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Puzzle: In our standard model particle physics, are there fermionic bound states that are gauge neutral to all gauge forces?

Here we concern strong SU(3) color, electromagnetic U(1) EM, hyper U(1), and weak SU(2) forces.

It looks that a single neutron (with 3 quarks $uud$) is a bound state, neutral under electric force and strong force. But from the post Are Neutrons gauge neutral to all gauge forces?

  • the neutron has a magnetic moment so interacted with magnetic field. (This is a bit strange to me, since we can boost the Lorentz force, which can mix electric and magnetic field. So after boosting the reference frame, the electric neutral neutron can also be electric non-neutral interacting with electric field???)

  • the neutron also carries weak charge (how much?)

Are there possible candidates of fermionic bound states that are gauge neutral to all gauge forces?

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  • $\begingroup$ No such particles. As for magnetic moments, linked. Have you studied neutral electric dipoles? $\endgroup$ – Cosmas Zachos Apr 1 '20 at 15:08
  • $\begingroup$ Does the right handed neutron as a bound state count as gauge neutral to all gauge forces?? $u_Rd_Rd_R$, suppose that the Higgs condensate is zero (so right handed [SU(2) singlet] quarks cannot be paired to the left handed [SU(2) doublet] via mass term.] $\endgroup$ – annie marie heart Apr 1 '20 at 15:54

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