A full analytic solution of SO(10)-inspired leptogenesis

Abstract

Recent encouraging experimental results on neutrino mixing parameters prompt further investigation on SO(10)-inspired leptogenesis and on the associated strong thermal solution that has correctly predicted a non-vanishing reactor mixing angle, it further predicts sin δ 0, now supported by recent results at ∼ 95% C.L., normally ordered neutrino masses and atmospheric mixing angle in the first octant, best fit results in latest global analyses. Extending a recent analytical procedure, we account for the mismatch between the Yukawa basis and the weak basis, that in SO(10)-inspired models is described by a CKM-like unitary transformation V L , obtaining a full analytical solution that provides useful insight and reproduces accurately all numerical results, paving the way for future inclusion of different sources of theoretical uncertainties and for a statistical analysis of the constraints. We show how muon-dominated solutions appear for large values of the lightest neutrino mass in the range (0.01-1) eV but also how they necessarily require a mild fine tuning in the seesaw relation. For the dominant (and untuned) tauon-dominated solutions we show analytically how, turning on V L V CKM , some of the constraints on the low energy neutrino parameters get significantly relaxed. In particular we show how the upper bound on the atmospheric neutrino mixing angle in the strong thermal solution gets relaxed from θ 23 41 • to θ 23 44 • , an important effect in the light of the most recent NOνA, T2K and IceCube results.

Flavor effects in leptogenesis

“…It should be added that SO(10)-inspired leptogenesis also strongly favors normally-ordered neutrino masses and that, for m 1 m sol 10 meV, it is allowed only for θ 23 in the first octant. Recently, it has been noticed [86] that for the current favored values of δ ∼ − π/2, the effective Majorana mass m ee of 0νββ decay cannot be too much lower than ∼ 10 meV. Scatter plots of the solutions in the plane m ee versus m 1 are shown in the left panel of Fig.…”

“…We refer the reader to Refs. [86,87] for a detailed discussion. Here, we just give some basic hints and results.…”

“…The yellow points are obtained imposing just successful SO(10)-inspired solutions while the blue points are a subset imposing in addition the strong thermal leptogenesis condition (orange and light blue points are for V L = I). Figure taken from Ref [86]…”

SO(10) × S4 grand unified theory of flavour and leptogenesis

“…The model predicts a normal neutrino mass ordering with a CP oscillation phase of 260 • , an atmospheric angle in the first octant and neutrinoless double beta decay with m ββ = 11 meV. We also discuss N 2 leptogenesis [77][78][79][80][81][82][83], which fixes the second right-handed neutrino mass M 2 2 × 10 11 GeV, in the natural range predicted by the model. 2 The layout of the remainder of the paper is as follows.…”

Fermion masses and mixings, Leptogenesis and Baryon number violation in Pati-Salam model

“…For studies on leptogenesis in the framework of G 224 /SO(10) see for example Refs. [38][39][40][41][42][43][44][45][46][47]. In this mechanism, the baryon asymmetry of the universe is generated by the lepton asymmetry which is initially produced dynamically and later converted into the baryon asymmetry via the (B + L)-violating sphaleron process [48] that exists in the SM.…”