Baryon asymmetry via leptogenesis in a neutrino mass model with complex scaling

Abstract

Baryogenesis via leptogenesis is investigated in a specific model of light neutrino masses and mixing angles. The latter was proposed on the basis of an assumed complex-extended scaling property of the neutrino Majorana mass matrix $M_{\nu }$, derived with a type-1 seesaw from a Dirac mass matrix $m_D$ and a heavy singlet neutrino Majorana mass matrix $M_R$. One of its important features, highlighted here, is that there is a common source of the origin of a nonzero ${\theta }_{13}$ and the CP violating lepton asymmetry through the imaginary part of $m_D$. The model predicted CP violation to be maximal for the Dirac type and vanishing for the Majorana type. We assume strongly hierarchical mass eigenvalues for $M_R$. The leptonic CP asymmetry parameter ${\epsilon }_1^{\alpha }$ with lepton flavor $\alpha$, originating from the decays of the lightest of the heavy neutrinos $N_1$ (of mass $M_1$) at a temperature $T\sim M_1$, is what matters here with ${\epsilon }_{2,3}^{\alpha }$, originating from the decays of $N_{2,3}$, being washed out. The light leptonic and heavy neutrino number densities (normalized to the entropy density) are evolved via Boltzmann equations down to electroweak temperatures to yield a baryon asymmetry through sphaleronic transitions. The effect of flavored vs. unflavored leptogenesis in the three mass regimes (1) $M_1<10^9$ GeV, (2) $10^9$ GeV $<M_1<$ $10^{12}$ GeV and (3) $M_1>10^{12}$ GeV are numerically worked out for both a normal and an inverted mass ordering of the light neutrinos. Corresponding results on the baryon asymmetry of the universe are obtained, displayed and discussed.

17 pages, 19 figures, effect of $N_2$ leptogenesis is added in Sec. 6, version to appear in JCAP

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• The Horizontal Symmetry for Neutrino Mixing
• Symmetry of Lepton Mixing
• Flavour-Dependent Leptogenesis with Sequential Dominance
• The importance of N2 leptogenesis
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Cited by in corpus (3)

• Generalized ${\mathbb{Z}}_2\times {\mathbb{Z}}_2$ in Scaling neutrino Majorana mass matrix and baryogenesis via flavored leptogenesis
• Baryon asymmetry and lower bound on right handed neutrino mass in fast expanding Universe: an analytical approach
• Purely Triplet Seesaw and Leptogenesis within Cosmological Bound, Dark Matter and Vacuum Stability