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2024-11-11

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Protons inside, electrons outside. But why not the other way around? (self.science)

submitted 8 months ago by netvor to c/science

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Every time I try to understand how forces which hold atoms and molecules together work, I find myself wanting to ask this question: why not the other way around? Could there be an atom which has electrons and neutrons inside, and protons outside?

It feels like a silly question, but is there something we know about the universe we live in that implies that this is not possible?

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[–] [email protected] 12 points 8 months ago

Strong interaction is really designed as a baryonic thing, leptons have no color charge (which is another way to say that they transform as SU(3) singlets). Leptons do not interact with gluons.
Not at tree-level anyway. See for example this list of vertices.

At loop levels, it's possible to imagine an electron decaying into neutrino+W, then W into two quarks who can then interact with gluons, but as it's down a couple of orders in perturbation theory so probably much too weak to hold a nucleus together. Not an expert in particle physics so I do not know with certainty whether a couple-of-loops interaction can have a measurable effect.