# Has the number of particle types changed in the GUT era and after?

The Wikipedia article on Grand Unified Theory says:

"GUT models predict that at even higher energy, the strong interaction and the electroweak interaction will unify into a single electronuclear interaction. This interaction is characterized by one larger gauge symmetry and thus several force carriers, but one unified coupling constant".

Do I understand correctly that in the GUT era there were as many types of force carriers, that is, bosons, as after this era (although after that some bosons simply acquired mass)? That is, after breaking the symmetry and separating different forces, the number of particle types did not change?

• Yes, if by advancing "era" you mean decreasing energy. The 24 gauge bosons are always there, assuming the theory holds, but the broken ones are so massive their minute effects have not been confirmed yet. – Cosmas Zachos Dec 30 '20 at 23:29
• How many particle types were there in the GUT era, and how many are there after? – Арман Гаспарян Dec 31 '20 at 6:12

I will write this comment as an answer, because comments have a way of disappearing:

Yes, if by advancing "era" you mean decreasing energy. The 24 gauge bosons are always there, assuming the theory holds, but the broken ones are so massive their minute effects have not been confirmed yet.

It means that if the hypothesis that GUT is the correct theory for describing particle interactions, the number of gauge bosons is the same before and after symmetry breaking of the GUTS.

BUT the masses after symmetry breaking of the broken "new bosons" are too large to be detected in experimet. In usual reactions calculated with just SU(3)xSU(2)xU(1), higher order loops with these large mass GUT bosons will give very small numbers (due to the large mass in the propagator denominator) , and will not have detectable effects when comparing with measurements.