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Search for an invisibly decaying $Z^{\prime}$ boson at Belle II in $e^+ e^- \to \mu^+ \mu^- (e^{\pm} \mu^{\mp})$ plus missing energy final states
- Source :
- Phys. Rev. Lett. 124, 141801 (2020)
- Publication Year :
- 2019
-
Abstract
- Theories beyond the standard model often predict the existence of an additional neutral boson, the $Z^{\prime}$. 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 $Z^{\prime}$ in the process $e^+ e^- \to \mu^+ \mu^- Z^{\prime}$ and of a lepton-flavor-violating $Z^{\prime}$ in $e^+ e^- \to e^{\pm} \mu^{\mp} Z^{\prime}$. 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 $L_{\mu}-L_{\tau}$ theory, into upper limits on the $Z^{\prime}$ coupling constant at the level of $5 \times 10^{-2}$ -- $1$ $M_{Z^\prime}\leq 6$ GeV/$c^2$.<br />Comment: 9 pages, 5 figures + supplemental materials. Accepted for publication in Physical Review Letters
- Subjects :
- High Energy Physics - Experiment
Subjects
Details
- Database :
- arXiv
- Journal :
- Phys. Rev. Lett. 124, 141801 (2020)
- Publication Type :
- Report
- Accession number :
- edsarx.1912.11276
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1103/PhysRevLett.124.141801