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Fermi coupling constant 
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#1
Nov1712, 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? 


#2
Nov1812, 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.



#3
Nov1812, 11:11 AM

P: 6

yes it does thanks. natural units are annoying



#4
Nov2012, 12:19 PM

Sci Advisor
HW Helper
PF Gold
P: 2,026

Fermi coupling constant
You can use the conversion constant 1=192.33 MeVfm



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