Inflationary cosmology with five dimensional SO(10)

We discuss inflationary cosmology in a five dimensional SO(10) model compactified on S¹/(Z₂×Z^'₂), which yields SU(3)_c×SU(2)_L×U(1)_Y×U(1)_X below the compactification scale. The gauge symmetry SU(5)×U(1)_X is preserved on one of the fixed points, while “flipped” SU(5)^'×U(1)^'_X is on the other fixed point. Inflation is associated with U(1)_X breaking, and is implemented through F-term scalar potentials on the two fixed points. A brane-localized Einstein-Hilbert term allows both branes to have positive tensions during inflation. The scale of U(1)_X breaking is fixed from δT/T measurements to be around 10¹⁶ GeV, and the scalar spectral index n=0.98 0.99. The inflaton field decays into right-handed neutrinos whose subsequent out of equilibrium decay yields the observed baryon asymmetry via leptogenesis.