Trans-Planckian Physics and Non-Commutative Inflation
  Non-commutativity of spacetime at the Planck scale may deform the usual dispersion relations. And these deformed dispersion relations could lead to the accelerating phase without a scalar field. In this paper, we have calculated the spectral index and the running of spectral index in a non-commutative inflation model. Non-commutative inflation with thermal radiation gives a scale invariant spectrum in the limit $w \to -1$ and negative running spectral index which are consistent with the WMAP 3-year results. 
Seoktae Koh