Electric dipole moments of leptons in the presence of Majorana neutrinos

Abstract

We calculate the two-loop diagrams that give a non-zero contribution to the electric dipole moment d l of a charged lepton l due to possible Majorana masses of neutrinos. Using the example with one generation of the Standard Model leptons and two heavy right-handed neutrinos, we demonstrate that the non-vanishing result for d l first appears in order O(m l m 2 ν G 2 F ), where m ν is the mass of the light neutrino and the see-saw type relation is imposed. This effect is beyond the reach of presently planned experiments.

Low-energy neutrino Majorana phases and charged-lepton electric dipole moments

“…The diagrams in Fig. 1 involve two Majorana mass insertions [5,8], so that the imaginary part of the amplitude associated with diagram Fig. 1(a) is given by…”

“…Here, we would like to review that, if the neutrinos are Majorana fermions, a nonzero charged lepton EDM is induced at the two-loop level (see, for example, [5,8]). The relevant two-loop diagrams that lead to a nonzero electron EDM are depicted in Fig.…”

“…In [5], the seesaw contribution to charged lepton EDMs was computed. Modulo extraordinary circumstances (see [5] for details), the estimate quoted in Eq. (IV.2) was obtained, and there was no connection between the CP-odd parameters probed in the EDM experiment and low energy neutrino CP-odd phases.…”

“…(IV.1) is the well-known type-I seesaw mechanism [4]. In [5], the seesaw contribution to charged lepton EDMs was computed. Modulo extraordinary circumstances (see [5] for details), the estimate quoted in Eq.…”

Electric dipole moment constraints on minimal electroweak baryogenesis

“…the electron EDM. This suppression is easily understood as EDMs do not violate lepton number, and so d e / G 2 F m e m 2 [8].…”