Variance and 2 point function in perturbation theory

AI Thread Summary
The discussion centers on the relationship between the statistical correlation of perturbations and the quantum 2-point function in perturbation theory. Participants question whether these concepts are equivalent, particularly in the context of vacuum fluctuations being described as Gaussian. The Bunch-Davies initial condition is mentioned as a standard for normalized fields, raising inquiries about its Gaussian nature. There is a consensus that the topic is more relevant to cosmology than quantum physics, with suggestions to report the thread for reassignment. The conversation emphasizes the importance of understanding cosmological perturbations during the early universe.
karlzr
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When we try to find the statistical correlation of some perturbation between two positions, we always calculate the quantum 2-point function. Are these two concepts really the same?
Also, people say vacuum fluctuation is gaussian. For normalized fields, we always use Bunch-Davies initial condition ##\frac{1}{\sqrt{2k}}e^{-i k \tau}##. So in which sense do we say it is gaussian?
Thanks! Any reference would be appreciated!
 
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It shouldn't have been moved to quantum physics. It is absolutely cosmology! Cosmological perturbations at very early times of the universe. I should have made it clear in the previous post.
 
Yes, I too agree that this should be moved back to cosmology.
 
I think you should try the "Report" button to get attention of somebody from the staff.
 
Still need help. Thanks!
 

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