Theories beyond the standard model often predict the existence of an additional neutral boson, the Z'. Using data collected by the Belle II experiment during 2018 at the SuperKEKB collider, we perform the first searches for the invisible decay of a Z' in the process e(+)e(-) -> mu(+)mu(-) Z' and of a lepton-flavor-violating Z' in e(+) e(-) -> e(+/-)mu(-/+)Z'. We do not find any excess of events and set 90% credibility level upper limits on the cross sections of these processes. We translate the former, in the framework of an L, - L, theory, into upper limits on the Z' coupling constant at the level of 5 x 10(-2) - 1 for M-z' <= 6 GeV/c(2).
Adachi, I., Ahlburg, P., Aihara, H., Akopov, N., Aloisio, A., Anh Ky, N., et al. (2020). Search for an Invisibly Decaying Z′ Boson at Belle II in e+e− → μ+μ−(e±μ∓) Plus Missing Energy Final States. PHYSICAL REVIEW LETTERS, 124(14), 141801-1-141801-9 [10.1103/PhysRevLett.124.141801].
Search for an Invisibly Decaying Z′ Boson at Belle II in e+e− → μ+μ−(e±μ∓) Plus Missing Energy Final States
Bernieri, E.Membro del Collaboration Group
;Bussino, S.Membro del Collaboration Group
;De Pietro, G.
Writing – Original Draft Preparation
;Martini, A.Writing – Original Draft Preparation
;
2020-01-01
Abstract
Theories beyond the standard model often predict the existence of an additional neutral boson, the Z'. Using data collected by the Belle II experiment during 2018 at the SuperKEKB collider, we perform the first searches for the invisible decay of a Z' in the process e(+)e(-) -> mu(+)mu(-) Z' and of a lepton-flavor-violating Z' in e(+) e(-) -> e(+/-)mu(-/+)Z'. We do not find any excess of events and set 90% credibility level upper limits on the cross sections of these processes. We translate the former, in the framework of an L, - L, theory, into upper limits on the Z' coupling constant at the level of 5 x 10(-2) - 1 for M-z' <= 6 GeV/c(2).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
