Pionium lifetime corrections

Abstract

Pionium lifetime corrections are evaluated in the frameworks of constrained Bethe-Salpeter equation and chiral perturbation theory. Corrections of order $O(\alpha )$ are calculated with respect to the conventional lowest-order formula, in which the strong interaction amplitude has been calculated to two-loop order with charged pion masses. The total correction is found to be of the order of $(6.1\pm 2.0)$.

9 pages, Latex. Uses Dubna98.sty. Talk given at the Int. Workshop "Hadronic Atoms and Positronium in the Standard Model", Dubna, 26-31 May 1998. To appear in the Proceedings