The exchange particles for the weak force are very massive (about 100 times as massive as a proton). This would lead one to expect that the weak force would

Elementary particles, also known as fundamental particles, are subatomic particles that are not made up of other particles. They are smaller than an atom and do not appear to be made up of a combination of more basic things. 
The Standard Model recognizes 17 distinct particles, including 12 fermions and five bosons.