Di-jet event rates in deep-inelastic scattering at HERA

Abstract.

Di-jet event rates have been measured for deep-inelastic scattering in the kinematic domain $5 \lesssim Q^2 \lesssim 100$ GeV$^2$ and $10^{-4} \lesssim x_{Bj} \lesssim 10^{-2}$, and for jet transverse momenta squared $p_t^{*2}\gtrsim Q^2$. The analysis is based on data collected with the H1 detector at HERA in 1994 corresponding to an integrated luminosity of about 2 pb$^{-1}$. Jets are defined using a cone algorithm in the photon-proton centre of mass system requiring jet transverse momenta of at least 5 GeV. The di-jet event rates are shown as a function of $Q^2$ and $x_{Bj}$. Leading order models of point-like interacting photons fail to describe the data. Models which add resolved interacting photons or which implement the colour dipole model give a good description of the di-jet event rate. This is also the case for next-to-leading order calculations including contributions from direct and resolved photons.