We present the calculation of the elastic and inelastic high--energy small--angle electron--positron scattering with a {it per mille} accuracy. PACS numbers 12.15.Lk, 12.20.--m, 12.20.Ds, 13.40.--f
A method to determine the running of alpha from a measurement of small-angle Bhabha scattering is proposed and worked out. The method is suited to high statistics experiments at e+e- colliders, which are equipped with luminometers in the appropriate angular region. A new simulation code predicting small-angle Bhabha scattering is also presented
A closed expression for the differential cross section of the large-angle Bhabha $e^+ e^-$ scattering which explicitly takes into account the leading and next-to-leading contributions due to the emission of two hard photons is presented. Both collinear and semi-collinear kinematical regions are considered. The results are illustrated by numerical calculations.
We consider small--angle electron--positron scattering in Quantum Electrodynamics. Leading logarithmic contributions to the cross--section are explicitly calculated to three loop. Next--to--leading terms are exactly computed to two loop. All the radiative corrections due to photons as well as pair production are taken into account. The impact of newly evaluated next-to-leading and higher order leading corrections is discussed and numerical results are explicitly given. The results obtained are generally valid for high and low energy $e^+e^-$ colliders. At LEP and SLC these results can be used to reduce the uncertainty on the cross--section below the per mille level. PACS numbers 12.15.Lk, 12.20.--m, 12.20.Ds, 13.40.--f
We study the single-spin asymmetry, $A_N(t)$, arising from Coulomb-nuclear interference (CNI) at small 4-momentum transfer squared, $-t=q^2$, aiming at explanation of the recent data from the PHENIX experiment at RHIC on polarized proton-nucleus scattering, exposing a nontrivial $t$-dependence of $A_N$. We found that the failure of previous theoretical attempts to explain these data, was due to lack of absorptive corrections in the Coulomb amplitude of $pA$ elastic scattering. Our prominent observation is that the main contribution to $A_N(t)$ comes from interference of the amplitudes of ultra-peripheral and central collisions.