Parton distributions for the LHC

TL;DR

This paper provides updated parton distribution functions (PDFs) for the LHC, incorporating new experimental data and advanced uncertainty analysis, to improve theoretical predictions for collider physics.

Contribution

It introduces the MSTW 2008 PDFs, including higher-order calculations and a new uncertainty propagation method, replacing previous sets for accurate LHC data analysis.

Findings

Updated PDFs with next-to-next-to-leading order accuracy

Inclusion of new Tevatron and neutrino data sets

Predictions for W and Z cross sections at LHC and Tevatron

Abstract

We present updated leading-order, next-to-leading order and next-to-next-to-leading order parton distribution functions ("MSTW 2008") determined from global analysis of hard-scattering data within the standard framework of leading-twist fixed-order collinear factorisation in the MSbar scheme. These parton distributions supersede the previously available "MRST" sets and should be used for the first LHC data-taking and for the associated theoretical calculations. New data sets fitted include CCFR/NuTeV dimuon cross sections, which constrain the strange quark and antiquark distributions, and Tevatron Run II data on inclusive jet production, the lepton charge asymmetry from W decays and the Z rapidity distribution. Uncertainties are propagated from the experimental errors on the fitted data points using a new dynamic procedure for each eigenvector of the covariance matrix. We discuss the major changes compared to previous MRST fits, briefly compare to parton distributions obtained by other fitting groups, and give predictions for the W and Z total cross sections at the Tevatron and LHC.