Damping rate of neutrinos in the singlet Majoron model

The damping rate and free path of neutrinos in the singlet Majoron model have been calculated including both finite temperature and symmetry breaking effects. The behaviour of right- and left-handed fermions are found inherently different. While the damping rates of the left-handed leptons are essentially model independent, e.g. directly applicable to the Standard Model, for the right-handed particles the rates are crucially sensitive to parameters of the scalar sector. In general, the damping rates are fairly large. The possibility of the right-handed neutrinos to penetrate deep into the broken phase in the electroweak phase transition still remains, however, for some parts of parameter space.