2-JET AND HEAVY-FLAVOR PHOTOPRODUCTION AT HERA

In this paper we study the electron-proton photoproduction at the HERA collider. We examine the possibility of using the photoproduction pro cesses to measure the parton distribution inside the proton and the ph oton. Particular emphasis is placed on the gluon content of the photon , which has not yet been measured directly. First we investigate the t wo-jet photoproduction, using the most up-to-date parton distribution parametrizations. We show that these processes are dominated by the ev ents where the photon is resolved into its hadronic constituents, for p(T) < 35 GeV. However, the resolved events initiated by the gluon com ponent of the photon dominate only for p(T) < 10 GeV, at most. We then explore the special case of the heavy-flavour pair production. We fin d that it could be employed to measure the gluon content of the photon , down to x(gamma) = 0.01, provided the direct events, where the photo n couples directly to the partons within the proton, could be eliminat ed.