Recent results and prospects from NA48/2: $K^{\pm} \rightarrow \pi^{0} l^{\pm}\nu$ and $K^{\pm} \rightarrow \pi^{+} \pi^{-} e^{\pm}\nu, K^{\pm} \rightarrow \pi^{0}\pi^{0}e^{\pm} \nu$ decays

In 2003-2004 the NA48/2 Collaboration at CERN collected a large sample of $K^{\pm}$ decays. Using data taken with minimal trigger conditions, a sample of $2.5 \times 10^{6}K^{\pm} \rightarrow \pi^{0}\mu^{\pm}\nu$ and $4.0 \times 10^{6}K^{\pm} \rightarrow \pi^{0}e^{\pm}\nu$ events was recorded, and allows precise measurements of the decay form factors. This report describes the event selection and the fitting procedure, and gives a preliminary result for the form factors in various parameterizations. In addition, with the full data sample collected, more than one million $K^{\pm} \rightarrow \pi^{+}\pi^{-}e^{\pm}\nu$ and about 45000 $K^{\pm} \rightarrow \pi^{0}\pi^{0}e^{\pm}\nu$ decays has been analysed. An improved determination of the branching ratio and high precision form factor measurements for $K^{\pm} \rightarrow \pi^{+}\pi^{-}e^{\pm}\nu$, and a preliminary result for the branching ratio of $K^{\pm} \rightarrow \pi^{0}\pi^{0}e^{\pm}\nu$ are presented in this paper. Future prospects include the observation of several thousands decays in similar muonic modes that will be studied at the NA62 experiment.