LHAPDF6: parton density access in the LHC precision era Andy Buckley, James Ferrando, Stephen Lloyd, Karl Nordström, Ben Page, Martin Rüfenacht, Marek Schönherr and Graeme Watt Eur. Phys. J. C, 75 3 (2015) 132 Published online: 20 March 2015 DOI: 10.1140/epjc/s10052-015-3318-8