Measurement of the charm structure function of the proton at HERA Original Research Article

D∗ meson production cross sections have been measured in deep inelastic ep scattering at HERA. Using an integrated luminosity of 37 pb−1, the ZEUS collaboration has used both the 3-prong D∗+ → (D0 → K−π+)π+ (+ c.c.) and the 5-prong D∗+ → (D0 → K−π+π−π+)π+ (+ c.c.) decay channels to extract differential D∗ cross sections and View the MathML source. These cross sections are compared to NLO QCD calculations. The gluon density of the proton has also been determined directly from D∗ events by H1 and is compared to that obtained from a QCD analysis of F2.