keldysh formalism

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kleeorin
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הצטרף: 15:30 15/05/2007

keldysh formalism

שליחה על ידי kleeorin » 17:18 10/02/2013

in Mahan, the expression for G lesser is: \((1+G^r\Sigma^r )G_0^<(1+\Sigma^aG^a)+G^r\Sigma^< G^a\) which is not what we talked about before
this means that in order to identify the lesser self energy i also have to know how the retarted (advanced) self energy must look like - which is no difficult in our case but might take time in other cases. is this true?

the second order (which is what im calculatng right now) ill get \(g^<(1+g^r\Sigma^r +g^a\Sigma^a )+g^r\Sigma^< g^a\) (im almost there). but why is mahan careful with their order? order doesnt matter anymore, right?

thanks in advance

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