How is the value of tT^2 calculated for neucleosynthesis

[Buzz Bloom]

The following quote is from the Wikipedia article

https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis#Characteristics .
The temperature/time relation in this era can be given by the equation:​

where

t is time in seconds,
T is temperature in MeV, and
g* is the effective number of particle species.
(g* includes contributions of 2 from photons, 7/2 from electron-positron pairs and 7/4 from each neutrino flavor. In the standard model g* is 10.75).​

I would much appreciate seeing a reference citation or an explanation from someone about how the value 0.74 is calculated for the nucleosynthesis era.

By the way, when I searched the internet for this information, all I could find were articles that quoted the same material from Wikipedia.

 

[Buzz Bloom]

Hi @Greg Bernhardt:

I think it is time to abandon this thread. I have the impression that there are no PF participants who are able to help me with respect to my question here.

I started a different thread to get help with respect to a different aspect of this thread.

https://www.physicsforums.com/threads/q-re-wiki-equation-for-t-x-t-2.903984​

I was pleased to get one useful response, and I am hoping to continue a discussion about that response.

Regards,
Buzz