Value of weak force coupling constant I'm trying to get my head around the weak force coupling constant $\alpha_w$ but getting confused by different resources. Hyperphysics suggests it is tiny compared with the strong force coupling, ~$10^-6$ times the size, but Griffiths Introduction to Elementary Particles claims it is ~$1/30$, and so five times larger than $\alpha_{EM}$, which hyperphysics gives as the usual $1/137$.
Not sure what's going wrong here, but can anyone explain it to me? Thank you!
http://hyperphysics.phy-astr.gsu.edu/hbase/forces/couple.html#c4
http://en.wikipedia.org/wiki/Weak_interaction#Properties
 A: Here are the inverses of the running coupling constants:

Looking at the 1/coupling_constant it is true that the weak comes out as 1/30 to the 1/137 of the electromagnetic. In equation 5 of this document   this factor is calculated , making as far as couplings go the weak four times stronger than the electromagnetic. BUT

What makes the interaction so weak is the large mass of the relevant gauge bosons.

The number given in hyper physics, (and in the  table of Griffith*), compares decays of baryons to get the weak number of 10^-6 to the strong. This means that the  propagator of the W boson that initiates the sigma decay is contributing to the measured weakness of the decay, reducing the effect of the coupling constant.
So the 10^-6 is comparing lifetimes, and the 1/30 is the coupling constant in front of the matrix element that will calculate the lifetime.



*

*I found a pdf scan of Griffiths which on page 55 has  for strength : 10 10^-2 10^-13 10^-42 ( strong, em, weak, gravitational) and cautions that  strength depends on context ( particularly weak)is quoted as different in other sources. What page is this 1/ 30? as it is a scan and not searchable.

