Why neutron requires charge to become stable?

Why against Coulomb attraction, nucleus require charge?

How this charge is distributed inside nucleon (quarks)? Nucleus?

Large nuclei are believed to behave like a liquid – are nucleons freely swimming there, or maybe they are somehow clustered, like in neutron-proton(-neutron) parts?

I’m thinking of a topological soliton model of particles (concrete field structures for particles, with quantum numbers as topological charges), which doesn’t only restrict to mesons and baryons like the Skyrme model, but is an attempt to a more complete theory: which family of topological soltions would correspond to our whole particle menagerie. Extremely simple model seems to qualitatively fulfill these requirements: just real symmetric tensor field (like stress-energy tensor), but with Higgs-like potential: preferring some set of eigenvalues (different) – it can be imagined as ellipsoid field: eigenvectors are axes, eigenvalues are radii. Now e.g. simplest charges are hedgehog configurations of one of three axes and topology says there is some additional spin-like singularity required (hairy ball theorem) – we get three families of leptons etc.

This is all of nothing approach: a single discrepancy and it goes to trash. Instead it seems to bring succeeding simple answers, like for above questions:

Basic structures there are vacuum analogues of Abrikosov vortex: curve-like structure around which (“quantum phase”) two axes makes e.g. pi rotation for ½ spin. The axis along the curve can be chosen in three ways – call them electron, muon or taon spin curve correspondingly.

Now baryons would be the simplest knotted structures – like in the figure, two spin curves need to be of different type. The loop around enforces some rotation of the main axis of the internal curve – if it would be 180degrees, this axis would create hedgehog-like configuration, what corresponds to +1 charge. Locally however, such fractional rotation/charge may appear, but finally the sum has to be integer.

This picture explains why charge is required for baryon stability, that for this purpose proton can share its charge with neutron. Lengthening the charge requires energy, what makes two nucleons attracting in deuteron - by this strong short-ranged force.

Here is fresh paper about this model: http://dl.dropbox.com/u/12405967/elfld.pdf

To summarize, this simple model suggests that:

- neutron has quadrupole moment (!),

- nucleons cluster into “-n-p-“ or “-n-p-n-“ parts sharing charge,

- pairs of such clusters can couple, especially of the same type (stability of even-even nuclei),

- these clusters are parallel to the spin axis of nucleus(?).

How would you answer to above questions?

Do these suggestions sound reasonably?

Can neutron have quadrupole moment? (Shouldn’t it have dipole or quadrupole moment in quark model?)

Update: while it is obvious that proton should be lighter than neutron from the picture above, it seems far nontrivial using QCD: I've just found 4 year old news about calculating nucleon mass on Blue Gene using lattice QCD: 936MeV for both +-22 or 25MeV: http://physicsworld.com/cws/article/...rst-principles