Göttingen 2012 – scientific programme

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T: Fachverband Teilchenphysik

T 26: QCD 2

T 26.1: Group Report

Tuesday, February 28, 2012, 16:45–17:05, ZHG 009

Measurement of D⁺⁻ production in DIS with the ZEUS Detector at HERA — Achim Geiser, Mykhailo Lisovyi, and •Oleksandr Zenaiev — DESY

The dominant contribution to charm production in deep inelastic scattering (DIS) at the HERA ep collider is boson-gluon fusion. Therefore the charm cross section is directly sensitive to the gluon density function in the proton as well as to the charm quark mass. A charm quark was identified by the reconstruction of the D⁺⁻ meson decay D⁺⁻ → K⁻⁺ π⁺⁻ π⁺⁻. Such weak decays allow to use the Micro-Vertex Detector (MVD) for lifetime tagging, to reduce combinatorial background and to increase the purity of the data sample. Inclusive and differential cross sections for D⁺⁻ production were measured and compared with previous results. The extraction of the charm contribution to the proton structure function F₂, F₂^c, and its inclusion into a general QCD fit allows to constrain the parton densities in the proton.