$K^+ \to \pi^+ \nu \overline{\nu}$ - NA62 First Result

TL;DR

The NA62 experiment reports a preliminary measurement of the rare decay $K^+ o \pi^+ u ar{ u}$ using a novel technique, observing one candidate event and setting an upper limit consistent with the Standard Model.

Contribution

This work introduces a new 'kaon decay-in-flight' method and provides the first result from the full 2016 dataset for this decay mode.

Findings

Observed one candidate event.

Set an upper limit of $14 imes 10^{-10}$ at 95% C.L.

Results agree with Standard Model predictions.

Abstract

The CERN NA62 experiment uses a novel "kaon decay-in-flight" technique to observe $K^+ \to \pi^+ \nu \overline{\nu}$. The preliminary result based on the analysis of the full 2016 dataset will be presented. In agreement with the Standard Model prediction, one candidate was observed. Under the background hypothesis, an upper limit of $14 \times 10^{-10}$ at 95 % C.L. was placed on the branching ratio.