H1prelim-04-033

Measurements of Forward Jet Production at low x in DIS

Reference A. Knutsson, presented at DIS2004 and DIS2005 (update for NLO QCD), Spring 2004
Document Conference paper
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Contact Albert Knutsson
Abstract New parton dynamics, characterized by an initial state cascade which is non-ordered in parton virtuality, are expected to become important in the kinematic region of small Bjorken-x in ep scattering at HERA. Evidence for this feature of QCD is searched for by studying events with a forward jet produced close to the direction of the outgoing proton beam in the angular range 7 < theta_jet < 20 degrees. The cross section for inclusive forward jet production is presented as a function of x. The energy flow around the forward jet has been studied in different rapidity regions to investigate how the energy compensation is described by models and whether the forward jet profile changes with rapidity. With the present statistics it is possible to measure the triple differential cross section d^3 sigma / dx dQ^2 dptjet^2, which covers the phase space region dominated by direct photon interactions Q^2 >> ptjet^2, as well as the two scale `BFKL' region Q^2 \sim ptjet^2 and the `resolved virtual photon' region (Q^2 << ptjet^2. In addition, events are studied with a hard central di-jet system in addition to the forward jet and the cross section for such topologies is measured as a function of the rapidity separation between the forward jet and the two hard jets. The measurements are compared with the predictions of models generating initial state emissions which are ordered and non-ordered in virtuality.
Comments version of the conference paper for ICHEP2004  
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