${\nu }_{\mu }$ disappearance at the SPL, T2K-I and the Neutrino Factory

We study the ${\nu }_{\mu }$ disappearance channel at T2K-phase I and the SPL and analyse the achievable reduction of present uncertainties in ${\theta }_{23}$ and $\mathrm{\Delta }{m}_{23}^2$. We analyse the impact of discrete ambiguities in sign($\mathrm{\Delta }{m}^{2}23$) and sign($2\tan {\theta }_{23}$). We show how the disappearance channel at the Neutrino Factory is complementary to the golden'' and silver’’ appearance channels and can be used to reduce the eightfold-ambiguity problem in (${\theta }_{13}-\delta$).