Leptogenesis, μ–τ symmetry and [formula omitted

R.N Mohapatra,S Nasri,Hai-Bo Yu

doi:10.1016/j.physletb.2005.03.082

R.N Mohapatra, S Nasri + Show 1 more

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https://doi.org/10.1016/j.physletb.2005.03.082

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Journal: Physics Letters B	Publication Date: Apr 21, 2005
Citations: 90	License type: cc-by

Affiliation: University of Maryland, College Park

Abstract

We show that in theories where neutrino masses arise from type I see-saw formula with three right-handed neutrinos and where large atmospheric mixing angle owes its origin to an approximate leptonic μ–τ interchange symmetry, the primordial lepton asymmetry of the Universe, εl can be expressed in a simple form in terms of low energy neutrino oscillation parameters as εl=(aΔm⊙2+bΔmA2θ132), where a and b are parameters characterizing high scale physics and are each of order ⩽10−2 eV−2. We also find that for the case of two right-handed neutrinos, εl∝θ132 as a result of which, the observed value of baryon to photon ratio implies a lower limit on θ13. For specific choices of the CP phase δ we find θ13 is predicted to be between 0.10–0.15.

Highlights

There may be a deep connection between the origin of matter in the Universe and the observed neutrino oscillations
This speculation is inspired by the idea that the heavy right handed Majorana neutrinos that are added to the standard model for understanding small neutrino masses via the seesaw mechanism[1] can explain the origin of matter via their decay
The mechanism goes as follows[2]: CP violation in the same Yukawa interaction of the right handed neutrinos, which go into giving nonzero neutrino masses after electroweak symmetry breaking, lead to a primordial lepton asymmetry via the out of equilibrium decay NR → l + H

Summary

INTRODUCTION

There may be a deep connection between the origin of matter in the Universe and the observed neutrino oscillations. The mechanism goes as follows[2]: CP violation in the same Yukawa interaction of the right handed neutrinos, which go into giving nonzero neutrino masses after electroweak symmetry breaking, lead to a primordial lepton asymmetry via the out of equilibrium decay NR → l + H (where l are the known leptons and H is the standard model Higgs field). This asymmetry subsequently gets converted to baryon-anti-baryon asymmetry observed today via the the electroweak sphaleron interactions[3], above T ≥ vwk (vwk being the weak scale). V, we describe a class of simple gauge models where these conditions are satisfied

INTRODUCTORY REMARKS ON LEPTON ASYMMETRY IN TYPE I SEESAW MODELS

LEPTON ASYMMETRY FOR TWO RIGHT HANDED NEUTRINOS

A B wθ13