Two-loop negative-dimensional integration

We evaluate a two-loop diagram, with propagators raised to an integer power p in 4p dimensions. For p<0 the negative-dimensional integration algorithm of Halliday and Ricotta gives integer results. For p<0 the use of Gegenbauer polynomials gives results involving ζ(3). An asymptotic expansion is derived for large negative dimensions and found to give highly accurate results at small positive dimensions, confirming the consistency of the methods. (orig.)