This evening -- while thinking outside the confines of the standard model -- I imagined proton is a neutron with a positron. Then I googled "positron inside neutron" to see if the concept had be considered previously. I found this letter to the editor of Nature from 1933 where it is proposed by N. Thon. You can read this bit without paying:
http://www.nature.com/nature/journal/v131/n3320/abs/131878c0.html *"The neutron is usually looked upon as an aggregate of a proton and an electron. If it were so, there ought to be a strong tendency for hydrogen atoms to be converted spontaneously into neutrons, and the number of neutrons present in the universe should be much higher than it is assumed to be. I suggest that the proton be considered as an aggregate of a neutron and a positron. The neutron would be looked upon as an elementary material corpuscle without electric charges altogether. The proton would be able to dissociate into a neutron and a positron."* * * If you click the download button you get to read a little bit more: http://www.nature.com/nature/journal/v131/n3320/pdf/131878c0.pdf *"The very small number of neutrons and positrons met with in the universe would then be easily explained by the fact that the dissociation of protons requires a large quantity of energy and is by no means spontaneous."* ** I haven't read the full article so I don't know if the following refinement is contained in it. I propose a distinction between isolated protons and proton pairs. An isolated proton has a very large energy of dissociation but when protons are in pairs one is "willing" to spontaneously dissociate. This conception of the proton appears consistent with what is known about the formation of a deuteron from diproton: diproton ---> deuteron + positron + neutrino. Futhermore, let us propose that the dissociation of one proton within a proton association may happen with some regularity even when the protons are not tightly bound by nuclear forces. In other words a loosely associated proton pair can transform into a loosely associated proton and neutron couple through the emission of a positron. Subsequently proton and neutron couple come together to form a deuteron. This is cold fusion. Harry
