FIG. 6: Shifted hybrid inflation potential of Eq. (238) for ξ > 1 / 4 (left) and 1 / 6 < ξ < 1 / 4 (right) in the reduced variable space. realized in one shifted valley, like for smooth hybrid inflation, the symmetry G is broken during inflation and no topological defect can affect the post-inflationary cosmology. This is the motivation of the model and also an implicit assumption. Note that the dynamics could impose inflation to take place in the central valley, at vanishing ψ . It would then be possible that the number of e-foldings produced after the symmetry breaking is small enough that topological defects have some influence on the CMB. This is still an open question. If inflation is realized in the y = ± 1 $_{/}$√$_{2}$$_{ξ}$ valley, it is possible to compute the full mass spectrum of the model [67]. The classical contribution to the potential is V$_{0}$ = κ 2 ˜ M $^{4}$, where ˜ M 4 = M $^{4}$(1 / 4 ξ − 1) $^{2}$. The one-loop quantum corrections appear like in the F -term case from the splitting in mass, 2 κ 2 ˜ M , between fermions and bosons of the superfield Φ , ¯ Φ. Consequently, the effective scalar potential in this valley is identical to Eq. (222) for the original F -term model replacing M by ˜ M . The CMB predictions are then derived; the scale of inflation and the spectral index are found as a function of κ , for a fixed value of β and M$_{S}$ identified as the string scale. For κ ∈ [10 − $^{2}$, 10 − $^{3}$], they are predicted in the ranges n$_{s}$ ∈ [0 . 89 , 0 . 99] and V$_{infl}$ ∈ [2 , 7] × 10 14 GeV, which is in agreement with the most recent CMB measurements [67]. The level of predicted tensor perturbations with these parameters, r < ∼ 10 − $^{5}$, is however beyond the reach of planned experiments. • Non-renormalizable terms and SUGRA effects: The analysis of the previous models driven by F -terms are based on the presence of 110