Resonant Decay of Cosmological Bose Condensates

We present results of fully nonlinear calculations of decay of the inflaton interacting with another scalar field X. Combining numerical results for a cosmologically interesting range of the resonance parameter, q≤10⁶, with analytical estimates, we extrapolate them to larger q. We find that scattering of X fluctuations off the Bose condensate is a very efficient mechanism limiting growth of X fluctuations. For a single-component X, the resulting variance, at large q, is much smaller than that obtained in the Hartree approximation.