= Solution
The entrance <Yukawa coupling> is proportional to the incident lepton <mass>, so the partial Higgs width into that lepton pair is proportional to its <mass> squared. With the question's masses,
$$
\frac{\Gamma_{\mu\mu}}{\Gamma_{ee}}\simeq
\left(\frac{106\ \mathrm{MeV}}{0.5\ \mathrm{MeV}}\right)^2
=\boxed{4.49\times10^4.}
$$
The same factor enhances direct s-channel <Higgs boson> formation when all other factors are held fixed. \b[The much larger <muon> Yukawa coupling motivates a <muon-collider Higgs resonance>.] Heavier <muons> also radiate less strongly in a curved orbit, but their decay lifetime makes a collider technically demanding. The resonance remains narrow, so a sufficiently small beam-energy spread is essential to retain a large fraction of the ideal peak.
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