[Physics] Why do some particles have a greater mass than others


The property of mass that almost every particle possesses comes from the Higgs Field. It is this field, which permeates all of space, that particles interact with and hence obtain mass.

But why do some particles have a higher mass if they are all interacting with the same Higgs Field? One would suspect that they'd all have the same mass, but there must be some property of a particular particle that makes it interact with the field in a different way, thereby giving it mass.

Best Answer

The full answer is unknown, i.e. nobody can tell you why the electron is only 0.00484... times as heavy as the muon. In fact, all interactions of massive particles (leptons) with the Higgs are of the same form (called a 'Yukawa interaction'), but for every particle, there is a different constant of proportionality ('Yukawa coupling constant'). For completeness, you can find the mathematical description here. (For the quarks, this is essentially the 'CKM matrix'.)

So the problem of different masses is equivalent to asking why some particles interact more strongly or weakly with the Higgs, although that doesn't help you much.

So the take-home message is: there is no accepted theory of physics that predicts the masses of particles in the Standard Model. If you find such a theory (or a partial theory), you can be sure to win a Nobel Prize, so good luck ;)