Spin correlations in elastic $e^{+}e^{-}$ scattering in QED

Abstract

Spin correlations are carefully investigated in elastic $e^{+}e^{-}$ scattering in QED, for initially \textit{polarized} as well as \textit{unpolarized} particles, with emphasis placed on energy or speed of the underlying particles involved in the process. An explicit expression is derived for the corresponding transition probabilities in closed form to the leading order. These expressions are unlike the ones obtained from simply combining spins of the relevant particles which are of kinematic nature. It is remarkable that these explicit results obtained from quantum field theory show a clear violation of Bell's inequality at \textit{all} energies in support of quantum theory in the relativistic regime. We hope that our explicit expression obtained will lead to experiments in the manner described in the bulk of this paper by monitoring speed.