At a future lepton collider, would it be possible to measure alpha(mZ) at greater experimental precision than what we know now? If so, would that be a way to exclude certain GUT theories by comparing the LHS and RHS expressions as you do here?
Thank you so much for the comments. "would it be possible..." Of course the measurement error would be smaller, but since it's already about 5%, I don't know if it would be easy to reduce it further... "If so,..." I think it helps in choosing a theory, but ultimately it would be nice to have direct evidence, such as proton decay observations, to point to a particular GUT...
