Pseudo-Dirac neutrinos in the new standard model

André De Gouvêa*, Wei Chih Huang, James Jenkins

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

57 Scopus citations


The addition of gauge-singlet fermions to the standard model Lagrangian renders the neutrinos massive and allows one to explain all that is experimentally known about neutrino masses and lepton mixing by varying the values of the Majorana mass parameters M for the gauge singlets and the neutrino Yukawa couplings λ. Here we explore the region of parameter space where M values are much smaller than the neutrino Dirac masses λv. In this region, neutrinos are pseudo-Dirac fermions. We find that current solar data constrain M values to be less than at least 10-9eV, and discuss the sensitivity of future experiments to tiny gauge-singlet fermion masses. We also discuss a useful basis for analyzing pseudo-Dirac neutrino mixing effects. In particular, we identify a simple relationship between elements of M and the induced enlarged mixing matrix and new mass-squared differences. These allow one to directly relate bounds on the new mass-squared differences to bounds on the singlet fermion Majorana masses.

Original languageEnglish (US)
Article number073007
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number7
StatePublished - Oct 14 2009

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


Dive into the research topics of 'Pseudo-Dirac neutrinos in the new standard model'. Together they form a unique fingerprint.

Cite this