### Measurement of high-$Q^2$ $e^+p$ neutral current cross sections at HERA and determination of the structure function $x\tilde{F_3}$.

Friederike Januschek
The cross sections for neutral current deep inelastic scattering in $e^+p$ collisions with a longitudinally polarised positron beam were measured using the ZEUS detector at HERA. The single-differential cross-sections $d\sigma/dQ^{2}$, $d\sigma/dx$ and $d\sigma/dy$ and the double-differential cross sections in $Q^{2}$ and x are presented in the kinematic region $Q^2 > \unit{185}{\GeV}^2$ and $y < 0.9$ for both positively and negatively polarised positron beams and for each polarisation state separately. The measurements are based on an...