I was really excited to read about a recent experiment at Fermilab. Here one can read the article. A dicrepency was seen between the calculated value of the muon $g-2$ factor, in the context of the standard model, and the experimental value. A truly breathtaking experiment! Finally new physics! But what is the new physics? What are the new particles? What is the new force?
Can a substructure of the muon be responsible? Does it have to be substructure? What new particles could be involved, if no substructure is involved?
EDIT What if the value that is found in experiment turns out to be truly different from the theoretical value? I'm already inclined to think that this is already the case, in all my excitment, but I should not, indeed, jump too high too soon. But suppose there comes a point in the future tyhat there is no doubt anymore. IF. What could the new physics be? Like the magnetic moment of the proton showed a value hinting to substructure (three quarks), this could also be the case for the muon. What else could be the case if substructure is not involved?
And now I see the list given below, by @G.Smith...
