High Q**2 neutral current cross-sections in E+ P deep inelastic scattering at S**(1/2) = 318-GeV

Cross sections for e(+)p neutral current deep inelastic scattering have been measured at a center-of-mass energy of roots=318 GeV with the ZEUS detector at HERA using an integrated luminosity of 63.2 pb(-1). The double-differential cross section, d(2)sigma/dxdQ(2), is presented for 200 GeV2 lt Q(2) lt 30 000 GeV2 and for 0.005 lt x lt 0.65. The single- differential cross sections dsigma/dQ(2), dsigma/dx and dsigma/dy are presented for Q(2) gt 200 GeV2. The effect of Z- boson-exchange is seen in dsigma/dx measured for Q(2) gt 10 000 GeV2. The data presented here were combined with ZEUS e(+)p neutral current data taken at roots=300 GeV and the structure function F-2(em) was extracted. All results agree well with the predictions of the Standard Model.