Single Spin Asymmetry through QCD Instantons

TL;DR

This paper investigates how QCD instantons can generate large single spin asymmetries in various scattering processes, aligning with experimental data and providing predictions for future collider experiments.

Contribution

It demonstrates that QCD instantons can produce significant SSA effects in SIDIS and proton-proton scattering, offering a novel explanation consistent with observed data.

Findings

Large SSA effects can be induced by QCD instantons in polarized proton scattering.

Results agree with experimental data for pion and kaon production across a wide energy range.

Predictions made for SSA in pion production at collider energies.

Abstract

We revisit the effects of QCD instantons in semi-inclusive deep inelastic scattering (SIDIS). We show that large single spin asymmetry (SSA) effects can be induced in longitudinally and transversely polarized proton targets. The results are in agreement with most of the reported data for pion and kaon production. The same effects are found to be important in polarized proton on proton scattering for both charged and chargeless pion productions. The results agree with the reported data in a wide range of \sqrt{s} = 19.4-200 GeV. We predict the SSA for \pi^\pm production in p_\uparrow p in the collider range of \sqrt{s} = 62.4-500 GeV. The backward \pi^{\pm} and \pi^0 productions for the SSA in p_\uparrow p collisions are predicted to coincide at large \sqrt{s}.