Achievements

arXiv:2512.10444 -- Submitted on 11 December, 2025
Link: https://arxiv.org/abs/2512.10444

Author:
Rin Takada (UTokyo)

Title:
Electromagnetic leptogenesis — an EFT-consistent analysis via Wilson coefficients. Part III. Probing light-neutrino masses and low-energy observables

Summary:
Building on the resonant electromagnetic leptogenesis framework developed in Part II, we analyse, within an effective field theory, the impact of the electromagnetic dipole operator responsible for generating the baryon asymmetry of the Universe (BAU) on light neutrino masses and low-energy observables. In the parameter region where successful BAU generation is achieved, we show that the light Majorana neutrino masses radiatively induced by the electromagnetic dipole operator are sufficiently small compared with the neutrino mass scale inferred from observations. We further consider the generation and renormalisation-group evolution of the charged-lepton dipole operator and evaluate low-energy observables such as μ→eγ, the electron electric dipole moment, and (g−2)_{μ}​. We find that all of these effects lie well below current experimental sensitivities, demonstrating that electromagnetic leptogenesis formulated within EFT is robust against constraints from low-energy measurements.

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.

JHEP12(2025)010 – Published on 01 December, 2025 (arXiv: 2509.07698)
Link: https://link.springer.com/article/10.1007/JHEP12(2025)010

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 on 25 June, 2025 (arXiv:2501.10148)
Link: 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.