NNLO constraints on proton PDFs from the SeaQuest and STAR experiments and other developments in the CTEQ-TEA global analysis

TL;DR

This paper reviews recent advances in the global analysis of proton PDFs by the CTEQ-TEA group, including comparisons with experimental data and developments in specialized PDFs and nuclear effects.

Contribution

It introduces new PDF sets and compares various theoretical approaches with experimental data, enhancing the understanding of proton structure.

Findings

CT18 NNLO predictions align well with LHC 13 TeV data.

Specialized PDFs like CT18X and CT18sx incorporate saturation and small-x resummation effects.

Nuclear effects in deuteron influence parton distribution extractions.

Abstract

We review progress in the global QCD analysis by the CTEQ-TEA group since the publication of CT18 parton distribution functions (PDFs) in the proton. Specifically, we discuss comparisons of CT18 NNLO predictions with the LHC 13 TeV measurements as well as with the FNAL SeaQuest and BNL STAR data on lepton pair production. The specialized CT18X PDFs approximating saturation effects are compared with the CT18sx PDFs obtained using NLL/NLO small-$x$ resummation. Short summaries are presented for the special CT18 parton distributions with fitted charm and with lattice QCD inputs. A recent comparative analysis of the impact of deuteron nuclear effects on the parton distributions by the CTEQ-JLab and CTEQ-TEA groups is summarized.