Transverse single-spin asymmetry in the low-virtuality leptoproduction of open charm as a probe of the gluon Sivers function

TL;DR

This paper investigates the transverse single-spin asymmetry in low-virtuality open charm leptoproduction to probe the gluon Sivers function, providing predictions for experiments like COMPASS and EIC.

Contribution

It offers the first detailed predictions of asymmetries in open charm leptoproduction as a probe of the gluon Sivers function within a generalized parton model framework.

Findings

Predicted asymmetries range from 0.8% to 13% for D-mesons.

Muon asymmetries are similar to D-meson asymmetries, around 0.75% to 11%.

Upper bounds on asymmetries suggest measurable effects at future colliders.

Abstract

We study the low-virtuality inclusive leptoproduction of open charm, $p^\uparrow l\rightarrow D^0+X$ as a probe of the gluon Sivers function. We perform the analysis in a generalised parton model framework. At leading order, this process is sensitive only to the gluon content of the proton. Hence any detection of a transverse single-spin asymmetry in this process would be clear indication of a non-zero gluon Sivers function (GSF). Considering COMPASS and a future Electron-Ion Collider (EIC), we present predictions for asymmetry using fits for the GSF available in literature. Predictions for peak asymmetry values lie in the range of 0.8\% to 13\%. We also present estimates of the upper bound on the asymmetry as obtained with a maximal gluon Sivers function. Further, for the case of the Electron-Ion Collider, we evaluate the asymmetry in the muons decaying from the $D$-meson and find that the asymmetry is well preserved in the kinematics of the muons. Peak values of the muon asymmetry are close to those obtained for the $D$-meson and lie in the range $0.75\%$ to 11\%.