Abstract
We investigate the sensitivity of electron-proton (ep) colliders for charged lepton flavor violation (cLFV) in an effective theory approach, considering a general effective Lagrangian for the conversion of an electron into a muon or a tau via the effective coupling to a neutral gauge boson or a neutral scalar field. For the photon, the Z boson and the Higgs particle of the Standard Model, we present the sensitivities of the LHeC for the coefficients of the effective operators, calculated from an analysis at the reconstructed level. As an example model where such flavor changing neutral current (FCNC) operators are generated at loop level, we consider the extension of the Standard Model by sterile neutrinos. We show that the LHeC could already probe the LFV conversion of an electron into a muon beyond the current experimental bounds, and could reach more than an order of magnitude higher sensitivity than the present limits for LFV conversion of an electron into a tau. We discuss that the high sensitivities are possible because the converted charged lepton is dominantly emitted in the backward direction, enabling an efficient separation of the signal from the background.
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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].
BaBar collaboration, Searches for Lepton Flavor Violation in the Decays τ ± → e± γ and τ ± → μ± γ, Phys. Rev. Lett. 104 (2010) 021802 [arXiv:0908.2381] [INSPIRE].
K. Hayasaka et al., Search for Lepton Flavor Violating Tau Decays into Three Leptons with 719 Million Produced τ + τ − Pairs, Phys. Lett. B 687 (2010) 139 [arXiv:1001.3221] [INSPIRE].
MEG II collaboration, The design of the MEG II experiment, Eur. Phys. J. C 78 (2018) 380 [arXiv:1801.04688] [INSPIRE].
Mu3e collaboration, Technical design of the phase I Mu3e experiment, arXiv:2009.11690 [INSPIRE].
S. Miscetti, Status of the Mu2e experiment at Fermilab, EPJ Web Conf. 234 (2020) 01010 [INSPIRE].
D. Shoukavy, COMET status and plans, EPJ Web Conf. 212 (2019) 01006 [INSPIRE].
A. Alekou et al., Accelerator system for the PRISM based muon to electron conversion experiment, in proceedings of the Community Summer Study 2013: Snowmass on the Mississippi (CSS2013), Minneapolis, MN, U.S.A., 29 July–6 August 2013, arXiv:1310.0804 [INSPIRE].
Belle-II collaboration, The Belle II Physics Book, Prog. Theor. Exp. Phys. 2019 (2019) 123C01 [Erratum ibid. 2020 (2020) 029201] [arXiv:1808.10567] [INSPIRE].
SuperB collaboration, SuperB: A High-Luminosity Asymmetric e+ e− Super Flavor Factory. Conceptual Design Report, arXiv:0709.0451 [INSPIRE].
A. Lusiani, Search for Lepton-Flavor-Violating Tau Decays at the B-factories, PoS HQL 2010 (2010) 054 [arXiv:1012.3733] [INSPIRE].
LHeC collaboration and FCC-he Study Group, The Large Hadron-Electron Collider at the HL-LHC, arXiv:2007.14491 [INSPIRE].
O. Bruening and M. Klein, The Large Hadron Electron Collider, Mod. Phys. Lett. A 28 (2013) 1330011 [arXiv:1305.2090] [INSPIRE].
LHeC Study Group, A Large Hadron Electron Collider at CERN: Report on the Physics and Design Concepts for Machine and Detector, J. Phys. G 39 (2012) 075001 [arXiv:1206.2913] [INSPIRE].
M. Klein, The Large Hadron Electron Collider Project, in proceedings of the 17th International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS 2009), Madrid, Spain, 26–30 April 2009, arXiv:0908.2877 [INSPIRE].
S. Antusch, A. Hammad and A. Rashed, Probing Z′ mediated charged lepton flavor violation with taus at the LHeC, Phys. Lett. B 810 (2020) 135796 [arXiv:2003.11091] [INSPIRE].
S. Jana, N. Okada and D. Raut, Displaced Vertex and Disappearing Track Signatures in type-III Seesaw, arXiv:1911.09037 [INSPIRE].
O. Flores-Sánchez, J. Hernández-Sánchez, C. G. Honorato, S. Moretti and S. Rosado, Light charged Higgs boson production at futures ep colliders, PoS DIS2019 (2019) 094 [arXiv:1908.09405] [INSPIRE].
G. Azuelos, M. D’Onofrio, S. Iwamoto and K. Wang, Search for the SUSY electroweak sector at ep colliders, Phys. Rev. D 101 (2020) 095015 [arXiv:1912.03823] [INSPIRE].
S. Antusch, O. Fischer and A. Hammad, Lepton-Trijet and Displaced Vertex Searches for Heavy Neutrinos at Future Electron-Proton Colliders, JHEP 03 (2020) 110 [arXiv:1908.02852] [INSPIRE].
L. Delle Rose, O. Fischer and A. Hammad, Prospects for Heavy Scalar Searches at the LHeC, Int. J. Mod. Phys. A 34 (2019) 1950127 [arXiv:1809.04321] [INSPIRE].
P. S. B. Dev, S. Khan, M. Mitra and S. K. Rai, Doubly-charged Higgs boson at a future electron-proton collider, Phys. Rev. D 99 (2019) 115015 [arXiv:1903.01431] [INSPIRE].
M. Klein and R. Yoshida, Collider Physics at HERA, Prog. Part. Nucl. Phys. 61 (2008) 343 [arXiv:0805.3334] [INSPIRE].
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].
T. Sjöstrand, S. Mrenna and P. Z. Skands, PYTHIA 6.4 Physics and Manual, JHEP 05 (2006) 026 [hep-ph/0603175] [INSPIRE].
DELPHES 3 collaboration, DELPHES 3, A modular framework for fast simulation of a generic collider experiment, JHEP 02 (2014) 057 [arXiv:1307.6346] [INSPIRE].
E. Conte, B. Fuks and G. Serret, MadAnalysis 5, A User-Friendly Framework for Collider Phenomenology, Comput. Phys. Commun. 184 (2013) 222 [arXiv:1206.1599] [INSPIRE].
S. Antusch and O. Fischer, Testing sterile neutrino extensions of the Standard Model at future lepton colliders, JHEP 05 (2015) 053 [arXiv:1502.05915] [INSPIRE].
S. Antusch, E. Cazzato and O. Fischer, Sterile neutrino searches at future e− e+, pp, and e− p colliders, Int. J. Mod. Phys. A 32 (2017) 1750078 [arXiv:1612.02728] [INSPIRE].
SINDRUM collaboration, Search for the Decay μ+ → e+ e+ e−, Nucl. Phys. B 299 (1988) 1 [INSPIRE].
V. A. Baranov et al., Search for μ+ → e+ e+ e− decay, Sov. J. Nucl. Phys. 53 (1991) 802 [Yad. Fiz. 53 (1991) 1302] [JINR-P1-90-464] [INSPIRE].
SINDRUM II collaboration, Test of lepton flavor conservation in μ → e conversion on titanium, Phys. Lett. B 317 (1993) 631 [INSPIRE].
S. Antusch, E. Cazzato and O. Fischer, Resolvable heavy neutrino-antineutrino oscillations at colliders, Mod. Phys. Lett. A 34 (2019) 1950061 [arXiv:1709.03797] [INSPIRE].
A. V. Bednyakov and Ş. H. Tanyildizi, A Mathematica Package for Calculation of One-Loop Penguins in FCNC Processes, Int. J. Mod. Phys. C 26 (2014) 1550042 [arXiv:1311.5546] [INSPIRE].
J. Bernabeu, G. A. Gonzalez-Sprinberg and J. Vidal, Weak dipole moments at e+ e− colliders, in proceedings of the Ringberg Workshop on Perspectives for Electroweak Interactions in e+ e− Collisions, Ringberg, Germany, 5–8 February 1995, pp. 329–342 [hep-ph/9505223] [INSPIRE].
R. Budny, B. Kayser and J. Primack, Weak Electric and Magnetic Dipole Moment Effects in e+ e− → l+ l−, Phys. Rev. D 15 (1977) 1222 [INSPIRE].
A. Gutiérrez-Rodríguez, M. A. Hernández-Ruíz, C. P. Castañeda-Almanza, A. Espinoza-Garrido and A. Chubykalo, Limits on the electromagnetic and weak dipole moments of the tau-lepton in a 331 model, Nucl. Phys. B Proc. Suppl. 253–255 (2014) 202 [INSPIRE].
C. Degrande, C. Duhr, B. Fuks, D. Grellscheid, O. Mattelaer and T. Reiter, UFO — The Universal FeynRules Output, Comput. Phys. Commun. 183 (2012) 1201 [arXiv:1108.2040] [INSPIRE].
E. Conte, B. Dumont, B. Fuks and C. Wymant, Designing and recasting LHC analyses with MadAnalysis 5, Eur. Phys. J. C 74 (2014) 3103 [arXiv:1405.3982] [INSPIRE].
G. Bagliesi, Tau tagging at ATLAS and CMS, in proceedings of the 17th Symposium on Hadron Collider Physics 2006 (HCP 2006), Durham, NC, U.S.A., 22–26 May 2006, arXiv:0707.0928 [INSPIRE].
CMS collaboration, Tau jet reconstruction and tagging with CMS, Eur. Phys. J. C 46 (2006) 1 [INSPIRE].
S. Antusch, E. Cazzato, O. Fischer, A. Hammad and K. Wang, Lepton Flavor Violating Dilepton Dijet Signatures from Sterile Neutrinos at Proton Colliders, JHEP 10 (2018) 067 [arXiv:1805.11400] [INSPIRE].
LHC Dark Matter Working Group, LHC Dark Matter Working Group: Next-generation spin-0 dark matter models, Phys. Dark Univ. 27 (2020) 100351 [arXiv:1810.09420] [INSPIRE].
SINDRUM II collaboration, A Search for muon to electron conversion in muonic gold, Eur. Phys. J. C 47 (2006) 337 [INSPIRE].
R. Alonso, M. Dhen, M. B. Gavela and T. Hambye, Muon conversion to electron in nuclei in type-I seesaw models, JHEP 01 (2013) 118 [arXiv:1209.2679] [INSPIRE].
B. W. Lee and R. E. Shrock, Natural Suppression of Symmetry Violation in Gauge Theories: Muon- and Electron-Lepton-Number Nonconservation, Phys. Rev. D 16 (1977) 1444 [INSPIRE].
FCC collaboration, FCC Physics Opportunities: Future Circular Collider Conceptual Design Report Volume 1, Eur. Phys. J. C 79 (2019) 474 [INSPIRE].
S. Antusch and O. Fischer, Non-unitarity of the leptonic mixing matrix: Present bounds and future sensitivities, JHEP 10 (2014) 094 [arXiv:1407.6607] [INSPIRE].
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Antusch, S., Hammad, A. & Rashed, A. Searching for charged lepton flavor violation at ep colliders. J. High Energ. Phys. 2021, 230 (2021). https://doi.org/10.1007/JHEP03(2021)230
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DOI: https://doi.org/10.1007/JHEP03(2021)230