and, in addition, $M_W$ as a free parameter. The CC cross sections depend directly on $M_W$ as shown in Eqs. \[eqn:xsec\_CC1\] and \[eqn:xsec\_CC2\]. However, with $G_F$ rewritten as in Eq. \[eqn:GF\], the NC data also contribute to the fit. The value extracted for $M_W$ is

$$\nonumber 
  M_W = 80.68~ \pm 0.28 \,{\rm {\scriptstyle{(experimental/fit)}}}~ 
          ^{+0.12}_{-0.01} \,{\rm {\scriptstyle{(model)}}} 
        ~ ^{+0.23}_{-0.01} \,{\rm {\scriptstyle{(parameterisation)}}}\,{\rm GeV}~.$$

This $t$-channel determination is in agreement with the PDG14 value of $80.385\pm0.015$GeV, which is dominated by $s$-channel processes. The result presented here is a substantial improvement compared to a result published by H1 using HERAI data [@ZH1].

Finally, a fit ZEUS-EW-S-W was performed with 13 free PDF parameters and both $\sin^2\theta_W$ and $M_W$ as free parameters and with $G_F$ rewritten as described in Eq. \[eqn:GF\]. The resulting values are $$\begin{aligned}
\nonumber
  \sin^2\theta_W &=& 0.2293~ \pm 0.0031 \,{\rm {\scriptstyle{(experimental/fit)}}}~ 
                             ^{+0.0005}_{-0.0001} \,{\rm {\scriptstyle{(model)}}} 
                           ~ ^{+0.0003}_{-0.0001} \,{\rm {\scriptstyle{(parameterisation)}}}~, \\ 
\nonumber
   ~~  \\
\nonumber
  M_W &=& 79.30~ \pm 0.76 \,{\rm {\scriptstyle{(experimental/fit)}}}~ 
            ^{+0.38}_{-0.08} \,{\rm {\scriptstyle{(model)}}} 
          ~ ^{+0.48}_{-0.10} \,{\rm {\scriptstyle{(parameterisation)}}}\,{\rm GeV}~.  \end{aligned}$$ The uncertainties on $\sin^2\theta_W$ and $M_W$ are substantially larger than for the determination through ZEUS-EW-S and ZEUS-EW-W. The values are compatible within these uncertainties. The correlation between the EW parameters and the PDF 