High-energy expansion of two-loop massive four-point diagrams

Differential equations and high-energy expansion of two–loop diagrams in D dimensions

New method of calculation of master integrals using differential equations and asymptotical expansion is presented. This method leads to the results exact in space-time dimension D having the form of the convergent power series. As an application of this method, we calculate the two–loop master integral for ”crossed–triangle” topology which was previously known only up to O(ǫ) order. The case w...

On the New Method of Computing Two-loop Massive Diagrams

Two - loop sunset diagrams with three massive lines

In this paper, we consider the two-loop sunset diagram with two different masses, m and M , at spacelike virtuality q2 = −m2. We find explicit representations for the master integrals and an analytic result through O(ε) in d = 4 − 2ε space-time dimensions for the case of equal masses, m = M . PACS: 11.15.-q, 12.38.Bx

Massive non-planar two-loop four-point integrals with SecDec 2.1

We present numerical results for massive non-planar two-loop box integrals entering heavy quark pair production at NNLO, some of which are not known analytically yet. The results have been obtained with the program SecDec 2.1, based on sector decomposition and contour deformation, in combination with new types of transformations. Among the new features of version 2.1 is also the possibility to ...

Two-loop self-energy diagrams worked out with NDIM

In this work we calculate two two-loop massless Feynman integrals pertaining to self-energy diagrams using NDIM (Negative Dimensional Integration Method). We show that the answer we get is 36-fold degenerate. We then consider special cases of exponents for propagators and the outcoming results compared with known ones obtained via traditional methods. PACS numbers: 02.90+p, 03.70+k, 12.38.Bx Sh...