Does the Higgs field give mass to all particles or only to gauge bosons?

In summary, the Higgs field is responsible for giving particles mass in the standard model, including both fermions and bosons. However, there are some exceptions such as strongly interacting particles, which have mass due to strong interaction effects rather than the Higgs mechanism. There are also alternative theories where fermions get mass de novo and bosons get mass through the Higgs mechanism, but these have their own limitations and do not align with the established framework of the standard model.
  • #1
nonequilibrium
1,439
2
The title says it all.

I've seen an example worked out, and there mass was given to a gauge boson specifically. Also, I wouldn't know why the Higgs boson would want to give mass to the fermions, since they already have mass in the Yang-Mills theories; it's only the gauge bosons that initially lack mass whereas you would sometimes like them to be massive.

Based on that, I would expect the answer to be "the Higgs field (only) gives mass to the gauge bosons", however, I've always heard "the Higgs field gives particles mass", implying it's the origin of the mass for all particles.

So which of the two is it?

EDIT: or somewhere in between, which to me seems the most logical: strictly speaking it only gives mass to the massless gauge bosons, but it actually changes the mass of all particles.
 
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  • #2
I can write down a theory where the fermions get masses de novo, and bosons get masses via the Higgs mechanism. This theory will have some calculational problems if I want to calculate quantum corrections to it, but it's not nearly as sick as the equivalent model where boson masses are put in by hand. That theory doesn't even get out of the gate - it predicts nonsensical results (like negative probabilities) even before you get to the quantum corrections.

In that theory, one discovers that in addition to the fermion masses that were put in by hand, the fermions also get a mass from the Higgs. And semi-miraculously, this mass has to be exactly proportional to the mass that was put in from the beginning.

Faced with this, most folks decide that the simplest thing to do is to avoid this impossible coincidence and start off with massless fermions, and assume that the same Higgs that gives masses to bosons gives masses to fermions. This has some calculational benefits as well, which I alluded to above. However, this is far from the only option.
 
  • #3
mr. vodka said:
Based on that, I would expect the answer to be "the Higgs field (only) gives mass to the gauge bosons", however, I've always heard "the Higgs field gives particles mass", implying it's the origin of the mass for all particles.

So which of the two is it?

The latter. In the standard model, all fermions "start out" massless and then get mass as a result of their interaction with the Higgs field. Left-handed and right-handed fermions are treated differently by the weak force: the weak force only couples to left-handed fermions. This means that a mass term for the fermions, which must couple the left and right-handed fermions, does not respect the electroweak SU(2)xU(1) gauge symmetry and so does not appear. Instead, there is a three-particle interaction term that couples the Higgs field, the left-handed fermions, and the right-handed fermions. When the Higgs field gets a vacuum expectation value, this interaction term can be rewritten to look like a fermion mass proportional to the Higgs VEV + an interaction term between the fermion and the Higgs boson.

Actually, there's a significant caveat to "the Higgs field gives all particles mass." Many strongly interacting particles, such as the proton and neutron, would still be massive even if all quarks had zero mass. In fact most of the mass of the proton and neutron comes from strong interaction effects and not the Higgs-produced quark masses. For instance the proton weighs almost 1 GeV, and only a small fraction of this comes from the three up and down quarks that compose it, which weigh only around 5 MeV each. If that 5 MeV was reduced to 0 the proton mass wouldn't change very much.
 
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  • #4
Thank you.
 
  • #5
Vanadium 50 said:
I can write down a theory where the fermions get masses de novo, and bosons get masses via the Higgs mechanism. This theory will have some calculational problems if I want to calculate quantum corrections to it, but it's not nearly as sick as the equivalent model where boson masses are put in by hand. That theory doesn't even get out of the gate - it predicts nonsensical results (like negative probabilities) even before you get to the quantum corrections.

In that theory, one discovers that in addition to the fermion masses that were put in by hand, the fermions also get a mass from the Higgs. And semi-miraculously, this mass has to be exactly proportional to the mass that was put in from the beginning.

Faced with this, most folks decide that the simplest thing to do is to avoid this impossible coincidence and start off with massless fermions, and assume that the same Higgs that gives masses to bosons gives masses to fermions. This has some calculational benefits as well, which I alluded to above. However, this is far from the only option.

I'm afraid, this is simply not correct. You're ignoring issues of chiral symmetry. In a chiral theory, like the Standard Model, fundamental fermion masses break the gauge symmetry explicitly, causing the same sorts of problems that fundamental gauge boson masses would. But, because one of the chiral states is uncharged under the chiral force, it's possible to have an interaction between the charged fermion multiplet (in the fundamental representation), the uncharged fermion singlet, and the charged Higgs multiplet (in the anti-fundamental).

On the other hand, in a theory with chiral symmetry, fundamental fermion masses are just fine. But, in this case, there's no possible interaction term with the Higgs, as both chiral fermion states are in the fundamental (or anti-fundamental) representation, and the Higgs is as well, meaning that there's no way to construct a gauge singlet interaction term.
 

1. What is the Higgs field?

The Higgs field is a fundamental field that permeates all of space and gives particles their mass. It was first proposed by Peter Higgs in the 1960s and was later confirmed by experiments at the Large Hadron Collider (LHC) in 2012.

2. How does the Higgs field give particles mass?

The Higgs field interacts with particles through the Higgs mechanism, which gives particles their mass by slowing them down as they move through the field. This interaction is described by the Higgs boson, which is a particle that is created when the Higgs field is disturbed.

3. Does the Higgs field give mass to all particles?

Yes, the Higgs field is thought to give mass to all particles in the Standard Model of particle physics, including leptons (such as electrons and neutrinos) and quarks. However, the exact mechanism for how the Higgs field interacts with these particles is still being studied.

4. Does the Higgs field give mass to gauge bosons?

No, gauge bosons (such as photons and gluons) do not interact with the Higgs field. This is because they are described by gauge theories, which do not allow for mass-generating interactions. Instead, the masses of gauge bosons are thought to arise from a different mechanism known as spontaneous symmetry breaking.

5. Why is the Higgs field important?

The Higgs field is important because it is a crucial part of the Standard Model of particle physics, which is our current best theory for understanding the fundamental building blocks of the universe. It also helps explain the origin of mass in the universe and has played a significant role in shaping our understanding of the fundamental forces of nature.

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