Negative coupling instability and grandunified baryogenesis

I review my recent work with Brian Greene and Thomas Roos. First I discuss the effect of a negative cross-coupling on the inflaton decay in two scalar field theories. Our main finding is a new effect, the negative coupling instability, which leads to explosive particle production and very fast inflaton decay. Then I discuss the consequences of this instability for grandunified baryogenesis models. The novel aspect of this review is an intuitive explanation of the negative coupling instability, using field trajectories in the configuration space.