TY - JOUR
T1 - Search for K+ decays into the π+e+e−e+e− final state
AU - NA62 Collaboration
AU - Bache, Thomas
AU - Brunetti, Maria Brigida
AU - Duk, Viacheslav
AU - Fascianelli, Valeria
AU - Fry, John
AU - Gonnella, Francesco
AU - Goudzovski, Evgueni
AU - Henshaw, Jack
AU - Iacobuzio, Lorenza
AU - Kenworthy, Chandler
AU - Lurkin, Nicolas
AU - Newson, Francis
AU - Parkinson, Chris
AU - Romano, Angela
AU - Sanders, Jack
AU - Sergi, Antonino
AU - Sturgess, Andy
AU - Swallow, Joel
AU - Tomczak, Adam
PY - 2023/11/10
Y1 - 2023/11/10
N2 - 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+aa, a→e+e− and K+→π+S, S→A′A′, A′→e+e−.
AB - 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+aa, a→e+e− and K+→π+S, S→A′A′, A′→e+e−.
U2 - 10.1016/j.physletb.2023.138193
DO - 10.1016/j.physletb.2023.138193
M3 - Article
SN - 0370-2693
VL - 846
JO - Physics Letters B
JF - Physics Letters B
M1 - 138193
ER -