Recent results in kaon physics

A review of the present experimental status of the K → πνν (Kπνν) and other kaon decay analyses at experiments NA62 (CERN) and KOTO (J-PARC) is given. The Kπνν decay is one of the best candidates among the rare meson decays for indirect searches for new physics in the mass ranges complementary to those accessible by current accelerators. The Standard Model (SM) prediction of the branching fraction (B) of the Kπνν decay is lower than 10−10 in both neutral and charged modes. The NA62 experiment aims to measure the B of the charged mode with better than 10% precision. Three candidate events, compatible with the SM prediction, have been observed from a sample of 2.12×1012 K+ decays collected in 2016 and 2017 by NA62. More than twice the statistics is available in the 2018 dataset currently being analysed. The KOTO experiment in Japan aims to measure B(KL → π0νν) using a technique similar to NA62, but with much lower momentum. In the first dataset taken in 2015 zero signal candidate events were observed. The current status of the analysis of the 2016-2018 dataset with 1.4 times more data is presented. Finally, the most recent results of other physics analyses at the NA62 experiment are summarised

Recent results in kaon physics

A review of the present experimental status of the K → πνν (Kπνν) and other kaon decay analyses at experiments NA62 (CERN) and KOTO (J-PARC) is given. The Kπνν decay is one of the best candidates among the rare meson decays for indirect searches for new physics in the mass ranges complementary to those accessible by current accelerators. The Standard Model (SM) prediction of the branching fraction (B) of the Kπνν decay is lower than 10−10 in both neutral and charged modes. The NA62 experiment aims to measure the B of the charged mode with better than 10% precision. Three candidate events, compatible with the SM prediction, have been observed from a sample of 2.12×1012 K+ decays collected in 2016 and 2017 by NA62. More than twice the statistics is available in the 2018 dataset currently being analysed. The KOTO experiment in Japan aims to measure B(KL → π0νν) using a technique similar to NA62, but with much lower momentum. In the first dataset taken in 2015 zero signal candidate events were observed. The current status of the analysis of the 2016-2018 dataset with 1.4 times more data is presented. Finally, the most recent results of other physics analyses at the NA62 experiment are summarised

Search for an invisible vector boson from π0 decays at NA62

2-s2.0-85098916005The search for an invisible vector boson from π0 decays at the NA62 experiment at CERN Super Proton Syncrotron (SPS) is discussed. Within the proposed models for physics beyond the SM, hidden sectors consisting of new, light, weakly-coupled particles are a particularly compelling possibility. Thanks to the high beam intensity, the extremely good performance of the photon detection systems, particle identification system and the detectors timing, NA62 is suited to search for these new particles. Here the search for a dark photon from π0 decays using the K+ → π+π0, π0 → A0γ decay chain is illustrated. The result from the analysis of a sub-sample of 2016 data is reported, corresponding to 1% of the full statistics collected in 2016-2018. A new upper limit on the π0 → A0γ branching ratio has been set as a function of the dark photon mass, thus producing a new upper limit on the dark photon coupling parameter [1]

Latest results from the NA62 experiment at CERN

NA62 is a fixed target kaon experiment at the CERN SPS which aims at measuring the branching ratio of the $K^+\to\pi^+\nu\bar{\nu}$ decay with 10% precision. This ultra-rare kaon decay is theoretically extremely clean and an ideal place to look for physics beyond the Standard Model. The NA62 experiment has been running in 2016-2018 and has accumulated a large amount of kaon decays. The final result of the $K^+\to\pi^+\nu\bar{\nu}$ analysis using the 2016 dataset is discussed as well as prospects for the analysis of the 2017 dataset. NA62 also has sensitivity to various other rare and forbidden kaon decays, as well as some hidden sector models. The results of a search for the Lepton Number Violating decays $K^+\to\pi^-\ell^+\ell^+\ [\ell=e,\mu]$ is presented, along with new limits on the existence of a dark photon