Eur. Phys. J. C (2009) 63: 189-285
https://doi.org/10.1140/epjc/s10052-009-1072-5

Regular Article - Theoretical Physics

Parton distributions for the LHC

¹ Institute for Particle Physics Phenomenology, University of Durham, Durham, DH1 3LE, UK
² Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
³ Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK

^* e-mail: watt@hep.ucl.ac.uk

Received: 1 March 2009
Revised: 27 April 2009
Published online: 4 July 2009

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 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.