Determination of $\ddot{I}€\ddot{I}€$ scattering lengths from measurement of $\ddot{I}{€}^{+}\ddot{I}{€}^{-}$ atom lifetime

Abstract

The DIRAC experiment at CERN has achieved a sizeable production of $\ddot{I}{€}^{+}\ddot{I}{€}^{-}$ atoms and has significantly improved the precision on its lifetime determination. From a sample of 21227 atomic pairs, a 4% measurement of the S-wave $\ddot{I}€\ddot{I}€$ scattering length difference $|a_0-a_2|=(.0.2533_{-0.0078}^{+0.0080}{|}_{\mathrm{stat}}.{}_{-0.0073}^{+0.0078}{|}_{\mathrm{syst}})M_{\ddot{I}{€}^{+}}^{-1}$ has been attained, providing an important test of Chiral Perturbation Theory.

6 pages, 6 figures