I am trying to work out a correlation function consisting of two spin density operators. Once I rewrite everything in 2nd quantized form, I am unsure of how to apply wicks theorem because the paul matrix spins are sandwiched between creation/annihilation operators.
If it is a regular density operator I have no problem doing this, since I don't have the Pauli spin vectors to deal with.
Hope my problem clear... any suggestions? Specifically, how to deal with the sandwiched Pauli terms