Inflaton potential reconstruction without slow roll

We describe a method of obtaining the inflationary potential fromobservations which does not use the slow-roll approximation. Rather, themicrowave anisotropy spectrum is obtained directly from a parametrizedpotential numerically, with no approximation beyond linear perturbation theory.This permits unbiased estimation of the parameters describing the potential, aswell as providing the full error covariance matrix. We illustrate the typicaluncertainties obtained using the Fisher information matrix technique, studyingthe $\lambda \phi^4$ potential in detail as a concrete example.Comment: 6 pages RevTeX file with four figures incorporated (uses RevTeX and epsf). Minor changes including extra illustrative potential reconstructio