Speaker: Wei Wang, Sun Yat-Sen University, Guangzhou
Abstract: Neutrino mass is currently the only sign of new physics beyond the Standard Model (SM) of particle physics. Unfortunately, due to the challenges in measuring the three absolute neutrino masses, we currently only know the two mass-squared differences manifested in neutrino oscillation data. The mass ordering is very likely to be the first experimental handle we could have on physics related to neutrino mass. Thus a concrete experimental measurement could provide invaluable clues to the fundamental questions in particle physics. The means to measure the neutrino mass ordering via neutrino oscillation can be grouped into two types: one natural approach is to take the advantage of the so-called Matter Effect which happens in solar neutrinos and has made differentiating two of the three neutrino mass eigenstates possible; the other is quite unique in that it carefully arranges two oscillation frequencies into the same energy spectrum which would exhibit different phase shifts under different mass orderings. In this talk, we will give a general review on neutrino physics, the discovery of neutrino oscillation and its recent experimental progresses, and explain the different experimental efforts of measuring neutrino mass ordering. The second type approach utilizing nuclear reactor neutrinos was made possible by the unexpected large value of the third mixing angle θ13 measured by the current generation short-baseline reactor neutrino experiments. We will focus more on the only neutrino oscillation experiment taking the second type approach: the Jiangmen Underground Neutrino Observatory (JUNO), which plans to measure neutrino mass ordering utilizing powerful nuclear reactors in Southern China. We will explain its design, recent progresses and its physics opportunities.