THRESHOLD LAWS FOR THE BREAKUP OF ATOMIC PARTICLES INTO SEVERAL CHARGED FRAGMENTS

Processes with three or more charged particles in the final state exhi bit a particular threshold behavior, as inferred by the famous Wannier law for a(2e + ion) system. We formulate a general solution which det ermines the threshold behavior of the cross section for multiple fragm entation. Applications to several systems of particular importance wit h three, four, and five leptons (electrons and positrons) in the field of a charged core, and two pairs of identical particles with opposite charges, are presented. Threshold exponents for these systems are pre dicted, while some previously suggested threshold laws are revised.