  We clarify classical inflaton models by considering them as effective field
theories `a la Ginzburg-Landau. In this approach, the WMAP statement excluding
the pure phi^4 potential implies the presence of an inflaton mass term at the
scale m ~ 10^{13}GeV.Chaotic, new and hybrid inflation models are studied in an
unified manner.In all cases the inflaton potential takes the form V(phi)=m^2
M_{Pl}^2 v(phi/M_{Pl}), where all coefficients in v(varphi) are of order one.If
such potential corresponds to supersymmetry breaking, the susy scale is sqrt{m
M_{Pl}}~10^{16}GeV which coincides with the GUT scale. For red tilted spectrum
new inflation turns to be favoured while for blue tilted spectrum, hybrid
inflation turns to be the best choice.In both cases, we find an analytic
formula relating the inflaton mass with r (tensor/scalar ratio) and the scalar
spectral index ns: 10^6 m/M_{Pl} = 127 sqrt{r|1-n_s|} where the numerical
coefficient follows from the WMAP amplitude. We review quantum phenomena during
inflation which contribute to relevant observables in the CMB anisotropies and
polarization and we focus on inflaton decay.The deviation from the scale
invariant power spectrum is measured by a small parameter Delta.Delta regulates
the infrared divergences too.In slow roll inflation, Delta is a simple function
of the slow roll parameters. The quantum fluctuations can selfdecay in the
inflationary expansion through processes forbidden in Minkowski. We compute the
self-decay of the inflaton quantum fluctuations during slow roll:superhorizon
fluctuations decay as eta^{Gamma} in conformal time where the new scaling
dimension Gamma is expressed in terms of the amplitude, n_s and r. we discuss
the implications for scalar and tensor perturbations as well as for non
gaussianities.
