França, Urbano [UNESP]Rosenfeld, Rogério [UNESP]2014-05-272014-05-272002-10-01Journal of High Energy Physics, v. 6, n. 10, p. 315-329, 2002.1029-8479http://hdl.handle.net/11449/66982We explore regions of parameter space in a simple exponential model of the form V = V0 e-λ(Q/Mp) that are allowed by observational constraints. We find that the level of fine tuning in these models is not different from more sophisticated models of dark energy. We study a transient regime where the parameter λ has to be less than √3 and the fixed point ΩQ = 1 has not been reached. All values of the parameter λ that lead to this transient regime are permitted. We also point out that this model can accelerate the universe today even for λ > √2, leading to a halt of the present acceleration of the universe in the future thus avoiding the horizon problem. We conclude that this model can not be discarded by current observations. © SISSA/ISAS 2002.315-329engCosmology of Theories beyond the SMPhysics of the Early UniverseArtigo10.1088/1126-6708/2002/10/015WOS:000180552900015Acesso restrito2-s2.0-4744345726