Parton distribution functions and QCD coupling constant from LHC and non-LHC data

TL;DR

This paper performs a comprehensive QCD analysis of parton distribution functions using diverse experimental data, including LHC and non-LHC sources, to refine the understanding of gluon PDFs and the strong coupling constant, especially at large-x.

Contribution

It introduces a detailed NLO and NNLO QCD analysis incorporating various experimental datasets to improve the determination of PDFs and the strong coupling constant, with a focus on large-x gluon PDFs and intrinsic charm.

Findings

Large-x gluon PDF is significantly affected by LHC data.

The strong coupling constant $\alpha_s(M_Z^2)$ is refined using combined datasets.

Intrinsic charm at large-x is modeled with BHPS, informing future LHC experiments.

Abstract

We present a new QCD analysis of parton distribution functions (PDFs) at the next-to-leading order (NLO) and next-to-next-to-leading order (NNLO). In the present paper, the role of special types of experimental measurements for extracting PDFs is investigated and simultaneously the values of the strong coupling constant are determined. Essential elements of this QCD analysis are: the HERA combined data as a base, heavy quark cross section measurement together with Tevatron data on jet production and H1 and ZEUS jet cross sections as "non-LHC" data, and especially the "LHC" data set for top-quark and jet cross sections. These different data sets have allowed detailed information at low $x$, worth information on the nucleon's flavor and have played an important role for some PDFs at large-$x$ and strong coupling constant. Since the large-$x$ gluon PDF benefits from an accurate determination of quark PDFs, we have enough motivation to focus on the top-quark production and jet cross section measurements from LHC to find the impact of these data on the gluon PDF and strong coupling constant. These experimental data have an impact on the relative uncertainties of PDF. The gluon PDF at large-$x$ and the values of $\alpha_s(M_Z^2)$ are affected significantly. Although, the main motivation of this paper is to focus on gluon PDF and also its uncertainty at large-$x$, but notice to heavy PDFs behavior in this region is also very important. We study the intrinsic charm (IC) using BHPS model with together our extracted extrinsic charm PDF at large $x$ which can be very worth for future experiment at the LHC.