The eikonal approach to calculation of the multiphoton exchange   contributions to the total cross sections of \pi^+pi^- atom interaction with   ordinary atoms
  The total cross sections of interaction of relativistic \pi^+\pi^- atom with ordinary atoms are obtained in the eikonal approach, which takes into consideration all multiphoton exchange processes. Contribution of these processes strongly depends on the atom nucleus charge Z and varies from 1.5% for Titanium (Z=22) to 14% for Tantalum (Z=73) 
L. Afanasyev and O. Voskresenskaya (JINR, Dubna)