The ultra-rare decay K+→π+νν¯, with a very precisely predicted branching ratio of less than 10−10, is one of the best candidates to reveal indirect effects of new physics at the highest mass scales. The NA62 experiment at CERN SPS is designed to measure Br(K+→π+νν¯) with a decay-in-flight technique, novel for this channel. NA62 took data in 2016, 2017 and 2018. Statistics collected in 2016 and 2017 allows NA62 to reach the Standard Model sensitivity for the K+→π+νν¯ search. The analysis of the 2018 data led to the most precise measurement ever performed, with more than 3σ significance in terms of process observation. A statistical reinterpretation of the analysis gives also the possibility to set limits on Br(K+→π+X), where X is a scalar or pseudo-scalar particle. The context of the measurement will be presented, the details of the analysis will be described, the results and the prospects will be illustrated.
26 mai 2021
par Francesco Brizioli (University of Perugia and INFN) se déroulera lundi 7 juin 2021 à 14h00.