MULTIPARTON INTERACTIONS IN PHOTOPRODUCTION AT HERA

The high energy photoproduction of jets is being observed at the ep co llider, HERA. It may be that the HERA centre-of-mass energy is suffici ently large that the production of more than one pair of jets per ep c ollision becomes possible, owing to the large number density of the pr obed gluons. We construct a Monte Carlo model of such multiparton inte ractions and study their effects on a wide range of physical observabl es. The conclusion is that multiple interactions could have very signi ficant effects upon the photoproduction final state and that this woul d for example make extractions of the gluon density in the photon rath er difficult. Total rates for the production of many (i.e. greater tha n or equal to 3) jets could provide direct evidence for the presence o f multiple interactions, although parton showering and hadronization s ignificantly affect low transverse energy jets.