Possible antigravity regions in $F(R)$ theory?
  We construct an $F(R)$ gravity theory corresponding to the Weyl invariant two scalar field theory. We investigate whether such $F(R)$ gravity can have the antigravity regions where the Weyl curvature invariant does not diverge at the Big Bang and Big Crunch singularities. It is revealed that the divergence cannot be evaded completely but can be much milder than that in the original Weyl invariant two scalar field theory. 
Kazuharu Bamba, Shin'ichi Nojiri, Sergei D. Odintsov and Diego   S\'aez-G\'omez
hep-th astro-ph.CO gr-qc hep-ph