Measurement of inelastic charmonium production at HERA

This thesis presents measurements of inelastic photoproduction and electroproduction of J/Ψ mesons in ep scattering at HERA. The data was collected by the H1 detector during the HERA II running and corresponds to an integrated luminosity of L ∼ 166 pb-1 in the photoproduction analysis and L ∼ 315 pb-1 in the electroproduction analysis. In both analyses the elasticity of the J/Ψ meson is restricted to a medium range of 0.3 ≤ z ≤ 0.9. The kinematic range of the photoproduction analysis is defined by Q2 ∼ 0 GeV2, 60 ≤Wγp≤ 240 GeV and PΤ,Ψ≥ 1 GeV2, whereas the electroproduction analysis is restricted to 3.6 ≤ Q2 ≤ 100 GeV2, 50 ≤Wγp≤ 225 GeV, and P*Τ,Ψ ≥ 1 GeV. Here P*Τ,Ψ denotes the transverse momentum of the J/Ψ in the γp center of mass frame. In both kinematic ranges, single differential and double differential cross sections are measured with increased precision with respect to previous analyses. The polarisation of the J/Ψ mesons is studied in fits to the decay angular distributions cos(Θ*) and φ*. The measured cross sections are compared to different theoretical predictions. The most successful calculation in describing the data accounts for higher order corrections by using a kΤ factorisation ansatz in the color singlet model (CSM). In addition, this thesis reviews the description of the data by calculations at leading and next to leading order in the CSM. The polarisation variables are compared to calculations in the factorisation ansatz in NRQCD, in addition to the leading order CSM predictions. (orig.)