Probing the proton structure with associated vector boson and heavy flavor jet production at the LHC

TL;DR

This paper compares two TMD-based approaches for modeling Z boson production with heavy flavor jets at the LHC, analyzing their sensitivity to gluon and quark distributions and comparing with experimental data.

Contribution

It introduces and compares two TMD-based Monte Carlo approaches for Z + heavy flavor jet production and assesses their agreement with LHC data and traditional pQCD calculations.

Findings

TMD-based predictions agree with LHC data at 8 and 13 TeV.

The approaches show sensitivity to gluon and quark distributions in the proton.

Predictions provide insights for searching intrinsic charm in the proton.

Abstract

We consider the production of $Z$ bosons associated with heavy (charm and beauty) jets at the LHC energies using two scenarios based on the transverse momentum dependent (TMD) parton densities in a proton. The first of them employs the Catani-Ciafaloni-Fiorani-Marchesini gluon evolution and is implemented in the Monte-Carlo event generator PEGASUS. Here, the heavy quarks are always produced in the hard partonic scattering. The second scheme is based on the parton branching approach, currently implemented into the Monte-Carlo event generator CASCADE. In this scenario, the $Z$ + jets sample is generated and then events containing the heavy flavor jet in a final state are selected. We compare the predictions obtained within these two TMD-based approaches to each other, investigate their sensitivity to the TMD gluon densities in a proton and estimate the effects coming from parton showers and double parton scattering mechanism. Additionally, we compare our predictions with the results of traditional (collinear) pQCD calculations performed at NLO accuracy. It is shown that the TMD-based results agree with the LHC experimental data collected at $\sqrt s = 8$ and $13$ TeV. We discuss the sensitivity of observables to the quark distributions in a proton and present predictions to search for the intrinsic charm signal in forthcoming analyses of the LHC experimental data.