Effects of heavy Majorana neutrinos on lepton flavor violating processes
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AuthorHernández Tomé, G.; Illana Calero, José Ignacio; Masip Mellado, Manuel; López Castro, G.; Roig, P.
American Physical Society
Hernández-Tomé, G., Illana, J. I., Masip, M., Castro, G. L., & Roig, P. (2020). Effects of heavy Majorana neutrinos on lepton flavor violating processes. Physical Review D, 101(7), 075020.
SponsorshipThis work was supported in part by the Spanish Ministry of Science, Innovation and Universities, under Grant No. FPA2016-78220-C3-1,2,3- P (fondos FEDER), and Junta de Andalucía, Grants No. FQM 101 and No. SOMM17/6104/UGR. G. H. T. wants to acknowledge financial support from Conacyt through the program “Estancia Postdoctoral en el Extranjero.” The work of P. R. has been partially funded by Conacyt through the Project No. 250628 (Ciencia Básica) and Fondo SEP-Cinvestav 2018 (Project No. 142).
The observation of lepton flavor violating processes at colliders could be a clear signal of a non-minimal neutrino sector. We define a 5-parameter model with a pair of TeV fermion singlets and arbitrary mixings with the three active neutrino flavors. Then we analyze several flavor violating transitions (ℓ→ℓ′γ,ℓ′ℓ′′ℓ¯′′′ or μ−e conversions in nuclei) and Z→ℓ¯ℓ′ decays induced by the presence of heavy neutrinos. In particular, we calculate all the one-loop contributions to these processes and present their analytic expressions. We focus on the genuine effects of the heavy Majorana masses, comparing the results in that case with the ones obtained when the two heavy neutrinos define a Dirac field. Finally, we use our results to update the bounds on the heavy-light mixings in the neutrino sector.