Several authors have argued that self-consistent $f(R)$ gravity models distinct from the cold dark matter model with a cosmological constant ($\Lambda \mathrm{CDM}$) are almost ruled out. Confronting such claims, we present a particular two-parameter $f(R)$ model that (a) is cosmologically viable and distinguishable from $\Lambda \mathrm{CDM}$, (b) is compatible with the existence of relativistic stars, (c) is free of singularities of the Ricci scalar during the cosmological evolution, and (d) allows the addition of high-curvature corrections that could be relevant for inflation.

• Received 25 February 2009

DOI:https://doi.org/10.1103/PhysRevLett.102.221101