Perturbation Methods Problem
Consider the integral
![1965_notation.jpg](https://secure.tutorsglobe.com/CMSImages/1965_notation.jpg)
Where the notation is
![956_notation_2.jpg](https://secure.tutorsglobe.com/CMSImages/956_notation_2.jpg)
means a contour that is parallel to the real z axis, but moved down by a distance d.
Use the method of steepest descents to derive the full asymptotic expansion of I2 in the limit e → 0. You will have to treat the cases s > 0 and s < 0 separately, although much of the working is the same for each.