Measurement of dijet production at low Q 2 at HERA
Triple differential dijet cross sections in interactions are presented in the region of photon virtualities 2 < Q 2 < 80 GeV2, inelasticities 0.1 < y < 0.85, jet transverse energies E * T 1 > 7 GeV, E * T 2 > 5 GeV, and pseudorapidities . The measurements are made in the centre-of-mass frame, using an integrated luminosity of 57 pb-1. The data are compared with NLO QCD calculations and LO Monte Carlo programs with and without a resolved virtual photon contribution. NLO QCD calculations fail to describe the region of low Q 2 and low jet transverse energies, in contrast to a LO Monte Carlo generator which includes direct and resolved photon interactions with both transversely and longitudinally polarised photons. Initial and final state parton showers are tested as a mechanism for including higher order QCD effects in low E T jet production.
© Springer-Verlag, 2004