The first search for ultra-rare K+decays into the π+e+e-e+e- final state is reported, using a dataset collected by the NA62 experiment at CERN in 2017–2018. An upper limit of 1.4×10^−8 at 90% CL is obtained for the branching ratio of the K+→π+e+e-e+e- decay, predicted in the Standard Model to be (7.2 ±0.7) ×10^−11. Upper limits at 90% CL are obtained at the level of 10^−9 for the branching ratios of two prompt decay chains involving pair-production of hidden-sector mediators: K+→π+ a a, a →e+e- and K+→π+S, S→A' A' , A' →e+e-.
Search for K+ decays into the π+e+e−e+e− final state
Arcidiacono, R.;Boretto, M.;Menichetti, E.;Migliore, E.;Soldi, D.;
2023-01-01
Abstract
The first search for ultra-rare K+decays into the π+e+e-e+e- final state is reported, using a dataset collected by the NA62 experiment at CERN in 2017–2018. An upper limit of 1.4×10^−8 at 90% CL is obtained for the branching ratio of the K+→π+e+e-e+e- decay, predicted in the Standard Model to be (7.2 ±0.7) ×10^−11. Upper limits at 90% CL are obtained at the level of 10^−9 for the branching ratios of two prompt decay chains involving pair-production of hidden-sector mediators: K+→π+ a a, a →e+e- and K+→π+S, S→A' A' , A' →e+e-.File in questo prodotto:
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