Heavy-quark deep-inelastic scattering with a running mass

We study the production of heavy quarks in deep-inelastic scattering within perturbative QCD. As a new result, we employ for the first time the running mass definition in the MS¯ scheme for deep-inelastic charm and bottom production. We observe an improved stability of the perturbative expansion and a reduced theoretical uncertainty due to variations of the renormalization and factorization scales. As our best estimate we extract from a global fit to fixed-target and HERA collider data for the charm-quark an MS¯ mass of mc(mc)=1.01±0.09(exp)±0.03(th)GeV.