Nuclear transverse momentum imbalance in the color dipole approach at the LHC regime

Abstract

Transverse momentum broadening of a parton propagating through a large nucleus is evaluated in the color dipole approach using different models for the dipole cross section or unintegrated gluon distribution, which lead to different values of the coefficient $C_{\mathcal{F}}(0,s)$. Numerical calculations are compared to data extracted from LHCb and ALICE experiments for nuclear broadening of $J/\psi$. We find that different models which describe the small-$x$ data predict values of $\Delta p_T^2$ that agree reasonably well with experiment, specially for forward rapidity. The centrality dependence was also analysed and the models are consistent with the ALICE measurements.