Determination of $ÏÏ$ scattering lengths from measurement of $Ï^+Ï^-$ atom lifetime
arXiv:1109.0569 · doi:10.1016/j.physletb.2011.08.074
Abstract
The DIRAC experiment at CERN has achieved a sizeable production of $Ï^+Ï^-$ 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 $ÏÏ$ scattering length difference $|a_0-a_2| = (.0.2533^{+0.0080}_{-0.0078}|_\mathrm{stat}.{}^{+0.0078}_{-0.0073}|_\mathrm{syst})M_{Ï^+}^{-1}$ has been attained, providing an important test of Chiral Perturbation Theory.
6 pages, 6 figures