Correlated curvature perturbations and magnetogenesis from the GUT gauge   bosons
  In the context of hybrid inflation at the scale of grand unification, it is shown that, if (some of) the gauge bosons of the unbroken grand unified group obtain a flat superhorizon spectrum of perturbations from inflation they can affect or even generate both the observed curvature perturbation and simultaneously produce a sizable primordial magnetic field capable of explaining galactic magnetism. The mechanism employs the vector curvaton idea for a supermassive grand unified gauge boson after the breaking of grand unification. 
Konstantinos Dimopoulos