the scalar potential reads V $^{smooth}$( S, Φ) = κ 2 ∣ − M 2 + ( ¯ ΦΦ) 2 M 2 P ∣ + κ $^{2}$| S | 2 | Φ | $^{2}$| ¯ Φ | 2 M 4 P ( | Φ | 2 + | ¯ Φ | 2 ) , (232) M 2 P ∣$^{2}$ M 4 P where we denote by the same letter the superfield and its scalar component ( θ = 0). We remind the reader that ¯ Φ, Φ are 2 fields charged under G$_{GUT}$ . If we follow the original motivation, G$_{GUT}$ = G$_{P}$$_{S}$ and we want Φ to be non-trivially charged under the factors SU (4)$_{C}$ × SU (2)$_{R}$ in order to generate the breaking scheme G$_{P}$$_{S}$ → G$_{S}$$_{M}$ . The simplest possibility to realize this is to assign Φ to the representation ( 4 , 1 , 2 ). It is then necessary to assign ¯ Φ to its complex conjugate representation ( ¯ 4 , 1 , 2 ) so that the superpotential is invariant under G , S being necessarily an absolute gauge singlet belongs to a hidden sector. We can define two real scalar fields, s and φ , as being the relevant component of the representation of the S , Φ, ¯ Φ fields such that the potential can be rewritten [68] V $^{smooth}$( s, φ ) = κ 2 ( M 2 − φ 4 M 2 P ) 2 + 2 κ $^{2}$s2 φ 6 M 4 P . (233) This modifies the picture drastically, since now the valley φ = 0 still represents a flat direction for s , but is also a local maximum in the φ direction. As a consequence, inflation will be realized for non-vanishing values of φ , which induces the symmetry breaking during inflation. The minimum of the potential at fixed s is indeed reached for φ 2 = 4 3 M $^{2}$µ2 s 2 , for s ≫ µM , (234) which correspond to the two symmetric minima of the potential. Inside the inflationary trajectory described above, the effective one-field potential is V ( s ) = µ $^{4}$(1 − (2 / 27) µ $^{2}$M$^{2}$/s$^{4}$) in the limit s ≫ µM , a form similar to mutated hybrid inflation. The predictions of the model have been studied in [63], assuming an embedding within SUSY GUTs, that is with a unification scale of 2 × 10 16 GeV and a gauge coupling constant of ∼ 0 . 7. The normalization to the COBE data imposes the mass scales of inflation is found lower than in the F -term case µ ≃ 9 × 10 14 GeV and the cutoff M scale is found close to the reduced Planck mass M ∼ M$_{P}$ . The spectral index is then given by [63] n$_{s}$ ≃ 1 = 5 3 N$_{Q}$ ≃ 0 . 97 (for N$_{Q}$ = 60) , (235) 108