Universal threshold for single-spin asymmetries in fixed target experiments

TL;DR

This paper identifies a universal energy threshold in the center of mass system where single-spin asymmetries in inclusive pion production begin to increase across fixed target experiments with beam energies from 13 to 200 GeV.

Contribution

It reveals a universal threshold behavior for single-spin asymmetries in fixed target experiments, independent of beam energy.

Findings

Single spin asymmetry starts to grow at a specific pion energy in the center of mass system.

The threshold energy for asymmetry growth is consistent across a wide range of beam energies.

The results suggest a universal mechanism underlying single-spin asymmetries.

Abstract

The analysis of inclusive $\pi$-meson single spin asymmetry measurements was done. It was found that the single spin asymmetry starts to grow up at the same value of the $\pi$-meson energy in the center of mass system for fixed target experiments at the beam energy range from 13 to 200 GeV.