Recent NA48/2 and NA62 results

Abstract

The NA48/2 Collaboration at CERN has accumulated and analysed unprecedented statistics of rare kaon decays in the $K_{e4}$ modes: $K_{e4}(+-)$ ($K^{\pm }\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}{e}^{\pm }\hat{I}½$) and $K_{e4}(00)$ ($K^{\pm }\to \ddot{I}{€}^0\ddot{I}{€}^0{e}^{\pm }\hat{I}½$) with nearly one percent background contamination. It leads to the improved measurement of branching fractions and detailed form factor studies. New final results from the analysis of 381 $K^{\pm }\to \ddot{I}{€}^{\pm }{\hat{I}}^3{\hat{I}}^3$ rare decay candidates collected by the NA48/2 and NA62 experiments at CERN are presented. The results include a decay rate measurement and fits to Chiral Perturbation Theory (ChPT) description.

Prepared for the Proceedings of "Moriond QCD and High Energy Interactions. March 22-29 2014." conference