2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/190012We derive the power spectrum $\mathcal P(k)$ of the density perturbations produced during inflation up to second-order corrections in the standard slow-roll approximation for an inflaton with more than one degree of freedom. We also present the spectral index $n$ up to first-order corrections including previously missing terms, and the running ${dn}/{d\ln k}$ to leading order.11 pages, no figure. KAIST-TH 2002/01Astrophysicstext