The modular S3 group: A simpler model for neutrinos

Aminimalistic model for leptons based on the modular group ΓN of lowest level N = 2 is presented. As opposed to the only existing model of Γ2 ∼ = S3 formulated in a SUSY framework, the only non-SM field is the modulus τ, and a generalised CP symmetry is implemented. A normal ordering for the neutrino masses is predicted. Predictions for the CP violating phases are also given: the Dirac CP phase is predicted around 1.6π, the Majorana phases lie in narrow regions near ±π. Given the reduced number of free input parameters as compared to the existing literature on modular S3, this work renews interest for a unified predictive model of quark-lepton sectors based on Γ2 ∼ = S3.