Quantum origin of the early inflationary universe

We give a detailed presentation of a recently proposed mechanism of generating the energy scale of inflation by loop effects in quantum cosmology. We discuss the quantum origin of the early inflationary Universe from the no-boundary and tunnelling quantum states and present a universal effective action algorithm for the distribution function of chaotic inflationary cosmologies in both of these states. The energy scale of inflation is calculated by finding a sharp probability peak in this distribution function for a tunnelling model driven by the inflaton field with large negative constant xi of non-minimal interaction. The sub-Planckian parameters of this peak (the mean value of the corresponding Hubble constant H similar or equal to 10(-5)mp, its quantum width Delta H/H similar or equal to 10(-5) and the number of inflationary e-foldings N greater than or equal to 60) are found to be in good correspondence with the observational status of inflation theory, provided the coupling constants of the theory are constrained by a condition which is likely to be enforced by the (quasi) supersymmetric nature of the sub-Planckian particle physics model. (C) 1997 Published by Elsevier Science B.V.