Pair Production in Small-Angle Bhabha Scattering

Radiative corrections due to the production of virtual as well as real soft and hard pairs in small-angle Bhabha scattering are calculated analytically. Both the collinear and the semi-collinear kinematical regions of hard pair production are considered. The calculation, within the leading and next-to-leading logarithmic approximation, provides an accuracy of O(0.1%). Numerical results show that the effects of pair production have to be taken into account for a luminosity determination accurate to O(0.1%) at LEP.