Consistency of inflation and preheating in F(R) supergravity
  We study inflation and preheating in F(R) supergravity characterized by two mass scales of a scalar degree of freedom (scalaron): M (associated with the inflationary era) and m (associated with the preheating era). The allowed values of the masses M and m are derived from the amplitude of the CMB temperature anisotropies. We show that our model is consistent with the joint observational constraints of WMAP and other measurements in the regime where a sufficient amount of inflation (with the number of e-foldings larger than 50) is realized. In the low-energy regime relevant to preheating, we derive the effective scalar potential in the presence of a pseudo-scalar field chi coupled to the inflaton (scalaron) field phi. If m is much larger than M, we find that there exists the preheating stage in which the field perturbations delta chi and delta phi rapidly grow by a broad parametric resonance. 
Sergei V. Ketov, Shinji Tsujikawa
hep-th astro-ph.CO gr-qc hep-ph