There should be a family of resonances of this type of meson. When neutrons and protons swap identities in a nucleus, the neutron with (2 downs and 1 up quark), becomes a proton with (2 ups and 1 down). The net effect is a down changes to an up, and a W^- is emitted. The W minus decays almost immediately to an electron, and an electron-type antineutrino. This would be free neutron decay to make hydrogen atoms...(like around a nuclear reactor, or bomb).
However, in the nucleus, W⁺'s, and W^-'s are snapped up by nearby nucleons, in an incessant flutter of virtual -particle identity shifts.. like Cinderella, as long as they disappear before Heisenberg Uncertainty strikes..(midnight)...no one's the wiser. That all changes when an intruding particle imparts a fluttering W with sufficient kinetic energy to promote the virtual particle into the real world. One such promotion views the W⁺ as an up/anti-down. If the kinetic energy of the incoming particle is suficiently high enough, left over energy from the first virtual-real promotion can create a secondary particle/anti-particle pair...(Z⁰) in a classic neutral current. This newly formed Z couples to all the members of the Standard Model, as Z's are universal in their coupling.
So, we should see a Z⁰ as a strange/anti-strange quark coupled to the W⁺, ...as a charm/anti-charm quark coupled to a W⁺,...as a bottom/anti-bottom quark coupled to a W⁺,....and as a top/anti-top quark coupled to a W⁺. Cross-sections tend to vary as the square of the energy for nucleon/Z interactions, so I think a quartet will appear here. (guillotine drops on head here.) Be interesting to see a fit on Lisi's E(8).


Phenomenologically, since they should appear with increasing intensity at higher energies..(or temperatures)...such as in a core collapse supernova, they ought to sap kinetic energy from the incoming core matter with a higher probability in the interior of the star. That should lead to kinematic collapse braking, bounce, and a hydrodynamical rebound mechanism. As always, being a weak interaction, a polar preference due to parity effects will display in the morphology of the subsequent expanding fireball, and directionality of any pulsar ejection.
Betcha a hot fudge sundae to the first two takers that there'll be four of these new babies, and that they'll fit on Lisi's E(8)...that's a separate box of Crackerjacks....and another guillotine blade for my head. Ciao. pete

EDIT: Actually, thinking about it, it seemed odd to have four....there should be six in accordance with the Standard Model...the other two would be particularly sharp,or narrow resonances as they should be W⁺ coupled with Z as down,anti-down, and W⁺ coupled with Z as up/anti-up, and the collisions are loaded with up and downs to begin with. A retooling of the search algorithms in UA1 or Fermilab might have them already sitting there in the data.

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A third rate theory forbids.
A second rate theory explains after the fact.
A first rate theory predicts.
A. Lomonosov