arXiv:hep-ph/9905309·v1·High Energy Physics — Phenomenology
On the Lifetime of the pi+pi- Atom
A. Gall (Bern University)🇨🇭 · J. Gasser (Bern University)🇨🇭 · V. E. Lyubovitskij (JINR, Dubna and Tomsk University)🇷🇺 · A. Rusetsky (Bern University, JINR, Dubna and Tbilisi University)🇨🇭
Abstract
The pi+pi- atom decays -in the ground state - predominantly into two neutral pions. We present a general expression for the corresponding decay width in the framework of QCD (including photons). It contains all terms at leading and next-to-leading order in isospin breaking. The result allows one to evaluate the combination |a_0-a_2| of pi-pi S-wave scattering lengths from pi+pi- lifetime measurements, like the one presently performed by the DIRAC experiment at CERN.
Comments: 4 pages, LaTeX-file