Search for an invisible $Z'$ in final states with two muons and missing energy at Belle II

Sumitted to PubDB: 2022-06-23

Category: Physics / performance paper

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Principal Authors Marcello Campajola, Giacomo De Pietro, Paul Feichtinger, Enrico Graziani, Gianluca Inguglia, Petar Rados, Laura Zani
Date 2023-06-07
Working group Dark Sector and Low Multiplicity
Belle II Number BELLE2-PUB-PH-2022-008
Abstract The $L_{\mu}-L_{\tau}$ extension of the standard model predicts the existence of a lepton-flavor-universality-violating $Z^{\prime}$ boson that couples only to the heavier lepton families. We search for such a $Z^\prime$ through its invisible decay in the process $e^+ e^- \to \mu^+ \mu^- Z^{\prime}$. We use a sample of electron-positron collisions at a center-of-mass energy of 10.58GeV collected by the Belle II experiment in 2019-2020, corresponding to an integrated luminosity of 79.7fb$^{-1}$. We find no excess over the expected standard-model background. We set 90$\%$-confidence-level upper limits on the cross section for this process as well as on the coupling of the model, which ranges from $3 \times 10^{-3}$ at low $Z^{\prime}$ masses to 1 at $Z^{\prime}$ masses of 8$GeV/c^{2}$.
ArXiv https://arxiv.org/abs/2212.03066
Inspire https://inspirehep.net/literature/2611344
DOI 10.1103/PhysRevLett.130.231801
Reference Phys.Rev.Lett. 130, 231801 (2023)
Bibtex 
@article{Belle-II:2022yaw,
    author = "Adachi, I. and others",
    collaboration = "Belle-II",
    title = "{Search for an Invisible Z' in a Final State with Two Muons and Missing Energy at Belle II}",
    eprint = "2212.03066",
    archivePrefix = "arXiv",
    primaryClass = "hep-ex",
    reportNumber = "Belle II Preprint 2022-008, KEK Preprint 2022-40",
    doi = "10.1103/PhysRevLett.130.231801",
    journal = "Phys. Rev. Lett.",
    volume = "130",
    number = "23",
    pages = "231801",
    year = "2023"
}
Journal Phys.Rev.Lett.

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