Electromagnetic Leptogenesis -- an EFT-Consistent Analysis via Wilson Coefficients. Part I. Low-Scale, Non-Resonant Regime

Abstract

We analyse electromagnetic leptogenesis within the framework of an effective field theory, where the dynamics is governed by the gauge-invariant dipole operator $O_{NB}$. The Wilson coefficient $C_{NB}$ is matched at one loop and renormalisation-group (RG) evolved to the electroweak scale. After electroweak symmetry breaking we compute flavour-dependent two-body decay widths and CP asymmetries for $N\to \nu +\gamma /Z$, and solve the fully flavoured Boltzmann equations. In the $N_1$-dominated regime the freeze-out baryon asymmetry is $Y_B^{\mathrm{FO}}\lesssim 10^{-17}$, far below the observed value $Y_B^{\mathrm{obs}}\simeq 8.7\times 10^{-11}$. The suppression is structural: gauge invariance forces a Higgs insertion; therefore dipole couplings $\mu \propto v/M_{\Psi }^2$ while the matched coefficient $C_{NB}$ is loop-generated and further reduced by RG running. We note that in the quasi-degenerate limit the self-energy resonance can be operative and suggest a plausible path to $Y_B^{\mathrm{obs}}$.

36 pages, 9 figures

References in corpus (20)

• Dimension-Six Terms in the Standard Model Lagrangian
• Leptogenesis
• Resonant Leptogenesis
• Leptogenesis for Pedestrians
• Renormalization Group Evolution of the Standard Model Dimension Six Operators II: Yukawa Dependence
• The Standard Model as an Effective Field Theory
• The importance of flavor in leptogenesis
• Flavour Issues in Leptogenesis
• The Sphaleron Rate in the Minimal Standard Model
• NuFit-6.0: Updated global analysis of three-flavor neutrino oscillations
• The Standard Model cross-over on the lattice
• The Present and Future Status of Heavy Neutral Leptons
• Dipole portal to heavy neutral leptons
• Right-handed neutrino magnetic moments
• A fuller flavour treatment of N_2-dominated leptogenesis
• Probing right-handed neutrinos dipole operators
• Electromagnetic Leptogenesis
• Illuminating the dark: mono-$\gamma$ signals at NA62
• Electromagnetic leptogenesis at the TeV scale
• Flavour Covariant Formalism for Resonant Leptogenesis