The pion-pion scattering lengths from DIRAC

Abstract

The scattering lengths of a two pion system are the {\it golden magnitudes} to test the QCD predictions in the low energy sector. The DIRAC (PS-212) experiment at CERN will obtain a particular combination of the S-wave isospin 0 and 2 scattering lengths by measuring the lifetime of pionium, the hydrogen-like ${\pi }^{+}{\pi }^{-}$ atom. This measurement tests the accurate predictions of the Chiral Perturbation Theory. The most recent experimental results are presented.

arXiv commentTalk presented at Xth International Conference on Hadron Spectroscopy HADRON '03, August 31 -- September 6, 2003, Aschaffenburg, Germany