We discuss the structure of parametric resonance which occurs in the process of reheating after inflation with two interacting scalar fields. It is found that, for the case of a not too large coupling constant, a quasi-homogeneous part of the second, initially subdominant scalar field may not be neglected due to its stochastic growth during inflation. This fact has strong consequences for the reheating stage: dynamics of background fields becomes chaotic after inflation -- it consists of subsequent chaotic and regular eras, and a tachyonic instability for inhomogeneous perturbations arises in the quantum reheating problem. This instability may pose a problem for the standard reheating scenario. In order to avoid it, the coupling constant should be either sufficiently small, or very large.
- Pub Date:
- April 2002
- General Relativity and Quantum Cosmology;
- High Energy Physics - Phenomenology
- Talk at the COSMION-5 conference (Moscow, 21-30 May 2001). To be published in Gravit. &