APEC Seminar (Astronomy - Particle Physics - Experimental Physics - Cosmology)

Speaker: Shao-Feng Ge (Kavli IPMU)
Title: The Leptonic Dirac CP Phase from Residual Symmetry and Muon Decay at Rest Experiment
Date: Wed, Nov 01, 2017, 13:30 - 14:30
Place: Seminar Room A
Abstract: With the 1-3 mixing angle measured at reator neutrino experiments, Daya Bay and RENO, there are still three unknown oscillation variables, the neutrino mass hierarchy, the octant of the atmospheric mixing angle, and the leptonic CP phase. Of them, the CP phase is the most difficult to measure precisely and important for distinguishing flavor symmetries. I will first talk about residual symmetries, which takes the role as low energy effective field theory for neutrino mixing and is an analogy of custodial symmetry in the electroweak sector, to predict the CP phase from the measured mixing angles. Then I introduce a new type of neutrino experiment with muon decay at rest to measure the CP phase. Currently, T2K, NOvA, and DUNE are designed for CP measurement. Nevertheless, they suffer from problems of degeneracy, efficiency, uncertainty, non-unitary mixing and non-standard interactions. All of them can be improved by simply adding a muon decay at rest (muDAR) source to T2(H)K, for example. The same configuration can also apply to next-generation medium baseline reactor neutrino experiments like JUNO and RENO-50, enhancing their physics potential. With only one source and no extra detectors, this dessign is much better than DAEdLAS which requires 3 sources, but only 20% duty factor and 4 times higher luminosity for each.

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