Complex Spinors and Unified Theories

Inverse Seesaw, dark matter and the Hubble tension

“…right-handed neutrinos. Furthermore, if a large Majorana mass is also included for the right-handed neutrinos, the smallness of neutrino masses is naturally explained through the hierarchy between this mass and the electroweak scale via the celebrated canonical type-I Seesaw [34][35][36][37]. Conversely, a Majorana mass significantly above the electroweak scale destabilizes the Higgs mass, worsening the electroweak hierarchy problem [38,39] and greatly hinders the testability of the mechanism.…”

Radiative neutrino masses, lepton flavor mixing and muon $g-2$ in a leptoquark model

“…These facts are in contradiction with the SM and strongly call for new physics beyond the SM. Usually, some new heavy particles are introduced to generate the tiny neutrino masses at the tree level, such as right-handed neutrinos, SU (2) L -triplet Higgs and SU (2) L -triplet fermions in the type-I [3][4][5][6][7], type-II [8][9][10][11][12][13] and type-III [14,15] seesaw mechanisms, respectively. An alternative and interesting way to naturally generate the tiny neutrino masses is via radiative corrections [16][17][18] (see.…”

Leptons and other forces of Nature

“…The Majorana nature is associated with the indistinguishability of particle and antiparticle states for neutral fermions like neutrinos [29,30]. The origin of the neutrino mass is associated with the seesaw mechanism [31][32][33][34][35][36][37][38][39][40][41][42][43] which in turn solely depends on the Majorana nature of the neutrinos. It is hypothesised that the seesaw mechanism occurs at a very high energy scale (E ∼ 10 14 Gev) and it is associated with heavy Majorana neutrinos.…”