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

Abstract

We consider the azimuthal $\cos \phi$ and $\cos 2\phi$ distributions and the Callan-Gross ratio $R=\mathrm{d}{\sigma }_L/\mathrm{d}{\sigma }_T$ in heavy-quark pair electroproduction, $lN\to l^{\prime }Q\bar{Q}X$, 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.

arXiv comment4 pages, 4 figures, talk given at the XVIII Workshop on High Energy Spin Physics (DSPIN-19), September 2-6, Dubna

References in corpus (10)

• Time-reversal odd distribution functions in leptoproduction
• A Large Hadron Electron Collider at CERN: Report on the Physics and Design Concepts for Machine and Detector
• Transverse momentum dependence in gluon distribution and fragmentation functions
• Direct Probes of Linearly Polarized Gluons inside Unpolarized Hadrons
• Asymmetries in Heavy Quark Pair and Dijet Production at an EIC
• Linear polarization of gluons and photons in unpolarized collider experiments
• How to measure the linear polarization of gluons in unpolarized proton using the heavy-quark pair leptoproduction
• The ratio $R=\mathrm{d}{\sigma }_L/\mathrm{d}{\sigma }_T$ in heavy-quark pair leptoproduction as a probe of linearly polarized gluons in unpolarized proton
• QCD predictions for the azimuthal asymmetry in charm leptoproduction for the COMPASS kinematics
• How to measure the linear polarization of gluons in unpolarized proton using the heavy-quark pair production