content_image/300231.jpg content_image/300233.jpg content_image/300234.jpg content_image/300232.jpg content_image/300235.jpg content_image/300236.jpg
By (3.8), we calculate 

Then we have 

where 

<img src='content_image/300231.jpg'>

<img src='content_image/300233.jpg'>

<img src='content_image/300234.jpg'>

<img src='content_image/300232.jpg'>

with the conventions z · z ′ = N ∑ i =1 z$_{i}$z ′ i for all z = ( z$_{1}$, ..., z$_{N}$ ) ∈ C $^{N}$, z ′ = ( z ′ $_{1}$, ..., z ′ N ) ∈ C $^{N}$. 

Then we have 

<img src='content_image/300235.jpg'>

where Re ( z ) is the real part of z. Now, we calculate the last term in (3.12) by using (3.10) and (3.11), we obtain 

<img src='content_image/300236.jpg'>

