Flipped SU(5) predicts δT/T

We discuss hybrid inflation in supersymmetric flipped SU(5) model such that the cosmic microwave anisotropy δT/T is essentially proportional to (M/MP)2, where M denotes the symmetry breaking scale and MP (=2.4×1018GeV) is the reduced Planck mass. The magnitude of M determined from δT/T measurements can be consistent with the value inferred from the evolution of SU(3) and SU(2) gauge couplings. In other words, one could state that flipped SU(5) predicts (more precisely 'postdicts') δT/T. The scalar spectral index ns=0.993±0.007, the scalar to tensor ratio satisfies r≲10−6, while dns/dlnk≲4×10−4.