Irrational constants in positronium decays

Abstract

We establish irrational constants, that contribute to the positronium lifetime at $O(\alpha )$ and $O({\alpha }^2)$ order. In particular we show, that a new type of constants appear, which are not related to Euler--Zagier sums or multiple $\zeta$ values.

Presented at 9th Workshop on Elementary Particle Theory: Loops and Legs in Quantum Field Theory, Sondershausen, 20-25 Apr 2008. 6 pages, 3 figures

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• Two-Loop Formfactors in Theories with Mass Gap and Z-Boson Production
• Heavy-quark QCD vacuum polarisation function: analytical results at four loops