The Flipped SU(5) model is a GUT theory which states that the gauge group is [ SU(5) × U(1) ]/ and the fermions form three families, each consisting of the representations , 10-1 and 1-5. This includes right-handed neutrinos, which are known to exist because of observed neutrino oscillations. There is also an adjoint scalar field, a 10-1 and/or called the Higgs field which acquires a VEV. This results in a spontaneous symmetry breaking from
to
and also,
, , , .
Of course, calling the representations things like and 240 is purely a physicist's convention, not a mathematician's convention, where representations are either labelled by Young tableaux or Dynkin diagrams with numbers on their vertices, but still, it is standard among GUT theorists.
