# 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.

• If you like this question you may also enjoy reading this and this Phys.SE post. – Qmechanic Mar 5 '13 at 23:22
• Proton mass is not generated by higgs field. And all hadron masses. – Asphir Dom Mar 5 '13 at 23:40
• @AsphirDom But their constituent quark particles do have mass that is generated by the higgs field. An electron has a different mass to an up quark, so what I'm asking is why this is so. – ODP Mar 7 '13 at 16:03
• Yes, i understood your question well. Just wanted to give you info that it is more complex than simple higgs picture. – Asphir Dom Mar 7 '13 at 17:12

## 1 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 ;)

• As the property of charge on particles can be partially explained by gauge theories, do you think that perhaps the property of Higgs-Field-interaction-strength could also be described by gauge theories? – ODP Mar 7 '13 at 16:06
• I don't think there is a direct link - the charges reflect a precise mathematical structure (they are rational numbers we understand), whereas the masses seem a bit random. Some physicists do work on theories where the Higgs isn't a fundamental scalar, but the "remnant" of a gauge theory that exists at a couple of TeV or so. It's like QCD: we normally see protons and other hadrons (a big mess), but at the LHC we can see the quarks and gluons (nice gauge theory). This idea is called "composite Higgs" and is an alternative to SUSY. – Vibert Mar 8 '13 at 0:11

## protected by Qmechanic♦Dec 11 '13 at 21:35

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