured values of θ12 and θ23, a non zero value of θ13 is also necessary to open the window to explore CP violation in the lepton sector. In 2011, T2K (accelerator based) and Double Chooz (reactor based) experiments showed an evidence of non-zero θ13. Nowadays, it is measured with a 1.8% uncertainty, lead by the Daya Bay reactor experiment. θ13 is today the most precisely known mixing angle. However, with the next generation of experiments, such as JUNO, DUNE and HK, it will become the least precise one. In this seminar, I shall review the past and present θ13 measurement status that I have witnessed for the past decade, putting it into perspective with respect to the general neutrino oscillation scenario. I addition I shall highlight the different ways, challenges and limitations to perform such a measurement, and what we can expect from the future projects under consideration.
Ioana Maris