Measurement of neutral currente±pcross sections at high Bjorkenxwith the ZEUS detector

The neutral current ${e}^{\ifmmode\pm\else\textpm\fi{}}p$ cross section has been measured up to values of Bjorken $x\ensuremath{\cong}1$ with the ZEUS detector at HERA using an integrated luminosity of $187\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ of ${e}^{\ensuremath{-}}p$ and $142\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ of ${e}^{+}p$ collisions at $\sqrt{s}=318\text{ }\text{ }\mathrm{GeV}$. Differential cross sections in $x$ and ${Q}^{2}$, the exchanged boson virtuality, are presented for ${Q}^{2}\ensuremath{\ge}725\text{ }\text{ }{\mathrm{GeV}}^{2}$. 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.