# Fermi coupling constant

 P: 6 i'm reading through halzen and martin's chapter 12 on the weak interaction which they calculate the fermi coupling constant form oxygen beta decay using $\Gamma = 1/\tau = G^2E_0^5/30\pi^3$ with $E_0 = 1.81$MeV and $\tau log 2 = 71$ sec. they get $G\approx 10^{-5}/m^2_N$. where m_N is the nucleon mass. i cant reproduce this number, just plugging in is way off. are there factors of c or h that i need to include?
 P: 328 Actually, to have the right dimension, is $\Gamma=\hbar/\tau$. If you plug all the numbers considering that the calculation gives the correct answer.
 P: 6 yes it does thanks. natural units are annoying
 Sci Advisor HW Helper PF Gold P: 2,026 Fermi coupling constant You can use the conversion constant 1=192.33 MeV-fm
Thanks
P: 4,160
 You can use the conversion constant 1=192.33 MeV-fm
Close. ħc = 197.326 MeV-fm.

(Much more useful than whatever it is in Joule-m! )

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