content_image/364770.jpg content_image/364769.jpg content_image/364783.jpg content_image/364782.jpg content_image/364781.jpg content_image/364780.jpg content_image/364779.jpg
<img src='content_image/364770.jpg'>

and finally we obtain 

<img src='content_image/364769.jpg'>

<img src='content_image/364783.jpg'>

For an T × R rectangle with T ≫ R , when 

resulting in 

<img src='content_image/364782.jpg'>

<img src='content_image/364781.jpg'>

we reproduce the well-known result for the L¨ uscher term by the substitution a = T/π , b = R/ 2. 

For an outstretched ellipse we have from the expansion (C9b) 

<img src='content_image/364780.jpg'>

for x < x$_{0}$ ≈ 1 . 95, where the series converges, and 

<img src='content_image/364779.jpg'>

for x > x$_{0}$ ≈ 1 . 95. They match each other pretty well, as is depicted in Fig. 2. The numerical 

