Measurement of neutral and charged current cross-sections in positron-proton collisions at large momentum transfer

Abstract.

The inclusive single and double differential cross-sections for neutral and charged current processes with four-momentum transfer squared $Q^2$ between 150 and 30 000 GeV$^2$ and with Bjorken x between 0.0032 and 0.65 are measured in $e^+ p$ collisions. The data were taken with the H1 detector at HERA between 1994 and 1997, and they correspond to an integrated luminosity of $35.6\,{\rm pb}^{-1}$. The $Q^2$ evolution of the parton densities of the proton is tested, yielding no significant deviation from the prediction of perturbative QCD. The proton structure function $F_2(x,Q^2)$ is determined. An extraction of the u and d quark distributions at high x is presented. At high $Q^2$ electroweak effects of the heavy bosons $Z^\circ$ and $W$ are observed and found to be consistent with Standard Model expectation.