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What is the kinietic energy of a quark in a proton or neutron?

Anonymous Thu 20 Jan 00:37:23 2022 No.14126004 View Reply Original Report

Quoted By: >>14127536

Title says it all. In the same vain that an electron has a kinetic energy when bound to the proton, what is the kinetic energy of a quark bound to the other two quarks?

Literally cant find anything on this anywhere. Experimentally we can find the electron kinetic energy by shooting photons at hydrogen until at 13.6 eV its freed from the proton. is there a similar experiment for quarks? (I'm guessing you would be shooting electrons instead).

Anonymous

Anonymous Thu 20 Jan 2022 00:41:44 No.14126023 Report

Quoted By:

$K = [1 - \gamma] m c^2$

Anonymous

Anonymous Thu 20 Jan 2022 09:57:30 No.14127536 Report

Quoted By: >>14127878

>>14126004
>I'm guessing you would be shooting electrons instead
https://www.slac.stanford.edu/pubs/slacpubs/5500/slac-pub-5724.pdf

Anonymous

Anonymous Thu 20 Jan 2022 12:47:18 No.14127878 Report

Quoted By:

>>14127536
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very insightful anon, but is there perhaps a paper out there that shows a cross section of photon-proton interaction for the hydrogen nucleus? everything I find is for much heavier nuclei like iron or lead.

I'm particularly interested in the resonance energies of such an interaction as I imagine that a photon of a few 100 MeV would be breaking the proton into a meson/delta and neutron for example.

Anonymous

Anonymous Thu 20 Jan 2022 12:52:13 No.14127891 Report

Quoted By: >>14128057

The question doesn't have an answer (yet). The reasoning is that we lack a grand unified theory. Quark kinetic energy will be a function of the strong and weak interactions. Asking what its kinetic energy now is like asking what the kinetic energy of a proton moving at 0.99c was before special relativity. We could use classical in that case, but we'd get a nonsense answer. Likewise we can use special relativity to calculate the kinetic energy of a quark. But it'll be wrong.

Anonymous

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Anonymous Thu 20 Jan 2022 14:12:30 No.14128057 Report

Quoted By: >>14128085

>>14127891
What of the electrostatic energy between the quarks? Obviously such a system would be a three body problem that would perhaps have 3 quarks orbit about a common center with radius of 0.833 fm. I know this interpretation isn't strictly true for QM but it seems the electrostatic energy between quarks is generally ignored with considering the kinetics of inside the proton.

Does mainstream physics imagine that the quarks inside the proton and neutron as a dynamic structure where they have relativistic motion? Or do they imagine that the quarks are sitting near rest exchanging gluons back and forth?

pic not related but thought it was funny

Anonymous

Anonymous Thu 20 Jan 2022 14:20:15 No.14128085 Report

Quoted By:

>>14128057
I should have clarified. When I wrote the weak interactions, I meant electroweak since the two (electric and weak) are really the same force (or more precisely, aspects of the same general electroweak interaction).

I don't know what you mean by mainstream physics (pop or expert)? In pop physics the three valence quarks are all that exist. In real physics there is an infinite sea of quarks and virtual quarks spontaneously flickering in and out of existence via gluon exchange. (Imo this doesn't properly encapsulate what's really happening, and is rather merely an artifact of our QFT model).

Quarks and gluons are described by Parton distribution functions. Neither their location nor their energy is well defined, and they exist only probabilistically. In the proton, three specific quarks have uncharacteristically high probabilities to exist while the proton is at rest. These constitute the valence quarks and what arose out of DIS experiments (noticing that electrons were scattering elastically off seemingly point-like constituents). Rather what really happens was that it was a fluke (an expected fluke, mind you), since the electron could've scattered off the gluons or antiquarks. Such collisions are short-lived and much less likely to occur than with valence quarks.

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