Probing the twist-3 multi-gluon correlation functions by pp \to DX

TL;DR

This paper investigates the single spin asymmetry in D-meson production in polarized proton collisions to probe twist-3 triple-gluon correlation functions, providing new theoretical formulas and preliminary estimates based on RHIC data.

Contribution

The paper derives a new cross section formula for the twist-3 triple-gluon correlation contribution to SSA in D-meson production, differing from previous studies, and offers initial estimates using experimental data.

Findings

Derived a new formula for the triple-gluon contribution to SSA.

Identified differences from previous theoretical results.

Provided preliminary estimates based on RHIC data.

Abstract

We study the single spin asymmetry (SSA) for the D-meson production $A_N^D$ in the $pp$ collision, $p^\uparrow p\to DX$, in the framework of the collinear factorization. Since the charm quark is mainly produced through the $c\bar{c}$-pair creation from the gluon-fusion process, this is an ideal process to probe the twist-3 triple-gluon correlation functions in the polarized nucleon. We derive the corresponding cross section formula for the contribution of the triple-gluon correlation function to $A_N^D$ in $p^\uparrow p\to DX$, applying the method developed for $ep^\uparrow\to eDX$ in our previous study. As in the case of $ep^\uparrow\to eDX$, our result differs from a previous study in the literature. We will also present a simple estimate of the triple-gluon correlation functions based on the preliminary data on $A_N^D$ by RHIC.