Abstract
We study the exotic muon decays with five charged tracks in the final state. First, we investigate the Standard Model rate for μ+ → 3e+ 2e− 2ν (\( \mathcal{B} \) = 4.0 × 10−10) and find that the Mu3e experiment should have tens to hundreds of signal events per 1015 μ+ decays, depending on the signal selection strategy. We then turn to a neutrinoless μ+ → 3e+ 2e− decay that may arise in new-physics models with lepton-flavor-violating effective operators involving a dark Higgs hd. Following its production in μ+ → e+hd decays, the dark Higgs can undergo a decay cascade to two e+e− pairs through two dark photons, hd → γdγd → 2(e+e−). We show that a μ+ → 3e+ 2e− search at the Mu3e experiment, with potential sensitivity to the branching ratio at the \( \mathcal{O} \)(10−12) level or below, can explore new regions of parameter space and new physics scales as high as Λ ∼ 1015 GeV.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
References
Mu3e collaboration, Technical design of the phase I Mu3e experiment, Nucl. Instrum. Meth. A 1014 (2021) 165679 [arXiv:2009.11690] [INSPIRE].
SINDRUM collaboration, Search for the Decay μ+ → e+e+e−, Nucl. Phys. B 299 (1988) 1 [INSPIRE].
MEG collaboration, Search for the lepton flavour violating decay μ+ → e+γ with the full dataset of the MEG experiment, Eur. Phys. J. C 76 (2016) 434 [arXiv:1605.05081] [INSPIRE].
MEG II collaboration, The design of the MEG II experiment, Eur. Phys. J. C 78 (2018) 380 [arXiv:1801.04688] [INSPIRE].
COMET collaboration, COMET Phase-I Technical Design Report, PTEP 2020 (2020) 033C01 [arXiv:1812.09018] [INSPIRE].
N. Teshima, Status of the DeeMe Experiment, an Experimental Search for μ-e Conversion at J-PARC MLF, PoS NuFact2019 (2020) 082 [arXiv:1911.07143] [INSPIRE].
Mu2e collaboration, Mu2e Technical Design Report, arXiv:1501.05241 [https://doi.org/10.2172/1172555] [INSPIRE].
M. Fael and C. Greub, Next-to-leading order prediction for the decay μ → e (e+e−) \( \nu \overline{\nu} \), JHEP 01 (2017) 084 [arXiv:1611.03726] [INSPIRE].
G.M. Pruna, A. Signer and Y. Ulrich, Fully differential NLO predictions for the rare muon decay, Phys. Lett. B 765 (2017) 280 [arXiv:1611.03617] [INSPIRE].
P. Banerjee, T. Engel, A. Signer and Y. Ulrich, QED at NNLO with McMule, SciPost Phys. 9 (2020) 027 [arXiv:2007.01654] [INSPIRE].
B. Echenard, R. Essig and Y.-M. Zhong, Projections for Dark Photon Searches at Mu3e, JHEP 01 (2015) 113 [arXiv:1411.1770] [INSPIRE].
A. Flores-Tlalpa, G. López Castro and P. Roig, Five-body leptonic decays of muon and tau leptons, JHEP 04 (2016) 185 [arXiv:1508.01822] [INSPIRE].
J. Heeck and W. Rodejohann, Lepton flavor violation with displaced vertices, Phys. Lett. B 776 (2018) 385 [arXiv:1710.02062] [INSPIRE].
A.-K. Perrevoort, Sensitivity Studies on New Physics in the Mu3e Experiment and Development of Firmware for the Front-End of the Mu3e Pixel Detector, Ph.D. thesis, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany (2018) [INSPIRE].
P. Banerjee et al., High-precision muon decay predictions for ALP searches, SciPost Phys. 15 (2023) 021 [arXiv:2211.01040] [INSPIRE].
E. Goudzovski et al., New physics searches at kaon and hyperon factories, Rept. Prog. Phys. 86 (2023) 016201 [arXiv:2201.07805] [INSPIRE].
C. Antel et al., Feebly Interacting Particles: FIPs 2022 workshop report, in the proceedings of the Workshop on Feebly-Interacting Particles, CERN, Switzerland, October 17–21 (2022) [arXiv:2305.01715] [INSPIRE].
B. Batell, M. Pospelov and A. Ritz, Probing a Secluded U(1) at B-factories, Phys. Rev. D 79 (2009) 115008 [arXiv:0903.0363] [INSPIRE].
B. Batell, M. Pospelov and A. Ritz, Multi-lepton Signatures of a Hidden Sector in Rare B Decays, Phys. Rev. D 83 (2011) 054005 [arXiv:0911.4938] [INSPIRE].
E. Weihs and J. Zurita, Dark Higgs Models at the 7 TeV LHC, JHEP 02 (2012) 041 [arXiv:1110.5909] [INSPIRE].
D. Curtin, R. Essig, S. Gori and J. Shelton, Illuminating Dark Photons with High-Energy Colliders, JHEP 02 (2015) 157 [arXiv:1412.0018] [INSPIRE].
N. Blinov, E. Izaguirre and B. Shuve, Rare Z Boson Decays to a Hidden Sector, Phys. Rev. D 97 (2018) 015009 [arXiv:1710.07635] [INSPIRE].
A. Smolkovič, M. Tammaro and J. Zupan, Anomaly free Froggatt-Nielsen models of flavor, JHEP 10 (2019) 188 [Erratum ibid. 02 (2022) 033] [arXiv:1907.10063] [INSPIRE].
M. Hostert and M. Pospelov, Novel multilepton signatures of dark sectors in light meson decays, Phys. Rev. D 105 (2022) 015017 [arXiv:2012.02142] [INSPIRE].
A.L. Foguel, G.M. Salla and R.Z. Funchal, (In)Visible signatures of the minimal dark abelian gauge sector, JHEP 12 (2022) 063 [arXiv:2209.03383] [INSPIRE].
T. Ferber, A. Grohsjean and F. Kahlhoefer, Dark Higgs Bosons at Colliders, arXiv:2305.16169 [INSPIRE].
BaBar collaboration, Search for Low-Mass Dark-Sector Higgs Bosons, Phys. Rev. Lett. 108 (2012) 211801 [arXiv:1202.1313] [INSPIRE].
KLOE-2 collaboration, Search for dark Higgsstrahlung in e+e− → μ+μ− and missing energy events with the KLOE experiment, Phys. Lett. B 747 (2015) 365 [arXiv:1501.06795] [INSPIRE].
Belle collaboration, Search for the dark photon in B0 → A′A′, A′ → e+e−, μ+μ−, and π+π− decays at Belle, JHEP 04 (2021) 191 [arXiv:2012.02538] [INSPIRE].
CMS collaboration, Search for long-lived particles decaying into muon pairs in proton-proton collisions at \( \sqrt{s} \) = 13 TeV collected with a dedicated high-rate data stream, JHEP 04 (2022) 062 [arXiv:2112.13769] [INSPIRE].
ATLAS collaboration, Search for Higgs bosons decaying into new spin-0 or spin-1 particles in four-lepton final states with the ATLAS detector with 139 fb−1 of pp collision data at \( \sqrt{s} \) = 13 TeV, JHEP 03 (2022) 041 [arXiv:2110.13673] [INSPIRE].
CMS collaboration, Search for low-mass dilepton resonances in Higgs boson decays to four-lepton final states in proton-proton collisions at \( \sqrt{s} \) = 13 TeV, Eur. Phys. J. C 82 (2022) 290 [arXiv:2111.01299] [INSPIRE].
T. Husek, Standard Model estimate of K+ → π+4e branching ratio, Phys. Rev. D 106 (2022) L071301 [arXiv:2207.02234] [INSPIRE].
NA62 collaboration, Physics with kaons at NA62 in the proceedings of the 21st Conference on Flavor Physics and CP Violation (FPCP 2023), Lyon France, May 29–June 2 (2023).
J. Alwall et al., The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations, JHEP 07 (2014) 079 [arXiv:1405.0301] [INSPIRE].
Particle Data Group collaboration, Review of Particle Physics, PTEP 2022 (2022) 083C01 [INSPIRE].
SINDRUM collaboration, Search for the Decay μ+ → e+e+e−, Nucl. Phys. B 260 (1985) 1 [INSPIRE].
S.N. Gninenko and N.V. Krasnikov, The Muon anomalous magnetic moment and a new light gauge boson, Phys. Lett. B 513 (2001) 119 [hep-ph/0102222] [INSPIRE].
C.-Y. Chen, H. Davoudiasl, W.J. Marciano and C. Zhang, Implications of a light “dark Higgs” solution to the gμ − 2 discrepancy, Phys. Rev. D 93 (2016) 035006 [arXiv:1511.04715] [INSPIRE].
B. Batell et al., Muon anomalous magnetic moment through the leptonic Higgs portal, Phys. Rev. D 95 (2017) 075003 [arXiv:1606.04943] [INSPIRE].
C.-Y. Chen, M. Pospelov and Y.-M. Zhong, Muon Beam Experiments to Probe the Dark Sector, Phys. Rev. D 95 (2017) 115005 [arXiv:1701.07437] [INSPIRE].
S.N. Gninenko and N.V. Krasnikov, Probing the muon gμ − 2 anomaly, Lμ − Lτ gauge boson and Dark Matter in dark photon experiments, Phys. Lett. B 783 (2018) 24 [arXiv:1801.10448] [INSPIRE].
Y. Kahn, G. Krnjaic, N. Tran and A. Whitbeck, M3: a new muon missing momentum experiment to probe (g − 2)μ and dark matter at Fermilab, JHEP 09 (2018) 153 [arXiv:1804.03144] [INSPIRE].
TWIST collaboration, Search for two body muon decay signals, Phys. Rev. D 91 (2015) 052020 [arXiv:1409.0638] [INSPIRE].
PIENU collaboration, Improved search for two body muon decay μ+ → e+XH, Phys. Rev. D 101 (2020) 052014 [arXiv:2002.09170] [INSPIRE].
MEG collaboration, Search for lepton flavour violating muon decay mediated by a new light particle in the MEG experiment, Eur. Phys. J. C 80 (2020) 858 [arXiv:2005.00339] [INSPIRE].
SINDRUM collaboration, Limits for Shortlived Neutral Particles Emitted μ+ or π+ Decay, Phys. Lett. B 175 (1986) 101 [INSPIRE].
B. Holdom, Two U(1)’s and Epsilon Charge Shifts, Phys. Lett. B 166 (1986) 196 [INSPIRE].
FASER collaboration, First Physics Results from the FASER Experiment, in the proceedings of the 57th Rencontres de Moriond on Electroweak Interactions and Unified Theories, La Thuile Italy, March 18–25 (2023) [arXiv:2305.08665] [INSPIRE].
A. Efrati, A. Falkowski and Y. Soreq, Electroweak constraints on flavorful effective theories, JHEP 07 (2015) 018 [arXiv:1503.07872] [INSPIRE].
R. Balkin et al., On the implications of positive W mass shift, JHEP 05 (2022) 133 [arXiv:2204.05992] [INSPIRE].
J.M. Poutissou et al., A New Limit on the Decay μ+ → e+γγ, Nucl. Phys. B 80 (1974) 221 [INSPIRE].
G. Azuelos et al., A New Upper Limit of the Decay μ → eγγ, Phys. Rev. Lett. 51 (1983) 164 [INSPIRE].
R.D. Bolton et al., Search for Rare Muon Decays with the Crystal Box Detector, Phys. Rev. D 38 (1988) 2077 [INSPIRE].
J.D. Bowman, T.P. Cheng, L.-F. Li and H.S. Matis, New Upper Limit for μ → eγγ, Phys. Rev. Lett. 41 (1978) 442 [INSPIRE].
C.M. York, C.O. Kim and W. Kernan, Search for the reaction μ+ + e− → γ + γ, Phys. Rev. Lett. 3 (1959) 288.
I. Galon and J. Zupan, Dark sectors and enhanced h → τμ transitions, JHEP 05 (2017) 083 [arXiv:1701.08767] [INSPIRE].
CMS collaboration, Search for the lepton-flavor violating decay of the Higgs boson and additional Higgs bosons in the eμ final state in proton-proton collisions at \( \sqrt{s} \) = 13 TeV, arXiv:2305.18106 [INSPIRE].
ATLAS collaboration, Search for the Higgs boson decays H → ee and H → eμ in pp collisions at \( \sqrt{s} \) = 13 TeV with the ATLAS detector, Phys. Lett. B 801 (2020) 135148 [arXiv:1909.10235] [INSPIRE].
ATLAS collaboration, A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery, Nature 607 (2022) 52 [Erratum ibid. 612 (2022) E24] [arXiv:2207.00092] [INSPIRE].
R. Harnik, J. Kopp and J. Zupan, Flavor Violating Higgs Decays, JHEP 03 (2013) 026 [arXiv:1209.1397] [INSPIRE].
A. Navarro and J. Eschle, phasespace: n-body phase space generation in Python, J. Open Source Softw. 4 (2019) 1570.
FASER collaboration, First Results from the Search for Dark Photons with the FASER Detector at the LHC, CERN-FASER-CONF-2023-001, CERN, Geneva (2023).
NA62 collaboration, Search for dark photon decays to μ+μ− at NA62, JHEP 09 (2023) 035 [arXiv:2303.08666] [INSPIRE].
P. Ilten, Y. Soreq, M. Williams and W. Xue, Serendipity in dark photon searches, JHEP 06 (2018) 004 [arXiv:1801.04847] [INSPIRE].
Acknowledgments
We thank Drs. B. Echenard, A.-K. Perrevoort, and F. Wauters for valuable discussions and correspondence. JZ and TM acknowledge support in part by the DOE grant de-sc0011784 and NSF OAC-2103889. MP is supported in part by the DOE grant DE-SC0011842. This research was supported in part by Perimeter Institute for Theoretical Physics. Research at Perimeter Institute is supported by the Government of Canada through the Department of Innovation, Science and Economic Development and by the Province of Ontario through the Ministry of Research, Innovation and Science.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
ArXiv ePrint: 2306.15631
Rights and permissions
Open Access . This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.
About this article
Cite this article
Hostert, M., Menzo, T., Pospelov, M. et al. New physics in multi-electron muon decays. J. High Energ. Phys. 2023, 6 (2023). https://doi.org/10.1007/JHEP10(2023)006
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/JHEP10(2023)006