Eur. Phys. J. C (2026) 86: 116
https://doi.org/10.1140/epjc/s10052-025-15278-4

Regular Article - Theoretical Physics

Resonant leptogenesis in inverse see-saw framework with modular S₄ symmetry

Department of Physics, National Institute of Technology, 620015, Tiruchirappalli, India

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Received: 8 October 2025
Accepted: 29 December 2025
Published online: 5 February 2026

Abstract

We introduce a lepton mass generation and flavor mixing model, realized through a (2,3) inverse seesaw structure based on modular $S_4$ symmetry. The model employs modular forms to construct the lepton Yukawa couplings, significantly simplifying the framework by reducing redundant parameters. A detailed numerical analysis demonstrates consistency with current neutrino oscillation data, yielding specific outputs for the mixing angles and CP-violating phases. The Dirac CP phase is predicted to lie near ${\delta }_{\text{CP}}\approx \pm {90}^{\circ }$, corresponding to near-maximal leptonic CP violation. The total neutrino mass lies within $\sum m_{\nu }\approx 0.0587\text{--}0.0924$ eV, and the effective Majorana mass $|m_{\mathit{ee}}|\approx (0.002\text{--}0.02)$ eV, within reach of upcoming neutrinoless double beta decay experiments such as nEXO and AMoRE-II. The model also remains consistent with current bounds on charged lepton flavor violating processes from MEG and BaBar. We further explore resonant leptogenesis enabled by quasi-degenerate heavy neutrino states and show that the observed baryon asymmetry of the universe can be successfully generated in this scenario. The combined treatment of low-energy observables and high-scale baryogenesis demonstrates the predictivity and testability of the modular $S_4$-based ISS(2,3) framework.