First Studies of Three-Jet Production in Deep-Inelastic Scattering

Three-jet production in deep-inelastic scattering is studied with the H1 detector at HERA over a large range of four-momentum transfers 5 < Q² < 5000 GeV² and invariant three-jet masses 25 < M_3jet < 140 GeV. For the first time differential distributions of the three-jet cross section and angular distributions of the jets are used to test the predictions of perturbative QCD in next-to-leading order in α_s.