NONPERTURBATIVE QED AND LOOP BREMSSTRAHLUNG OF NEUTRAL LEPTON PAIRS IN HEAVY-ION COLLISIONS

A simplified model of an eikonal representation for the scattering of high-Z ions is formulated, involving an IR approximation to closed fermion loops which themselves carry full radiative corrections. Signals are found for the possible production of "resonances" from such a loop when the impact-parameter-dependent electric field between the ions reaches successive thresholds on the order of m2c52h-32. Qualitative arguments are given leading to narrow widths (1/430 keV) and a prediction of peak energies in reasonable agreement with the data. An explicit enhancement factor, arising from the computation of low-frequency radiative corrections across the loop in the presence of a sufficiently strong external field, compensates the smallness of the fine-structure constant. © 1990 The American Physical Society.