%0 Journal Article
%T An investigation of the very rare K+ -> pi+ nu nubar decay
%A NA62 Collaboration (Cortina Gil, E. et al
%A Husek, T.
%J Journal of High Energy Physics
%D 2020
%V 11
%N 11
%I Springer
%@ 1029-8479
%G English
%F NA62CollaborationCortinaGil+Husek2020
%O WOS:000593745600001
%O exported from refbase (https://references.ific.uv.es/refbase/show.php?record=4624), last updated on Tue, 15 Dec 2020 11:41:36 +0000
%X The NA62 experiment reports an investigation of the K+-> pi+nu nu <overbar></mml:mover> mode from a sample of K+ decays collected in 2017 at the CERN SPS. The experiment has achieved a single event sensitivity of (0.389 +/- 0.024) x 10(-10), corresponding to 2.2 events assuming the Standard Model branching ratio of (8.4 +/- 1.0) x 10(-11). Two signal candidates are observed with an expected background of 1.5 events. Combined with the result of a similar analysis conducted by NA62 on a smaller data set recorded in 2016, the collaboration now reports an upper limit of 1.78 x 10(-10) for the K+-> pi+nu nu <overbar></mml:mover> branching ratio at 90% CL. This, together with the corresponding 68% CL measurement of (0.48<mml:mo>-0.48<mml:mo>+0.72) x 10(-10), are currently the most precise results worldwide, and are able to constrain some New Physics models that predict large enhancements still allowed by previous measurements.
%K Fixed target experiments
%K Flavor physics
%K Flavour Changing Neutral Currents
%K Rare decay
%R 10.1007/JHEP11(2020)042
%U https://arxiv.org/abs/2007.08218
%U https://doi.org/10.1007/JHEP11(2020)042
%P 042-57pp