  We not only reconstruct the slow-roll parameters for fit to the running
spectral index from WMAP three-year data in the usual slow-roll inflation model
and noncommutative inflation model, but also investigate the evolution of these
slow-roll parameters. Requiring slow-roll inflation lasts more than 20 e-folds
after CMB scales leave the horizon suggests that the potential at the last
stage of inflation takes the form $V(\phi)=V_0(1+{\eta_c\over
2}{(\phi-\phi_c)^2\over M_p^2})$, where $\eta_c$ is a constant. A natural
mechanism to end inflation at $\phi=\phi_c$ is hybrid type inflation.

Astrophysics;High Energy Physics - Phenomenology;High Energy Physics - Theory