It gets a bit more complicated than that.<p>Matt Strassler has a couple relevant articles on his blog site.<p>The first goes deeper than the 3-quark simplification.<p>&quot;What&#x27;s a proton?  First and foremost, it’s a mess.  A total mess&quot;<p><a href="http:&#x2F;&#x2F;profmattstrassler.com&#x2F;articles-and-posts&#x2F;largehadroncolliderfaq&#x2F;whats-a-proton-anyway&#x2F;" rel="nofollow">http:&#x2F;&#x2F;profmattstrassler.com&#x2F;articles-and-posts&#x2F;largehadronc...</a><p>The second digs into both protons and neutrons<p>&quot;So there are reasons to go further and describe things as I have elsewhere on this website: a proton is made from three quarks (two up quarks and a down quark), lots of gluons, and lots of quark-antiquark pairs (mostly up quarks and down quarks, but also even a few strange quarks); they are all flying around at very high speed (approaching or at the speed of light); and the whole collection is held together by the strong nuclear force&quot;<p><a href="http:&#x2F;&#x2F;profmattstrassler.com&#x2F;articles-and-posts&#x2F;particle-physics-basics&#x2F;the-structure-of-matter&#x2F;protons-and-neutrons&#x2F;" rel="nofollow">http:&#x2F;&#x2F;profmattstrassler.com&#x2F;articles-and-posts&#x2F;particle-phy...</a><p>And the third deals with neutron stability in nuclei, and specifically focuses on the stability of the neutron inside a deuteron.<p><a href="http:&#x2F;&#x2F;profmattstrassler.com&#x2F;articles-and-posts&#x2F;particle-physics-basics&#x2F;mass-energy-matter-etc&#x2F;the-energy-that-holds-things-together&#x2F;neutron-stability-in-atomic-nuclei&#x2F;" rel="nofollow">http:&#x2F;&#x2F;profmattstrassler.com&#x2F;articles-and-posts&#x2F;particle-phy...</a><p>[forgive me for combining a reply to an earlier comment you made on neutron stars]<p>We don&#x27;t know the equation of state of a neutron star; most viable models have substantial layering and an impressively busy energy-density flow.   Most models predict neutron stars to be very bright in neutrinos, although the brightness is typically greatest at the outer layers rather than from the deeper ones where one would expect a superfluid sea of degenerate neutrons to dominate almost to the exclusion of everything else (e.g. there <i>may</i> be small numbers of superconducting protons floating around in it), and mechanisms which produce the Pauli Exclusion Principle are non-negligible.   Possible mechanisms are somewhat constrained.  How the density profile goes below the superfluid layer is I think mainly speculation; there are BH-remnant-related reasons to hope for a lattice crystal or some block-like structure of subatomic particles forming an inner core.<p>JM Lattimer has a recent (2013) paper:  <a href="http:&#x2F;&#x2F;arxiv.org&#x2F;abs&#x2F;1305.3510" rel="nofollow">http:&#x2F;&#x2F;arxiv.org&#x2F;abs&#x2F;1305.3510</a>