Washout Dynamics and Baryon Asymmetry from Nonlinear Neutrino Physics: Nonlinear Neutrino Effects in the Thermal History of the Early Universe

We investigate the consequences of a nonlinear modification of the Standard Model Lagrangian of the form [Formula: see text] where [Formula: see text] parameterizes deviations from linear field dynamics and [Formula: see text] sets the characteristic energy scale of the deformation. Such a modification induces small but systematic corrections to neutrino mass generation, washout rates, and CP-violating asymmetries within the seesaw and Weinberg-operator frameworks. We derive the corresponding mo