Exponential Quintessence and the End of Acceleration

Recent observations indicate that the universe’s expansion has been accelerating of late. But recent theoretical work has highlighted the difficulty of squaring acceleration with the underlying assumptions of string theory, disfavoring most models of quintessence. because they predict eternal acceleration. We show that one of the simplest and most motivated quintessence models described by an exponential potential can produce the acceleration needed to explain the data while also predicting only a finite period of acceleration, consistent with theoretical paradigms. This model is no more tuned than the canonical tracking quintessence models.