Next-to-leading order corrections to Bhabha scattering in renormalization group approach (I). Soft and virtual photonic contributions

Soft and virtual loop photonic contributions to the second order next-to-leading QED radiative corrections to Bhabha scattering are calculated with help of the renormalization group approach. The results are in agreement with earlier calculations, where other methods were used. Scale dependence and the present theoretical accuracy of Bhabha cross section description are discussed.Comment: 12 pages, 10 Figures, elsart.cl

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.Comment: Latex. 20 page

Hadronic Cross Sections in Electron-Positron Annihilation with Tagged Photon

Events with tagged photons in the process of electron-positron annihilation into hadrons are considered. The initial state radiation is suggested to scan the hadronic cross section with the energy. QED radiative corrections are taken into account. The results for the total and exclusive cross sections are given in an analytic form. Some numerical estimates are presented.Comment: 12 pages, 2PS figures, the final journal versio