Determination of PDFs and $\alpha_{S}(M_{Z})$ from Inclusive and Jet Measurements in DIS @ HERA

A simultaneous NLO QCD fit of the parton density functions (PDFs) of the proton and of the strong coupling $\alpha_{S}(M_{Z})$ is presented. The analysis is based on combined H1 and ZEUS inclusive DIS cross section measurements together with inclusive jet cross section measurements provided by both H1 and ZEUS collaborations. The inclusion of the jet data significantly reduces the correlation between the gluon PDF and the strong coupling, improving the precision of the gluon PDF and providing an accurate determination of $\alpha_{S}(M_{Z})$ using DIS data from HERA only.