Reconstruction of f (R) models with scale-invariant power spectrum

Following our previous work in [T. Qiu, JCAP 1206 (2012) [1]] Mb in this Letter, we continue our study of reconstructing f (R) modified gravity models that can be connected to a single scalar field in general relativity via conformal transformation, which lead to scale-invariant power spectrum in the early universe. With f (R) modified gravity, one does not need to introduce extra scalar, the nature of which are to be explained. Different from general nonminimal coupling theory, the behavior of the f (R) theory has been fixed by its counterpart in Einstein frame, and thus have one-to-one correspondence. Numerical plots of the functional form of f (R) as well as the evolution of R in terms of cosmic time t are also presented. (C) 2012 Elsevier BM. All rights reserved.