The trouble with asymptotically safe inflation
  In this paper we investigate the perturbation theory of the asymptotically safe inflation and we find that all modes of gravitational waves perturbation become ghosts in order to achieve a large enough number of e-folds. Formally we can calculate the power spectrum of gravitational waves perturbation, but we find that it is negative. It indicates that there is serious trouble with the asymptotically safe inflation. 
Chao Fang and Qing-Guo Huang
hep-th astro-ph.CO gr-qc