Gauge-invariant metric perturbations during reheating

The possible amplification of gauge-invariant metric fluctuations in the in frared sector is very important during the reheating stage of inflation. In this stage the inflaton field oscillates around the minimum of the scalar potential. The evolution for the super Hubble scales gauge-invariant metric fluctuations can be studied by means of the Bardeen parameter. For a massi ve scalar field with potential V(Phi (e)) = m(2)/2 Phi (2)(c) + Lambda with nonzero cosmological constant I find that (in the reheating regime and for super Hubble scales) the Sasaki-Mukhanov parameter oscillates with amplitu de constant such that there is not amplification of Q during reheating.