Weak effects in annihilations producing spin-½ and spin-0 particle pairs

Abstract

The cross section for annihilations to spin-½ and spin-0 particle pairs is given, assuming one-photon and $W^0$ exchange. All the possible vector and axial-vector couplings are considered, as well as transverse and longitudinal polarizations of the beams, and helicity correlations of the final pair. The results provide tests for detailed structure of the $W^0$ coupling such as the possibility of derivative couplings, $\mathrm{CP}$ violation, and neutral second-class currents. Applications such as $e^{-}{e}^{+}$ annihilations to muon pairs, heavy-lepton pairs, and hadron pairs are discussed. The usefulness of longitudinally polarized storage-ring beams is also discussed.