Triplet production by a polarized photon beam on a polarized electron target

TL;DR

This paper calculates polarized and unpolarized observables in triplet photoproduction on electrons, providing analytical distributions and exploring the process's potential for measuring photon beam polarization.

Contribution

It presents analytical formulas for polarization observables in triplet photoproduction, including the effects of different polarization states and the influence of specific Feynman diagrams.

Findings

Derived analytical distributions over key kinematic variables.

Analyzed the impact of polarization states on observables.

Estimated the use of the process for measuring photon polarization.

Abstract

Polarized and unpolarized observables in the process of the triplet photoproduction on a free electron, $\gamma +e\to e+e+e$, have been calculated in the laboratory system. These observables are calculated in the approximation when the Borsellino and $\gamma -e$ diagrams are taken into account. Using the method of the invariant integration over the produced electron-positron pair variables, the different distributions were obtained in the analytical form. We obtain the double distribution over the $q^2$ (the square of the four-momentum transfer to the recoil electron) and $Q^2$ (the created $e^+e^-$-pair invariant mass squared) variables, and single distributions over $q^2$ or $Q^2$ variables. We consider the following cases: unpolarized particles, the photon beam is linearly polarized and circularly polarized photon beam interacts with a polarized electron target. The influence of the $\gamma -e$ terms on the calculated observables has been investigated. The possibility to use this process for the measurement of the circular polarization of the high-energy photon beam is also considered. The numerical estimations of various polarization observables have been done.