, in particular in stochastic processes
, the value of a correlation function r
) is the correlation
between random variables Xs
, where the indices s
are often either points in time or physical locations.
A caveat, though, in quantum field theory, we sometimes have nonpositive states and in that case, a probabilistic interpretation makes no sense. At any rate, even in ordinary quantum field theory, we need to work with quantum probability instead of classical probability.
This is a stub article. Ideally, it will make clear that the correlation functions in astronomy, financial market analysis, etc., are all instances of the same idea; therefore, a disambiguation page is not what this should be.