A new method to clarify contribution of chiral magnetic effect in small collision system $p^{\uparrow} + A$ involving a transversely polarized proton

TL;DR

This paper proposes a novel experimental approach to isolate and study the contribution of the chiral magnetic effect in small proton-nucleus collision systems by analyzing electromagnetic field properties and polarization effects.

Contribution

It introduces a new experimental method using polarized proton data to distinguish CME signals from background in small collision systems.

Findings

Electromagnetic field orientation depends on proton polarization.

The correlator Δγ shows significant dependence on polarization angle.

Background contributions are canceled by comparing different collision geometries.

Abstract

In this paper, we propose a new experiment method to check contribution of chiral magnetic effect (CME). With experimental data of DIS involving transversely polarized proton, we have calculated the 3-D charge density inside the polarized proton, which is found to have a significant violation to spherical symmetry. Then we have calculated the property of electromagnetic field (E-M field) generated by a single transversely polarized proton ($p^{\uparrow}$). Based on them, the E-M field generated in small collision system $p^{\uparrow}+A$ are studied. We find that the orientation of this E-M field has a significant dependence on the polarization direction of the proton, and the correlator ($\Delta\gamma$ ) has also significant dependence on the angle between reaction plane and polarization direction. As background contribution are canceled comparing two collision geometry schemes, only contribution of CME is remained.