First search for $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ using the decay-in-flight technique

NA62 collaboration

The NA62 experiment at the CERN SPS reports the first search for $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ using the decay-in-flight technique, based on a sample of $1.21\times 10^{11}$ $K^{+}$ de…