Inflation as a One-Loop Effect

We present an explicit example of a simple inflationary scenario where the accelerated expansion arises solely from quantum effects. We examine the most basic scalar-tensor gravity model with a single massive scalar field. Quantum gravity generates an effective scalar field potential that drives inflation. The model has the tensor-to-scalar ratio and scalar spectrum tilt consistent with the latest data for \(N > 64\) e-foldings and the scalar field mass of order \({2 \mathord{\left/ {\vphantom {2 3}} \right. \kern-0em} 3}\) Planck mass. We apply the same analysis for models with non-minimal couplings to gravity and find them strongly disfavored.