High-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>Q</mml:mi><mml:mn>2</mml:mn></mml:msup></mml:math>neutral current cross sections in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:mi>p</mml:mi></mml:math>deep inelastic scattering at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>318</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi mathvariant="normal">G</mml:mi><mml:mi mathvariant="normal">e</mml:mi><mml:mi mathvariant="normal">V</mml:mi></mml:math>

Cross sections for e^+p neutral current deep inelastic scattering have been\nmeasured at a centre-of-mass energy of sqrt{s}=318 GeV with the ZEUS detector\nat HERA using an integrated luminosity of 63.2 pb^-1. The double-differential\ncross section, d^2sigma/dxdQ^2, is presented for 200 GeV^2 &lt; Q^2 &lt; 30000 GeV^2\nand for 0.005 &lt; x &lt; 0.65. The single-differential cross-sections dsigma/dQ^2,\ndsigma/dx and dsigma/dy are presented for Q^2 &gt; 200 GeV^2. The effect of\nZ-boson exchange is seen in dsigma/dx measured for Q^2 &gt; 10000 GeV^2. The data\npresented here were combined with ZEUS e^+p neutral current data taken at\nsqrt{s}=300 GeV and the structure function F_2^{em} was extracted. All results\nagree well with the predictions of the Standard Model.\n Comment: Two references corrected. To be published in Physical Review D