TMD parton densities and corresponding parton showers: the advantage of four- and five-flavour schemes

TL;DR

This paper compares four- and five-flavour schemes for calculating Z + b-jet production, demonstrating the effectiveness of TMD parton distributions and showers in matching LHC data.

Contribution

First set of collinear and TMD parton distributions in the four-flavour scheme using the Parton-Branching approach, enabling detailed heavy flavor studies.

Findings

Good agreement with CMS and ATLAS measurements at 8 and 13 TeV

Demonstrated the reliability of PB-TMD distributions and showers

Provided insights into heavy flavor parton dynamics

Abstract

The calculations of $Z + b{\bar b}$ tagged jet production performed in the four- and five-flavour schemes allow for detailed comparison of the heavy flavour structure of collinear and transverse momentum dependent (TMD) parton distributions as well as for detailed investigations of heavy quarks radiated during the initial state parton shower cascade. We have determined the first set of collinear and TMD parton distributions in the four-flavour scheme with NLO DGLAP splitting functions within the Parton-Branching (PB) approach. The four- and five-flavour PB-TMD distributions were used to calculate $Z + b{\bar b}$ tagged jet production at LHC energies and very good agreement with measurements obtained at $\sqrt{s} = 8, 13 $ TeV by the CMS and ATLAS collaborations is observed. The different configurations of the hard process in the four- and five-flavour schemes allow for a detailed investigation of the performance of heavy flavor collinear and TMD parton distributions and the corresponding initial TMD parton shower, giving confidence in the evolution of the PB-TMD parton densities as well as in the PB-TMD parton shower.