How is Born Cross Section Related to Observed Cross Section?

[songwmailvy]

Hi everyone?

What is Born cross section?
And what is the relation between it and observed cross section?
Thank you.

 

[ofirg]

In the field I am (experimental particle physics) the term usually refers to the calculated cross section at lowest order in perturbation theory. The observed cross section should in principle be compared to the cross section calculated including all order in perturbation theory. In practice, it is compared to the cross section calculated to the highest order which is available.