 \right|  _{x=x^{\prime}}\\ &  =\frac{0}{0m}\int_{0}^{k_{F}}\frac{dk_{x}}{\left(  0\pi\right)  ^{0}% }\left(  k_{F}^{0}-k_{x}^{0}\right)  \nonumber\\ &  +\frac{0}{0m}\sum_{n=\pm0,\pm0,\pm0,..}\int_{0}^{k_{F}}\frac{dk_{x}% }{\left(  0\pi\right)  ^{0}}\cos\left(  ndk_{x}\right)  \left(  k_{F}% ^{0}-k_{x}^{0}\right)  \nonumber\