Numerical evaluation of master integrals from differential equations

Abstract

The 4-th order Runge-Kutta method in the complex plane is proposed for numerically advancing the solutions of a system of first order differential equations in one external invariant satisfied by the master integrals related to a Feynman graph. The particular case of the general massive 2-loop sunrise self-mass diagram is analyzed. The method offers a reliable and robust approach to the direct and precise numerical evaluation of master integrals.Comment: Latex, 5 pages, 4 ps-figures, uses included npb.sty, presented at RADCOR 2002 and Loops and Legs in Quantum Field Theory, 8-13 September 2002, Kloster Banz, German