Simplify the following text for a Grade 5 native English-speaking person.
Original: In grand unified theories ( GUTs ) , additional gauge bosons called X and Y bosons would exist .
Simplified: All gauge bosons are bosons , which simply means that two or more of them can exist in the same place at the same time , unlike fermions . It also means that gauge bosons have a spin of 0 or 1 .