The first search for ultra-rare K+ decays into the pi(+)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 1.4x10(-8) at 90% CL is obtained for the branching ratio of the K+ -> pi(+) e(+)e(-)e(+)e(-) decay, predicted in the Standard Model to be (7.2 +/- 0.7) x10(-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+. pi(+) aa, a -> e(+)e(-) and K+ -> pi(+) S, S -> A' A', A' -> e(+) e(-). (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).
Search for K+ decays into the π+e+e−e+e− final state
Cortina Gil, E.;Dalpiaz, P.;Fiorini, M.;Mazzolari, A.;Neri, I.;Norton, A.;Petrucci, F.;Soldani, M.;Wahl, H.;Bandiera, L.;Cotta Ramusino, A.;Gianoli, A.;Romagnoni, M.;Sytov, A.;Iacopini, E.;Latino, G.;Parenti, A.;Georgiev, G.;Lanfranchi, G.;D'Errico, M.;Giordano, R.;Santoni, C.;Barbanera, M.;Cenci, P.;Pepe, M.;Di Lella, L.;D'Agostini, G.;Turisini, M.;Valente, P.;Vicini, P.;Menichetti, E.;Ruggiero, G.;
2023
Abstract
The first search for ultra-rare K+ decays into the pi(+)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 1.4x10(-8) at 90% CL is obtained for the branching ratio of the K+ -> pi(+) e(+)e(-)e(+)e(-) decay, predicted in the Standard Model to be (7.2 +/- 0.7) x10(-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+. pi(+) aa, a -> e(+)e(-) and K+ -> pi(+) S, S -> A' A', A' -> e(+) e(-). (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.