Quantum scale of inflation and particle physics of the early universe

The quantum gravitational scale of inflation is calculated by finding a sharp probability peak in the distribution function of chaotic inflationary cosmologies driven by a scalar field with large negative constant $\xi$ of nonminimal interaction. In the case of the no-boundary state of the universe this peak corresponds to the eternal inflation, while for the tunnelling quantum state it generates a standard inflationary scenario. The sub-Planckian parameters of this peak (the mean value of the corresponding Hubble constant {\mbox{\boldmathH}}\simeq 10^{-5}m_P, its quantum width \Delta{\mbox{\boldmathH}}/{\mbox{\boldmathH}}\simeq 10^{-5} and the number of inflationary e-foldings {\mbox{\boldmathN}}\simeq 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.