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 e(+)p collisions at HERA with a longitudinally polarized positron beam are presented. The single-differential cross-sections d sigma=dQ(2), d sigma=dx and d sigma=dy and the reduced cross section (sigma) over tilde are measured in the kinematic region Q(2) >185 GeV2 and y<0.9, where Q(2) 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 pb(-1) collected with the ZEUS detector in 2006 and 2007 at a center-of-mass energy of 318 GeV. The structure functions <(F3)over tilde> and F-3(gamma Z) are determined by combining the e(+)p results presented in this paper with previously published e(-)p neutral current results. The asymmetry parameter A(+) is used to demonstrate the parity violation predicted in electroweak interactions. The measurements are well described by the predictions of the Standard Model.