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I'm trying to conceptualize the mechanism of which the quarks of the baryons and mesons themselves lose energy due to binding energy.

Traditionally, mass defect is explained as the net energy released from liberating the mass of the constituent particles minus the energy to separate them due to the binding energy. But my question is, why do they need to be separated? Can I not just annihilate them as they are?

According to this article: https://news.mit.edu/2019/quark-speed-proton-neutron-pairs-0220 the quarks slow down in Short-Range Correlated pairs as they have a larger volume to move in.

I was wondering if the pions/quarks have less momentum because of the increase in volume and this lower energy state is responsible for mass defect. Or a part of it?

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  • $\begingroup$ A thorough answer to this question might describe the “semi-empirical mass formula” and its various terms. If the EMC effect contributes measurably to binding energy, I think it would be in the pairing term. You can guesstimate the total pairing contribution at around 1 MeV by looking at the gap between the odd and even parabolae in the first figure of this other answer. $\endgroup$
    – rob ♦
    Commented Feb 14, 2023 at 6:01

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The term "mass defect" is useful for nuclear physics, where the constituent particles are neutrons and protons, which form quantum mechanically bound states.

For hadrons, which in current models are composed of quarks and a sea of quark antiquark and gluons there is no mainstream model where one could use the term "mass defect" because the force that binds hadrons in the strong nuclear force and Bohr type models of bound states cannot fit the data. Quantum chromodynamics is studied with lattice QCD.

The proton is also a hadron, and this is how one can image what is happening with the quarks and gluons and antiquarks composing it:

proton

Snapshot of a proton -- and imagine all of the quarks (up,down,and strange -- u,d,s), antiquarks (u,d,s with a bar on top), and gluons (g) zipping around near the speed of light, banging into each other, and appearing and disappearing. (M.Strassler 2010)

The paper you quote is studying a quantum mechanical effect in nuclei due to the number of protons and neutrons in nuclei, but this has little to do with the mass defect of the total nucleus, using the masses of protons and neutrons. Note that the EMC effect is seen in accelerator experiments, which is the only way to measure quark velocities from the high energy jets of particles observed.At most it could be a tiny correction to the measured mass defect.

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  • $\begingroup$ Hmm, okay that's informative. I still don't quite conceptually grasp where the stabilizing component or "loss" of energy comes from. I read this paper: hst-archive.web.cern.ch/archiv/HST2002/feynman/… that talks about the 5 quark baryon which is less stable. Does the ability to readily exchange mesons mean less occurrence of the 5 member baryon and thus greater stability and loss of mass? $\endgroup$
    – TheJeran
    Commented Feb 13, 2023 at 8:51
  • $\begingroup$ One has to know quantum mechanics mathematics to understand the proposed explanation of the EMC effect. The existence of new baryons is irrelevant, and in nuclear models with pion( and other hadron) exchange there is no possible explanation for the effect. I cannot find a paper with math in it that corresponds to the paper you quote, so it is still a matter of research. $\endgroup$
    – anna v
    Commented Feb 13, 2023 at 10:05
  • $\begingroup$ Hi Anna sorry to come back to this but it has still been bugging me. Is it "ok" to postulate the following: Much like how a song or music is an amalgamation of different waves and interaction (constructive and destructive) between those waves, a nucleon is the same but with the smaller quark waves and virtual gluon particles. When two nucleons fuse, they produce a new different song. It no longer makes sense to think of this song as two distinct objects as it is now a new complex wave/song. $\endgroup$
    – TheJeran
    Commented Mar 15, 2023 at 16:40
  • $\begingroup$ @TheJeran you are making up a theory out of the blue, that has no connection with the theoretical models used to study nuclear and particle physics. $\endgroup$
    – anna v
    Commented Mar 15, 2023 at 18:36

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