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arXiv · 1911.09742

Probing the linearly polarized gluons in unpolarized proton with heavy-quark pair production

N. Ya. Ivanov·A. V. Efremov·O. V. Teryaev
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Abstract

We consider the azimuthal $\cos \varphi$ and $\cos 2\varphi$ distributions and the Callan-Gross ratio $R={\rm d}\sigma_L/{\rm d}\sigma_T$ in heavy-quark pair electroproduction, $lN\rightarrow l^{\prime}Q\bar{Q}X$, as probes of linearly polarized gluons in unpolarized nucleons. Our analysis shows that the azimuthal asymmetries and Callan-Gross ratio are predicted to be large and very sensitive to the contribution of the gluonic counterpart of the Boer-Mulders function, $h_{1}^{\perp g}$, describing the linear polarization of gluons inside unpolarized nucleon. In particular, the maximum values of the azimuthal distributions vary from 0 to 1 depending on $h_{1}^{\perp g}$. We conclude that future measurements of these quantities at the proposed EIC and LHeC colliders could clarify in details the proton spin decomposition puzzle.

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N. Ya. Ivanov, A. V. Efremov, O. V. Teryaev. 2019-11-21. Probing the linearly polarized gluons in unpolarized proton with heavy-quark pair production. https://doi.org/10.1088/1742-6596%2F1435%2F1%2F012011

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