Editing Nucleon (section)

===MIT bag model===
The ''MIT bag model''<ref>Chodos et al. [https://doi.org/10.1103/PhysRevD.9.3471 "New extended model of hadrons"] {{Webarchive|url=https://web.archive.org/web/20231230134936/https://journals.aps.org/prd/abstract/10.1103/PhysRevD.9.3471 |date=2023-12-30 }}, Phys. Rev. D 9, 3471 (1974).</ref><ref>Chodos et al. [https://doi.org/10.1103/PhysRevD.10.2599 "Baryon structure in the bag theory"] {{Webarchive|url=https://web.archive.org/web/20231230134924/https://journals.aps.org/prd/abstract/10.1103/PhysRevD.10.2599 |date=2023-12-30 }}, Phys. Rev. D 10, 2599 (1974).</ref><ref>DeGrand et al. [https://doi.org/10.1103/PhysRevD.12.2060 "Masses and other parameters of the light hadrons"] {{Webarchive|url=https://web.archive.org/web/20231230134817/https://journals.aps.org/prd/abstract/10.1103/PhysRevD.12.2060 |date=2023-12-30 }}, Phys. Rev. D 12, 2060 (1975).</ref> confines quarks and gluons interacting through [[quantum chromodynamics]] to a region of space determined by balancing the pressure exerted by the quarks and gluons against a hypothetical pressure exerted by the vacuum on all colored quantum fields.  The simplest approximation to the model confines three non-interacting quarks to a spherical cavity, with the [[boundary condition]] that the quark [[vector current]] vanish on the boundary. The non-interacting treatment of the quarks is justified by appealing to the idea of [[asymptotic freedom]], whereas the hard-boundary condition is justified by [[quark confinement]].

Mathematically, the model vaguely resembles that of a [[radar cavity]], with solutions to the [[Dirac equation]] standing in for solutions to the [[Maxwell equations]], and the vanishing vector current boundary condition standing for the conducting metal walls of the radar cavity. If the radius of the bag is set to the radius of the nucleon, the '''bag model''' predicts a nucleon mass that is within 30% of the actual mass.

Although the basic bag model does not provide a pion-mediated interaction, it describes excellently the nucleon–nucleon forces through the 6&nbsp;quark bag ''s''-channel mechanism using the ''P''-matrix.<ref>{{cite journal |last1=Jaffe |first1=R. L. |author1-link=Robert Jaffe (physicist) |author2-link=Francis E. Low |last2=Low |first2=F. E. |year=1979 |title=Connection between quark-model eigenstates and low-energy scattering |journal=Phys. Rev. D |volume=19 |issue=7| page=2105 |doi=10.1103/PhysRevD.19.2105 |bibcode=1979PhRvD..19.2105J }}</ref><ref>
{{cite journal |last1=Yu |last2=Simonov |first2=A. |year=1981 |title=The quark compound bag model and the Jaffe-Low ''P''-matrix |journal=[[Physics Letters B]] |volume=107 |issue=1–2 |page=1 |doi=10.1016/0370-2693(81)91133-3 |bibcode=1981PhLB..107....1S}}</ref>