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Fermi coupling constant

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Nov17-12, 11:26 PM
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
[itex]\Gamma = 1/\tau = G^2E_0^5/30\pi^3[/itex]
with [itex]E_0 = 1.81[/itex]MeV and [itex]\tau log 2 = 71[/itex] sec. they get [itex]G\approx 10^{-5}/m^2_N[/itex]. 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?
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Nov18-12, 03:05 AM
P: 328
Actually, to have the right dimension, is [itex]\Gamma=\hbar/\tau[/itex]. If you plug all the numbers considering that the calculation gives the correct answer.
Nov18-12, 11:11 AM
P: 6
yes it does thanks. natural units are annoying

Meir Achuz
Nov20-12, 12:19 PM
Sci Advisor
HW Helper
PF Gold
P: 2,026
Fermi coupling constant

You can use the conversion constant 1=192.33 MeV-fm
Nov20-12, 02:36 PM
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Bill_K's Avatar
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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