Undergrad How is the value of tT^2 calculated for neucleosynthesis

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The discussion centers on the calculation of the value 0.74 in the context of nucleosynthesis, specifically regarding the temperature/time relation during this era. The equation mentioned involves time, temperature, and the effective number of particle species, g*, which is noted to be 10.75 in the standard model. The original poster expresses frustration over the lack of detailed references or explanations beyond what is available on Wikipedia. They indicate a decision to abandon the current thread due to insufficient responses and have initiated a new thread for further discussion on a related topic. The conversation highlights the challenges in finding comprehensive resources on this specific aspect of nucleosynthesis.
Buzz Bloom
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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:​

tT2 EQ.png
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.
 
Last edited:
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.
I was pleased to get one useful response, and I am hoping to continue a discussion about that response.

Regards,
Buzz
 

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