New measurement of the K plus ? ? plus ? plus ?- decay at NA62

The flavour-changing neutral current decay K+ -> pi+mu+mu- is induced at the one-loop level in the Standard Model, and is well suited to explore its structure and, possibly, its extensions. The NA62 experiment took data in 2016-2018 with the main goal of measuring the K+ -> pi+ nu+ nu- decay. A scaled down di-muon trigger chain was operating along with the main trigger during the whole data taking period resulting in a large sample of about 3 x 1012 kaon decays in the fiducial volume recorded using the di-muon trigger. New results from an analysis of the K+ -> pi+ mu+ mu- decay using this sample will be presented.