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. copyright 1997 The American Physical Society