Spin Physics through QCD Instantons

TL;DR

This paper reviews how QCD instantons influence spin physics phenomena, including semi-inclusive deep-inelastic scattering, polarized proton collisions, and P-odd pion correlations in heavy-ion collisions.

Contribution

It highlights the significant role of QCD instantons in various spin-related processes and explores their potential impact on observable asymmetries in high-energy collisions.

Findings

QCD instantons contribute notably to semi-inclusive deep-inelastic scattering.

Instantons influence polarized proton-proton scattering phenomena.

They may explain P-odd pion azimuthal correlations in peripheral heavy-ion collisions.

Abstract

We review some aspects of spin physics where QCD instantons play an important role. In particular, their large contributions in semi-inclusive deep-inelastic scattering and polarized proton on proton scattering. We also review their possible contribution in the $\mathcal{P}$-odd pion azimuthal charge correlations in peripheral $AA$ scattering at collider energies.