such that the action in the Einstein frame reads In order to keep canonical kinetic terms once the metric is redefined, the potential U for the new field χ now reads S E = ∫ d $^{4}$x √ − ˆ g { M 2 P 2 ˆ R + 1 2 ∂$_{µ}$χ∂ $^{µ}$χ − U ( χ ) } . (213) which is in agreement with the most recent WMAP data. The main challenge to this model is to evaluate the quantum corrections to the infla- tionary potential at high energyto evaluate if the flatness of the inflationary potential can be destabilized by them. Both the quantum gravity corrections and the quantum correc- tions due to SM particles can be evaluated, though the full quantum gravity corrections cannot be rigorously computed. It has been argued in Ref. [86] that the model is safe since The leading log method [86] as well as renormalization group (RG) methods have been implemented [588, 589] in both frames to compute corrections to V , and ξ . The corrections from SM particles to V using RG improved calculation with 2-loop beta-function are also found in Ref. [589] to be very small and do not spoil the model (see Fig. 3). However, they 96 U ( χ ) /M 4 P λ/ξ 2 ≪ 1 and d $^{2}$U/ d χ 2 ≪ M 2 $_{P}$. n$_{s}$ ≃ 1 − 8 (4 N$_{Q}$ + 9) (4 N$_{Q}$ + 3) 2 ≃ 0 . 97 , r ≃ 192 (4 N$_{Q}$ + 3) 2 ≃ 0 . 0033 , α$_{s}$ ≃ − 5 . 2 × $_{10}$− 4 , (217) ϵ ( χ ) ≃ 4 M 4 P 3 ξ $^{2}$h4 , η ( χ ) ≃ − 4 M 2 P 3 ξh 2 , ζ ≃ 16 M 4 P 9 ξ $^{2}$h4 , (216) U ( χ ) ≃ λM 4 P 4 ξ 2 [ 1 + exp ( − 2 χ √$_{6}$$_{M}$$_{P}$ )] . (215) U ( χ ) = 1 Ω( χ ) 4 λ 4 [ h $^{2}$( χ ) − v 2 ] 2 . (214) 2 At low energies, that is for small VEVs, Ω ≃ 1, h ≃ χ and the two frames are indistin- guishable. At high energies, h ∝ exp χ , and the potential tends to Once the potential is known at high energies, it is straightforward to compute the CMB predictions for the model. From Eq. (215), the slow-roll parameters read [86] which requires inflation to take place in the range h ∈ [1 . 07 − 9 . 4] M$_{P}$$_{/}$√$_{ξ}$$_{.}$ A correct normalization to the COBE data imposes ξ ≃ 5 × 10 4 √$_{λ}$$_{, and the model predicts, at the}$ classical level [86, 589],