Higher dimensional LNV operators and their renormalization




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榎本一輝氏 ( 大阪大学 )





Ryutaro Matsudo / matsudo-AT-post.kek.jp


Although the Standard Model (SM) is a successful theory, some mysterious phenomena such as tiny neutrino masses are observed. We need physics beyond the SM to explain these phenomena. Observed tiny neutrino masses would indicate the lepton number violation (LNV) in new physics. If the scale of LNV is much higher than the electroweak scale, low-energy physics is described by the effective field theory with higher dimensional LNV operators. Therefore, the higher dimensional LNV operator is one of the important clues to search for new physics. In this seminar, I will talk about our two studies about LNV operators. One is about the operator between a same-sign lepton pair and a pair of W bosons, which is generated from d=7 and 9 LNV operators. We studied how to test this operator by using data of neutrino oscillation, neutrinoless double beta decay, muon-positron conversion, and future high-energy colliders. The other is about the renormalization of higher dimensional LNV operators. Some higher dimensional LNV operators generate Majorana neutrino masses via divergent loop diagrams, and the renormalization is needed for model-independent analyses. We investigated d=5 and 7 LNV operators and Majorana neutrino masses at one-loop level, and we found that divergence at one-loop level can be renormalized by using counter term from higher dimensional operators. The former topic is based on Phys. Rev. D101, 115019 (arXiv:2002.12265), and the latter is based on the work in progress.