Measurement of high-Q^{2} neutral current deep inelastic e^{+}p scattering cross sections with a longitudinally polarized positron beam at HERA

Measurements of neutral current cross sections for deep inelastic scattering in eþp collisions at HERA with a longitudinally polarized positron beam are presented. The single-differential cross-sections d=dQ2, d=dx and d=dy and the reduced cross section ~ are measured in the kinematic region Q2 > 185 GeV2 and y < 0:9, where Q2 is the four-momentum transfer squared, x the Bjorken scaling variable and y the inelasticity of the interaction. The measurements are performed separately for positively and negatively polarized positron beams. The measurements are based on an integrated luminosity of 135:5 pb1 collected with the ZEUS detector in 2006 and 2007 at a center-of-mass energy of 318 GeV. The structure functions F~ and FZ are determined by combining the eþp results presented in this paper 33 with previously published ep neutral current results. The asymmetry parameter Aþ is used to demonstrate the parity violation predicted in electroweak interactions. The measurements are well described by the predictions of the Standard Model