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

TL;DR

This paper investigates the transverse momentum broadening of particles in high-energy nuclear collisions using the color dipole approach, comparing models with experimental data from LHCb and ALICE to understand nuclear effects at the LHC.

Contribution

It evaluates different dipole models for transverse momentum broadening and compares their predictions with experimental data, providing insights into nuclear effects at small-x in high-energy collisions.

Findings

Models agree with experimental data for forward rapidity.

Different models predict similar broadening values at small-x.

Centrality dependence matches ALICE measurements.

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.