Parton distribution function dependence of benchmark Standard Model total cross sections at the 7 TeV LHC

TL;DR

This paper compares theoretical predictions of key Standard Model processes at the 7 TeV LHC using various parton distribution functions, focusing on the impact of different alpha_S values and luminosity functions.

Contribution

It provides a detailed comparison of cross section predictions from different PDFs and discusses the influence of alpha_S and luminosity functions on these predictions.

Findings

Significant variation in cross section predictions depending on PDF choice.

The strong coupling alpha_S notably affects the predicted cross sections.

Comparison with LHC data offers insights into PDF accuracy and consistency.

Abstract

We compare predictions for the W, Z, gg->H and t-tbar total cross sections at the Large Hadron Collider (LHC), for a centre-of-mass energy of 7 TeV, using the most recent publicly available next-to-leading order and next-to-next-to-leading order parton distribution functions (PDFs) from all PDF fitting groups. In particular, we focus on the dependence on the different values of the strong coupling, alpha_S(M_Z^2), used by each group. We also perform a comparison of the relevant quark-antiquark and gluon-gluon luminosity functions. We make some comments on the recent PDF4LHC recommendations. Finally, we discuss the comparison of data and theory for W and Z cross sections at the LHC.