QCD Results from HERA

Abstract

New results on the measurements of the hadronic final state in neutral-current deep-inelastic scattering at HERA are presented. A combination of reduced charm and beauty cross sections is presented and the masses of the heavy quarks are determined to $m_c=1290\,(^{+78}_{-53})\,{\rm MeV}$ and $m_b=4049\,(^{+138}_{-118})\,{\rm MeV}$. The measurement of the production of prompt photons accompanied by a jet provides a precise test of QCD predictions. Measurements of jet production cross sections are presented and compared for the first time to next-to-next-to-leading order predictions (NNLO). The strong coupling constant is determined from inclusive jet and dijet production cross sections using NNLO predictions to $\alpha_s(m_Z)=0.1157\,(6)_{\rm exp}\,(^{+31}_{-26})_{\rm th}$.