Measurement of high-Q e-p neutral current cross sections at HERA and the extraction of xF3

Cross sections for e^-p neutral current deep inelastic scattering have been measured at a centre-of-mass energy of 318 GeV using an integrated luminosity of 15.9 pb^-1 collected with the ZEUS detector at HERA. Results on the double-differential cross-section in the range 185 < Q ² < 50 000 GeV² and 0.0037 < x < 0.75, as well as the single-differential cross-sections , and for Q ² > 200 GeV², are presented. To study the effect of Z-boson exchange, has also been measured for Q ² > 10 000 GeV². The structure function xF₃ has been extracted by combining the e^-p results presented here with the recent ZEUS measurements of e⁺p neutral current deep inelastic scattering. All results agree well with the predictions of the Standard Model. Received: 2 August 2002 / Revised version: 30 January 2003 / Published online: 24 March 2003