Lowest order and higher order QED calculations have been carried out for the RHIC high mass e+ e- pairs observed by PHENIX with single ZDC triggers. The lowest order QED results for the experimental acceptance are about two standard deviations larger
than the PHENIX data. Corresponding higher order QED calculations are within one standard deviation of the data.
A higher order QED calculation of the ultraperipheral heavy ion cross section for mu+ mu- pair production at RHIC and LHC is carried out. The so-called Coulomb corrections lead to an even greater percentage decrease of mu+ mu- production from perturb
ation theory than the corresponding decrease for e+ e- pair production. Unlike the e+ e- case, the finite charge distribution of the ions (form factor) and the necessary subtraction of impact parameters with matter overlap are significant effects in calculation an observable ultraperipheral mu+ mu- total cross section.
A new lowest order QED calculation for RHIC e+ e- pair production has been carried out with a phenomenological treatment of the Coulomb dissociation of the heavy ion nuclei observed in the STAR ZDC triggers. The lowest order QED result for the experi
mental acceptance is nearly two standard deviations larger than the STAR data. A corresponding higher order QED calculation is consistent with the data.
