Measurement of neutral current e$\pm$p cross sections at high Bjorken x with the ZEUS detector

The neutral current e±p cross section has been measured up to values of Bjorken x ≅ 1 with the ZEUS detector at HERA using an integrated luminosity of 187 pb−1 of e−p and 142 pb−1 of eþp collisions at ffiffi s p ¼ 318 GeV. Differential cross sections in x and Q2, the exchanged boson virtuality, are presented for Q2 ≥ 725 GeV2. An improved reconstruction method and greatly increased amount of data allows a finer binning in the high-x region of the neutral current cross section and leads to a measurement with much improved precision compared to a similar earlier analysis. The measurements are compared to Standard Model expectations based on a variety of recent parton distribution functions.