Wess-Zumino inflation

In previous posts I’ve highlighted that I am engaged in developing new tools to take an inflationary model and calculate its observational consequences. In a recent paper, together with John Ellis and Nick Mavromatos at Kings, I applied some of these techniques to a particular model of inflation: the Wess-Zumino model.

This model is realistic, in the sense that it has particle physics motivation, and necessarily has two fields involved in the dynamics, as well as having one free parameter. This means that for every value of the free parameter there are a set of initial conditions, which lie on a one dimensional line in the two dimensional field space, that give rise to the observed number of e-folds of inflation. Every point on this line gives a different prediction for the observational parameters that are constrained by data.

In our paper we attempted to give a fairly complete study of the different values of the observational parameters that can arise for this model. We found some interesting things, like the fact that there are values of the free model parameter for which the multi-field dynamics are essential to allow any initial conditions to be consistent with observations, and that for these cases enhanced values of non-Gaussianity can arise. We also tried to interpret this model in a probabilistic manner, asking not just what observable signatures are possible, but also what are likely given some distribution on the space of initial conditions.

All in all it was an interesting paper to work on, and nice to be using some of the numerical tools I’ve been helping to develop. We hope to release some of these tools for others to use in the near future, so watch this space!