Spontaneous CP violation in A4 flavor symmetry and leptogenesis

Y. H. Ahn, Sin Kyu Kang, C. S. Kim

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)


We propose a simple renormalizable model for the spontaneous CP violation based on SU(2)L×U(1)Y×A4 symmetry in a radiative seesaw mechanism, which can be guaranteed by an extra Z 2 symmetry. In our model CP is spontaneously broken at high energies, after the breaking of flavor symmetry, by a complex vacuum expectation value of the A4 triplet and gauge-singlet scalar field. We show that the spontaneously generated CP phase could become a natural source of leptogenesis, and also investigate CP violation at low energies in the lepton sector and show how the CP phases in the Pontecorvo-Maki-Nakagawa-Sakata formalism could arise through a spontaneous symmetry-breaking mechanism. As a numerical study, interestingly, we show that the normal mass hierarchy favors relatively large values of θ13, large deviations from maximality of θ23<π/4, and the Dirac-CP phase 0 ≤δ CP≤50 and 300 ≤δCP≤360. For the inverted hierarchy case, the experimentally measured values of θ13 favors θ23>π/4 and discrete values of δCP around 100, 135, 255, and 300. Finally, with a successful leptogenesis our numerical results give more predictive values on the Dirac CP phase: for the normal mass hierarchy 1 δCP 10 and for inverted one δCP∼100, 135, 300.

Original languageEnglish
Article number113012
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number11
Publication statusPublished - 2013 Jun 25

All Science Journal Classification (ASJC) codes

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


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