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Hadrons rest mass comes from gluon field?

by Herbascious J
Tags: field, gluon, hadron, hadrons, higgs, mass, quarks, rest
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Herbascious J
#19
Dec2-13, 05:48 PM
P: 77
Yes, I think I was wondering if maybe all mass can be seen as arising from massless particles and interactions, within the subatomic particles, a new layer so-to-speak (like preons). I'm assuming that would require a really big particle accelerator to blast apart quarks and leptons.

If something like that were true, that quarks and leptons had internal structure that was massless, therefore ALL mass was arising from non-massive energy. What would this mean for the Higgs? Would it no longer be necessary?
michael879
#20
Dec2-13, 06:00 PM
P: 628
Quote Quote by Herbascious J View Post
Yes, I think I was wondering if maybe all mass can be seen as arising from massless particles and interactions, within the subatomic particles, a new layer so-to-speak (like preons). I'm assuming that would require a really big particle accelerator to blast apart quarks and leptons.

If something like that were true, that quarks and leptons had internal structure that was massless, therefore ALL mass was arising from non-massive energy. What would this mean for the Higgs? Would it no longer be necessary?
The Higgs is necessary to break electroweak symmetry. Massive gauge theories break down at high energies, so they need to acquire mass from SOME high energy effect, the Higgs being the simplest. The coupling of fermions to the Higgs is something I've never understood fully. It's almost like after seeing the success of the Higgs mechanism someone just decided to tack fermions onto the theory. AFAIK there is no fundamental problem with massive fermions
michael879
#21
Dec2-13, 06:04 PM
P: 628
Quote Quote by Bill_K View Post
Sorry, chiral symmetry is a symmetry of QCD. Why would a pion condensate break electroweak symmetry?
I'm not defending him, because TBH I don't know much about QCD. However, his claim was that it is SPONTANEOUSLY broken, not explicitly. So it would have to be a symmetry of QCD in order to be spontaneously broken. Also, I have heard many people claim that QCD does in fact give some mass to something (bosons, fermions or both I don't remember), just not enough to account for experiment
kurros
#22
Dec2-13, 06:08 PM
P: 364
Quote Quote by michael879 View Post
The coupling of fermions to the Higgs is something I've never understood fully. It's almost like after seeing the success of the Higgs mechanism someone just decided to tack fermions onto the theory.
I agree, however as of last week there is direct evidence that the Higgs does indeed couple to fermions: http://atlas.ch/news/2013/higgs-into-fermions.html
michael879
#23
Dec2-13, 10:02 PM
P: 628
Quote Quote by kurros View Post
I agree, however as of last week there is direct evidence that the Higgs does indeed couple to fermions: http://atlas.ch/news/2013/higgs-into-fermions.html
lmao I'm actually part of that analysis, which is why my confusion on fermion couplings is right in the front of my mind :P

I was betting against it until we actually got results, now I need to figure out why that coupling should be there... The only argument I can think of is a type of naturalness argument where dimensionless constants are more desirable than constants with dimension (still fails miserably when those dimensionless constants are <<1)
kurros
#24
Dec2-13, 10:14 PM
P: 364
Quote Quote by michael879 View Post
lmao I'm actually part of that analysis, which is why my confusion on fermion couplings is right in the front of my mind :P
Haha, well good work with that :p.

Quote Quote by michael879 View Post
I was betting against it until we actually got results, now I need to figure out why that coupling should be there... The only argument I can think of is a type of naturalness argument where dimensionless constants are more desirable than constants with dimension (still fails miserably when those dimensionless constants are <<1)
Well, yeah, there is that argument that if non-renormalisable mass terms for the fermions were generated at some high scale as the result of integrating out some high scale physics, then those terms would vanish by the time you evolve down to the low scale, since they are irrelevant operators. Thus, the low scale physics should look renormalisable. I don't know so much about this though, my field theory knowledge is not good enough.

Edit: plus, you need SUSY or something to make the Higgs mass not sensitive to whatever this high scale stuff is...
Herbascious J
#25
Dec2-13, 11:00 PM
P: 77
Quote Quote by michael879 View Post
lmao I'm actually part of that analysis, which is why my confusion on fermion couplings is right in the front of my mind :P
Yeah!! That is very exciting!!! Thanks you guys for the great thread. This website has become my favorite site over the past few years! Cheers.
michael879
#26
Dec3-13, 08:51 AM
P: 628
Massive fermions ARE renormalizable, that's why I don't get why the Higgs is needed to "give" them mass. Unlike the W and Z fermions can have intrinsic mass!
Bill_K
#27
Dec3-13, 09:43 AM
Sci Advisor
Thanks
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P: 4,160
Quote Quote by michael879 View Post
Massive fermions ARE renormalizable, that's why I don't get why the Higgs is needed to "give" them mass. Unlike the W and Z fermions can have intrinsic mass!
A fermion mass term is like eLeR, it couples the left- and right-handed states together. But under the electroweak symmetry, eL transforms as a doublet while eR transforms as a singlet, so their product is not invariant. You need a third factor h, the Higgs, which in the Standard Model is also a doublet, so now the product h eLeR is a group invariant.
michael879
#28
Dec3-13, 09:57 AM
P: 628
Quote Quote by Bill_K View Post
A fermion mass term is like eLeR, it couples the left- and right-handed states together. But under the electroweak symmetry, eL transforms as a doublet while eR transforms as a singlet, so their product is not invariant. You need a third factor h, the Higgs, which in the Standard Model is also a doublet, so now the product h eLeR is a group invariant.
oooo thank you! I've had someone explain this to me before but I wasn't as familiar with SM gauge symmetries as I am now. That makes perfect sense: SU(1)xSU(2) gauge symmetry is violated by fermionic mass terms
dauto
#29
Dec3-13, 10:26 AM
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Quote Quote by michael879 View Post
oooo thank you! I've had someone explain this to me before but I wasn't as familiar with SM gauge symmetries as I am now. That makes perfect sense: SU(1)xSU(2) gauge symmetry is violated by fermionic mass terms
That's right. That's also why neutrinos may have a Majorana mass which is forbidden for other fermions. A majorana mass for other fields would violate the SU(1)xSU(2) gauge symmetry.
michael879
#30
Dec3-13, 09:49 PM
P: 628
Quote Quote by dauto View Post
That's right. That's also why neutrinos may have a Majorana mass which is forbidden for other fermions. A majorana mass for other fields would violate the SU(1)xSU(2) gauge symmetry.
Actually it has to do with charge conservation, nothing to do with SU(2) symmetry. Majorana mass terms violate U(1) symmetries if the corresponding fermion couples to that U(1) field
dauto
#31
Dec4-13, 11:56 AM
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P: 1,948
Quote Quote by michael879 View Post
Actually it has to do with charge conservation, nothing to do with SU(2) symmetry. Majorana mass terms violate U(1) symmetries if the corresponding fermion couples to that U(1) field
Yes, that's right. that's why most fermions cannot have a majorana mass. The right handed neutrino though is a U(1)xSU(2) singlet so it doesn't couple to any of the electroweak bosons.


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