Corley-Jacobson dispersion relation and trans-Planckian inflation

In this paper we study the dependence of the spectrum of fluctuations in inflationary cosmology on possible effects of trans-Planckian physics, using the Corley-Jacobson dispersion relations as an example. We compare the methods used in our previous work with the WKB approximation, give a new exact analytical result, and study the dependence of the spectrum obtained using the approximate method of our previous work on the choice of the matching time between different time intervals. We also comment on recent work subsequent to our previous work on the trans-Planckian problem for inflationary cosmology.