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Hadronic Atoms in QCD

J. Gasser·V. E. Lyubovitskij·A. Rusetsky
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Abstract

We propose a non relativistic effective Lagrangian approach to study hadronic atom observables in the framework of QCD (including photons). We apply our formalism to derive a general expression for the width of the pi+pi- atom decaying into two neutral pions. It contains all terms at leading and next-to-leading order in isospin breaking. The result allows one to evaluate the combination a0-a2 of pi-pi S-wave scattering lengths from pi+pi- atom lifetime measurements, like the one presently performed by the DIRAC expeiment at CERN.

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J. Gasser, V. E. Lyubovitskij, A. Rusetsky. 1999-10-27. Hadronic Atoms in QCD. https://arxiv.org/abs/hep-ph/9910524

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