Search for a $\tau^+ \tau^{\mathstrut -}$ resonance in $e^+ e^{\mathstrut -} \to \mu^+ \mu^{\mathstrut -} \tau^+ \tau^{\mathstrut -}$ events with the Belle II experiment

Sumitted to PubDB: 2022-06-25

Category: Physics / performance paper

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Principal Authors Luigi Corona, Giacomo De Pietro, Enrico Graziani
Date 2023-09-21
Working group Dark Sector and Low Multiplicity
Belle II Number BELLE2-PUB-PH-2022-004
Abstract We report the first search for a non-standard-model resonance decaying into $\tau$ pairs in $e^{+}e^{-}\rightarrow \mu^{+}\mu^{-} \tau^+\tau^-$ events in the 3.6-10 GeV/$c^{2}$ mass range. We use a 62.8 fb$^{-1}$ sample of $e^+e^-$ collisions collected at a center-of-mass energy of 10.58 GeV by the Belle II experiment at the SuperKEKB collider. The analysis probes three different models predicting a spin-1 particle coupling only to the heavier lepton families, a Higgs-like spin-0 particle that couples preferentially to charged leptons (leptophilic scalar), and an axion-like particle, respectively. We observe no evidence for a signal and set exclusion limits at 90% confidence level on the product of cross section and branching fraction into $\tau$ pairs, ranging from 0.7 fb to 24 fb, and on the couplings of these processes. We obtain world-leading constraints on the couplings for the leptophilic scalar model for masses above 6.5 GeV/$c^2$ and for the axion-like particle model over the entire mass range.
ArXiv https://arxiv.org/abs/2306.12294
Inspire https://inspirehep.net/literature/2670471
DOI 10.1103/PhysRevLett.131.121802
Reference Phys.Rev.Lett. 131, 121802 (2023)
Bibtex 
@article{Belle-II:2023ydz,
    author = "Adachi, I. and others",
    collaboration = "Belle-II",
    title = "{Search for a $\tau^+\tau^-$ resonance in $e^{+}e^{-}\rightarrow \mu^{+}\mu^{-} \tau^+\tau^-$ events with the Belle II experiment}",
    eprint = "2306.12294",
    archivePrefix = "arXiv",
    primaryClass = "hep-ex",
    reportNumber = "KEK preprint: 2022-32, Belle II preprint: 2022-006",
    doi = "10.1103/PhysRevLett.131.121802",
    journal = "Phys. Rev. Lett.",
    volume = "131",
    number = "12",
    pages = "121802",
    year = "2023"
}
Journal Phys.Rev.Lett.

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