2026/07/17 by NA62 Collaboration
#hep-ex
The NA62 experiment has measured the branching ratio of the rare decay K+→π+νν using data collected in 2023 and 2024 at the CERN SPS, obtaining \rm B\rm 2023-2024(K+→π+νν) = (7.2+2.3-2.1)×10-11. With results from data collected between 2016 and 2022, the analysis gives \rm B\rm 2016-2024(K+→π+νν) = (9.6+1.9-1.8)×10-11, corresponding to a relative precision of 20%. This value is consistent with Standard Model predictions.