Brane assisted quintessential inflation with transient acceleration

A simple model of quintessential inflation with the modified exponential potential e(-alpha phi)[A+(phi-phi(0))(2)] is analyzed in the braneworld context. Considering reheating via instant preheating, it is shown that the evolution of the scalar field phi from inflation to the present epoch is consistent with the observational constraints in a wide region of the parameter space. The model exhibits transient acceleration at late times for 0.96 less than or similar to A alpha(2)less than or similar to 1.26 and 271 less than or similar to phi(0)alpha less than or similar to 273, while permanent acceleration is obtained for 2.3x10(-8)less than or similar to A alpha(2)less than or similar to 0.98 and 255 less than or similar to phi(0)alpha less than or similar to 273. The steep parameter alpha is constrained to be in the range 5.3 less than or similar to alpha less than or similar to 10.8.