Oscillons in weakly nonlinear scalar models

In this talk we will develop a precise analytic description of oscillons — long-lived quasiperiodic field lumps — in scalar field theories with nearly quadratic potentials. These oscillons are essentially nonperturbative due to large amplitudes, and they are known to achieve extreme longevities. The proposed method is based on a consistent expansion in both the inverse width of the oscillon and the anharmonicity of the potential at strong fields, which is made accurate by introducing a field-dependent “running mass".