where "H" represents the Hankel contour. The integrand has a cut along the real axis from zero to infinity, with the axis belonging to the lower half plane of "t". The integration starts at +∞ on the upper half plane (Im("t") > 0), circles the origin without enclosing any of the poles "t" = "µ" + 2"kπi", and terminates at +∞ on the lower half plane (Im("t") < 0). For the case where "µ" is real and non-negative, we can simply subtract the contribution of the enclosed "t" = "µ" pole: