This Letter reports a measurement of the muon charge asymmetry from W bosons produced in proton-proton collisions at a centre-of-mass energy of 7 TeV with the ATLAS experiment at the LHC. The asymmetry is measured in the W -> mu nu decay mode as a function of the muon pseudorapidity using a data sample corresponding to a total integrated luminosity of 31 pb(-1). The results are compared to predictions based on next-to-leading order calculations with various parton distribution functions. This measurement provides information on the u and d quark momentum fractions in the proton. (C) 2011 CERN. Published by Elsevier B.V. All rights reserved. RI Jakubek, Jan/E-6530-2011; valente, paolo/A-6640-2010; Smirnov, Sergei/F-1014-2011; Fazio, Salvatore /G-5156-2010; Marti-Garcia, Salvador/F-3085-2011; Doyle, Anthony/C-5889-2009; Laycock, Paul/F-7543-2011; Conde Muino, Patricia/F-7696-2011; Stoicea, Gabriel/B-6717-2011; Robson, Aidan/G-1087-2011; Kladiva, Eduard/G-6305-2011; Losada, Marta/B-2261-2010; Jones, Roger/H-5578-2011; Gutierrez, Phillip/C-1161-2011; collins-tooth, christopher/A-9201-2012; Ferrando, James/A-9192-2012; Perrino, Roberto/B-4633-2010; De Cecco, Sandro/B-1016-2012; branchini, paolo/A-4857-2011; Wolter, Marcin/A-7412-2012; McKee, Shawn/B-6435-2012; Rotaru, Marina/A-3097-2011; O'Shea, Val/G-1279-2010; Nemecek, Stanislav/C-3487-2012; Buttar, Craig/D-3706-2011; Takai, Helio/C-3301-2012; Britton, David/F-2602-2010; Pina, Joao /C-4391-2012; Li, Xuefei/C-3861-2012; Smirnova, Lidia/D-8089-2012; Gladilin, Leonid/B-5226-2011; Kramarenko, Victor/E-1781-2012; Prokoshin, Fedor/E-2795-2012; Alexa, Calin/F-6345-2010; Pacheco Pages, Andres/C-5353-2011; Livan, Michele/D-7531-2012; Petrucci, Fabrizio/G-8348-2012; Wemans, Andre/A-6738-2012; Fabbri, Laura/H-3442-2012; Kurashige, Hisaya/H-4916-2012; Villa, Mauro/C-9883-2009; Delmastro, Marco/I-5599-2012

Measurement of the W charge asymmetry in the W -> mu nu decay mode in pp collisions at root s=7 TeV with the ATLAS detector