MRST2001: partons and $\alpha_S$ from precise deep inelastic scattering and Tevatron jet data

Abstract.

We use all the available new precise data for deep inelastic and related hard scattering processes to perform NLO global parton analyses. These new data allow an improved determination of partons and, in particular, the inclusion of the recent measurements of the structure functions at HERA and of the inclusive jets at the Tevatron help to determine the gluon distribution and $\alpha_S$ better than ever before. We find a somewhat smaller gluon at low x than previous determinations and that $\alpha_S (M_Z^2) = 0.119 \pm 0.002 (\rm expt.) \pm 0.003 (\rm theory)$.