Symmetries and similarities for spin orientation parameters in e^+ e^- -> ZH, Z\gamma, ZZ at SM thresholds

TL;DR

This paper analyzes the spin orientations of Z bosons in e^+ e^- collisions at SM thresholds, revealing symmetry properties and similarities in polarization parameters across different processes.

Contribution

It provides analytical expressions and symmetry insights for Z boson polarization vectors and alignment tensors at threshold energies in the Standard Model.

Findings

Polarization vectors and tensors coincide or are similar at thresholds.

Symmetry properties of spin orientation parameters are identified.

Analytical expressions for Z boson polarization are derived.

Abstract

We consider the spin orentation of the final Z bosons for the processes in the Standard Model. We demonstrate that at the threshold energies of these processes the analytical expressions for the Z boson polarization vectors and alignment tensors coincide (e^+ e^- -> ZH, Z\gamma) or are very similar (e^+ e^- -> ZZ). In addition, we present interesting symmetry properties for the spin orientation parameters.