Energy dependence of hadron polarization in $e^+e^-\to hX$ at high energies

TL;DR

This paper investigates how the polarization of hyperons and vector mesons produced in high-energy electron-positron collisions varies with energy, using perturbative QCD to model their fragmentation functions.

Contribution

It provides a detailed analysis of the energy dependence of hyperon polarization and meson spin alignment using leading twist perturbative QCD evolution.

Findings

Hyperon polarization depends on the initial quark polarization.

Vector meson spin alignment is independent of initial quark polarization.

Numerical results show distinct energy dependence patterns.

Abstract

The longitudinal polarization of hyperons in $e^+e^-$ annihilation at high energies depends on the longitudinal polarization of the quark produced at the $e^+e^-$ annihilation vertex whereas the spin alignment of vector mesons is independent of it. They exhibit very different energy dependences. We use the longitudinal polarization of Lambda hyperon and the spin alignment of $K^*$ as examples and present numerical results of energy dependences. We present the results at the leading twist with perturbative QCD evolutions of fragmentation functions at the leading order.