Parton distribution functions and hard QCD at HERA

Abstract

The H1 and ZEUS collaborations at the electron-proton collider HERA have measured inclusive neutral and charged current deep inelastic scattering (DIS) cross sections over six orders of magnitude in negative four-momentum-transfer squared, Q 2 , and Bjorken x. All these measurements were combined to obtain one coherent inclusive HERA data set. This set was used as the sole input to the QCD analysis resulting in the HERAPDF2.0 set of parton distribution functions. An inclusion of HERA data on jet and charm production to the QCD fit allowed a simultaneous determination of parton distributions and the strong coupling. An extension of earlier measurements on multijet production in DIS at high Q 2 to low values of Q 2 and to low values of the jet transverse momentum at high Q 2 is presented here as well as. A combination of the final H1 and ZEUS inclusive D * ± -meson production cross sections in DIS as a function of Q 2 , inelasticity y and D * ± -meson variables, and a measurement of isolated photon production in DIS accompanied by jets using the ZEUS detector are also presented. All these results are compared to QCD calculations.