### Elastic $Z^{0}$ production at HERA.

Takuya Nobe
Elastic $Z^{0}$ events $ep\rightarrow eZ^{0}p^{\left(*\right)}$ have been measured in $ep$ collisions at HERA using the ZEUS detector. The analysis is based on the data collected between 1996 and 2007, amounting to 496 pb$^{-1}$ of integrated luminosity. The $Z^{0}$ was measured in hadronic decay mode with elastic condition defined by $\eta_{max} < 3.0$, where $\eta_{max}$ is defined as the pseudorapidity of the energy deposit in the calorimeter closest to the proton beam direction. An excess of...