5.7. The range of inflation models

Over the last fifteen years or so a great number of inflationary models have been devised, both with and without reference to specific underlying particle theories. Here I will discuss a very small subset of the models which have been introduced, just to give you a flavour of the variety. At the moment particle physics model building of inflation is undergoing a renaissance, and a detailed snapshot of the current situation can be found in the review of Lyth & Riotto. [10]

However, as we shall be discussing in the next section, observations have great prospects for distinguishing between the different inflationary models. By far the best type of observation for this purpose appears to be high resolution satellite microwave background anisotropy observations, and we are fortunate that two proposals have been approved - NASA has funded the MAP satellite [11] for launch around 2000, and ESA has approved the PLANCK satellite [12] for launch some later. These satellites should offer very strong discrimination between the inflation models I shall now discuss. Indeed, it may even be possible to attempt a more challenging type of observation - one which is independent of the particular inflationary model and hence begins to test the idea of inflation itself.