Electron-positron annihilation into heavy leptons at two loops

Abstract

We calculate the NNLO QED corrections to the $C$-even part of differential cross section of $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$ process. We neglect power corrections in the electron mass and obtain the result in terms of Goncharov's polylogarithms.

Comments: 26 pages, Minor typos corrected, one figure added. Agreement with Ref. [18] of the contribution to the form factor from another flavor is stated. Results unchanged