Cross sections for $e^{+}p$ neutral current deep inelastic scattering have been measured at a center-of-mass energy of $\sqrt{s}=318\mathrm{G}\mathrm{e}\mathrm{V}$ with the ZEUS detector at HERA using an integrated luminosity of $63.2{\mathrm{p}\mathrm{b}}^{-1}$. The double-differential cross section, $d^2\sigma /dxd{Q}^2$, is presented for $200{\mathrm{G}\mathrm{e}\mathrm{V}}^2<Q^2<30000{\mathrm{G}\mathrm{e}\mathrm{V}}^2$ and for $0.005<x<0.65$. The single-differential cross sections $d\sigma /d{Q}^2$, $d\sigma /dx$ and $d\sigma /dy$ are presented for $Q^2>200{\mathrm{G}\mathrm{e}\mathrm{V}}^2$. The effect of $Z$-boson-exchange is seen in $d\sigma /dx$ measured for $Q^2>10000{\mathrm{G}\mathrm{e}\mathrm{V}}^2$. The data presented here were combined with ZEUS $e^{+}p$ neutral current data taken at $\sqrt{s}=300\mathrm{G}\mathrm{e}\mathrm{V}$ and the structure function $F_2^{\mathrm{e}\mathrm{m}}$ was extracted. All results agree well with the predictions of the Standard Model.

• Received 22 January 2004

DOI:https://doi.org/10.1103/PhysRevD.70.052001