In the inflationary framework of cosmology the initial phase of rapid
expansion has to be followed by a reheating stage, which is envisioned to end
in a radiation dominated big bang. Key parameters that characterize this big
bang state are the temperature at the end of the reheating stage and the baryon
asymmetry. For general interacting theories these parameters are difficult to
obtain analytically because of the involved structure of the potential. In this
paper multifield reheating is considered for interacting theories in which the
inflaton trajectory is weakly curved. This scenario is realized in the model of
j-inflation, a particular example of modular inflation, allowing an estimate
of the reheat temperature.Comment: 15 pages, improved approximation, added reference