2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/190494The effective equation of motion is derived for a scalar field interacting with other fields in a Friedman-Robertson-Walker background space-time. The dissipative behavior reflected in this effective evolution equation is studied both in simplified approximations as well as numerically. The relevance of our results to inflation are considered both in terms of the evolution of the inflaton field as well as its fluctuation spectrum. A brief examination also is made of supersymmetric models that yield dissipative effects during inflation.36 pages, 12 figures. Version published in the Physical Review DHigh Energy Physics - PhenomenologyGeneral Relativity and Quantum CosmologyHigh Energy Physics - Theorytext