Forbidden neutrinogenesis

TL;DR

This paper proposes a minimal leptogenesis model involving a new scalar that explains the universe's baryon asymmetry through thermal lepton behavior, linking it to neutrino CP violation.

Contribution

It introduces a novel forbidden neutrinogenesis mechanism utilizing finite-temperature effects and detailed quantum field calculations, connecting baryon asymmetry to neutrino CP phases.

Findings

Demonstrates leptogenesis in a minimal scalar framework.

Calculates CP asymmetry using Schwinger-Keldysh formalism.

Links baryon asymmetry to neutrino CP violation.

Abstract

The origin of neutrino masses can be simply attributed to a new scalar beyond the Standard Model. We demonstrate that leptogenesis can explain the baryon asymmetry of the universe already in such a minimal framework, where the electroweak scalar is favored to enhance the baryon asymmetry. Different from traditional leptogenesis, the realization here exploits the thermal behavior of leptons at finite temperatures, which is otherwise kinetically forbidden in vacuum. We present detailed calculations of the CP asymmetry in the Schwinger-Keldysh Closed-Time-Path formalism, and compute the asymmetry evolution via the Kadanoff-Baym equation. Such minimal forbidden neutrinogenesis establishes a direct link between the baryon asymmetry and the CP-violating phase from neutrino mixing, making the scenario a compelling target in neutrino oscillation experiments. Complementary probes from cosmology, flavor physics and colliders are also briefly discussed.