In Zee QFT in a nutshell book p.418, Zee said about Quark mass vs Lepton mass $m_d/m_e$ :

  1. He first mentioned $m_d/m_e=1$ for unification scale.

  2. Then he mentioned $m_d/m_e\sim 3 $ in eq.15.

Are these two facts contradicting each other? Generally, what can one say about the Quark mass vs Lepton mass in GUT or for unification scale?

It will be helpful to comment the text below with your explanations.

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  • 1
    $\begingroup$ Mass ratio is not invariant on the change of scale, and the scale depends on the energy level, etc. This is why we need higher energy to find some phenomena in particle phyics...This is what I heard before. $\endgroup$
    – ChoMedit
    Jul 17, 2020 at 5:03
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    $\begingroup$ No contradiction; he explicitly says (3.15) is at the top-quark-mass scale, evolved down from the unification scale. Wildly unrealistic, but such was the giddy wishful thinking of the early 80s... $\endgroup$ Jul 17, 2020 at 14:19
  • $\begingroup$ what are some good refs on the mass contribution from 1-loop and from the Higgs in 45? thank you!!! $\endgroup$ Jul 25, 2020 at 23:25


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