Achievements

arXiv:2510.21089 -- Submitted on 27 October, 2025
Link: https://arxiv.org/abs/2510.21089

Author:
Rin Takada (UTokyo)

Title:
Electromagnetic leptogenesis — an EFT-consistent analysis via Wilson coefficients. Part II. Low-scale, resonant regime

Summary:
When electromagnetic leptogenesis is treated within the framework of effective field theory, the structural suppression identified in Part I emerges. To overcome this suppression, we follow the Pilaftsis–Underwood framework of resonant leptogenesis, in which the self-energy contributions to the CP asymmetries are resonantly enhanced, allowing for the generation of a baryon asymmetry sufficient enough to reproduce the observed value. To avoid fine-tuning, the effective field theory incorporates the Froggatt–Nielsen mechanism, demonstrating the naturalness of the extremely small values appearing in the resonance parameters.

JHEP –  Accepted on 24 October, 2025
arXiv:2509.07698 – Submitted on 9 September, 2025
Link: https://arxiv.org/abs/2509.07698

Author:
Rin Takada (UTokyo)

Title:
Electromagnetic leptogenesis — an EFT-consistent analysis via Wilson coefficients. Part I. Low-scale, non-resonant regime

Summary:
We analyse electromagnetic leptogenesis in an effective‑field‑theory framework. After matching at one loop and evolving to the electroweak scale, we compute heavy‑neutrino decay rates and flavour‑resolved CP asymmetries, and solve fully flavoured Boltzmann equations. In the non-resonant regime, the generated baryon asymmetry is structurally suppressed—by gauge-invariance-induced Higgs insertion—to a level far below the observed value, while a quasi-degenerate (resonant) limit may still offer a viable path.

Phys. Rev. D 111, 115029 – Published 25 June, 2025 (arXiv:2501.10148)
DOI: https://doi.org/10.1103/s7dp-8f59

Authors:
Kenta Hotokezaka (UTokyo), Ryusuke Jinno (KobeU), Rin Takada (UTokyo)

Title:
Leptogenesis in the presence of density perturbation

Summary:
In this study, we point out a phenomenon in which density perturbations in the early universe become sound waves and give an effect beyond linear perturbation theory on heavy particles, and we named this effect ``acoustically driven freeze-out". It was found that acoustically driven freeze-out increase the spatially averaged freeze-out values of lepton asymmetry.