I just read somewhere that both gluons and mesons transmit the strong force, gluons between quarks inside hadrons, but mesons between nucleons. I thought that the strong force would have one field, and one associated particle, whether inside hadrons, or between nucleons (I read somewhere else that the "nuclear force" is a "residual" of the strong force). Which is the more correct way to understand the strong and the nuclear forces and associated carriers?
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3$\begingroup$ I think you should concentrate on the color charge, which gluons carry and mesons don't, as one big distinction between them. This is a nice article. scholarpedia.org/article/Color_charge $\endgroup$– user108787Dec 3, 2016 at 23:37
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2$\begingroup$ What does "more correct" mean here? The nuclear force is the interaction between hadrons, the strong force is the interaction between quarks and gluons, and you even know all the terms like "residual strong force" to look it up yourself, so what exactly do you want to know? $\endgroup$– ACuriousMind ♦Dec 3, 2016 at 23:44
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1$\begingroup$ Do you appreciate the residual van der Waals force is underlain by electromagnetism? You may use "strong interaction" to denote both gluon mediated "color" forces inside hadrons as well as residual colorless forces outside hadrons. $\endgroup$– Cosmas ZachosDec 4, 2016 at 1:56
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1$\begingroup$ I might answer that: no gluons are not the carriers of the nuclear force: mesons such as pions effectively are. Pions, as hadrons, are bound together by the strong force, and couple to nucleons by the strong force: you may think of them as emergent out of the nucleon's quarks and gluons, but they are colorless themselves. Your basic premise that strong interactions "have one field" at all scales is not valid. $\endgroup$– Cosmas ZachosDec 4, 2016 at 12:02
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1$\begingroup$ You might say that. The strongly interacting theory, depending on the scale, looks very different: at short distances, it is QCD, a theory of quarks and gluons; at longer distances, an effective sigma model chiral lagrangian, a theory of mesons and baryons. $\endgroup$– Cosmas ZachosDec 4, 2016 at 19:55
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1 Answer
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- Gluons are the force carriers of the strong force.
- Also quarks have color charge (i.e. the take part in the strong interaction).
- Mesons are the combination of a quark and an antiquark.
- Baryons are from 3 quarks, antibaryons from 3 antiquarks. Nucleons are baryons.
The nuclear force is a residual force because it is the force between the nucleons. I.e. there is the 3 quark, bound with the strong force together. They zero out eachothers color charge, thus a nucleon has a zero net color charge. But it still has some color field around it, and it can interact strongly, similarly as two electric dipole would interact (although the forces between are more complex as the simple Coulomb formula).
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$\begingroup$ is it "force carriers" rather than "charge carriers" in the first bullet? $\endgroup$ Dec 4, 2016 at 0:21
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$\begingroup$ @AlfredCentauri I think gluons are both but I fixed. $\endgroup$– peterhDec 4, 2016 at 0:44
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1$\begingroup$ A nucleon has not "some color field around it". If you had to, you might envision a cloud of colorless pions around it. But thinking of stray gluons outside the confinement radius is unsound. $\endgroup$ Dec 4, 2016 at 2:00
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$\begingroup$ @CosmasZachos Afaik a highly simplified QFT introduction could improve this answer a lot. I tried to avoid any QM. $\endgroup$– peterhDec 4, 2016 at 7:37