Radiative order αs corrections on the hard photon production at HERA

In this thesis the QCD corrections to order αS to the production of hard photons at HERA, i.e. to the reaction e-p→e-γ(1+1) Jets, are calculated. The calculation of the virtual corrections is done by the application of standard methods. The real corrections are calculated by means of a new Lorentz-invariant method. The new method, which is implemented by computer algebraic means, is explained in detail. The differential cross section of the reaction e-p→e-γ(n+1) Jets up to order αs is studied numerically. using the angle of the outgoing photon as a tagging criterion the linear combination Σqi4fi(ξ) of the parton distributions fi(ξ) can be measured. (orig.)