Type I + II Seesaw Model in light of the New Neutrino Oscillation Measurements

Global analysis of neutrino oscillation data slightly favors normal mass ordering. In this work, we investigate an extended scalar sector that naturally gives rise to a type I + II seesaw mechanism after spontaneous symmetry breaking and explore the interplay between collider physics and lepton flavor violation, adopting normal ordering. In particular, we focus on the rare muon decays μ e γ and μ 3e and the same-sign dilepton searches at LHC, a canonical signature of a doubly charged scalar. We conclude that neither the precise value of the sum of the neutrino masses, taken from DESI data that favors m_ν=0. 07~eV, nor alternative cosmological fits which prefer a more relaxed limit m_ν=0. 1~eV, significantly changes the theoretical prediction for these rare decays. However, we observe an interesting interplay between collider physics and lepton flavor violation depending on the choices of the vacuum expectation value of the triplet scalar. In particular, we find that μ 3e is more constraining than μ eγ, and the μ 3e decay can yield a lower mass limit of 3~TeV on the doubly charged scalar, surpassing current LHC constraint.