Role of γ+γ→e++e−+e++e− in Photoproduction, Colliding Beams, and Cosmic Photon Absorption

Abstract

We consider the photon-photon channel, $\gamma +\gamma \to e^{+}+e^{-}+e^{+}+e^{-}$, with respect to the possible relevant experimental roles it plays in (i) the photoproduction process $\gamma +Z\to Z+e^{+}+e^{-}+e^{+}+e^{-}$, (ii) the colliding beam process $e^{\pm }+e^{-}\to e^{\pm }+e^{-}+e^{+}+e^{-}+e^{+}+e^{-}$, and (iii) the absorption of high-energy cosmic photons. Discussion of the first role includes calculation of rates at different energies, error estimates, and effects of screening and threshold cuts. In the second role, emphasis is placed on scale changes due to energy and angle kinematic cuts. Competition with the single-pair absorption process (i.e., $\gamma +\gamma \to e^{+}+e^{-}$) at the higher cosmic $\gamma$-ray energies ≈ ${10}^{20}$ eV is discussed in the consideration of the third role.