Abstract
Run-I results from the CMS collaboration show an excess of events in the decay h → μτ e with a local significances of 2.4σ. This could be the first hint of flavour violation in the Higgs sector. We summarise the bounds on the flavour violating Yukawa couplings from direct searches, low energy measurements and projected future experiments. We discuss the sensitivity of upcoming HL-LHC runs and future lepton colliders in measuring lepton-flavour violating couplings using an effective field theory framework. For the HL-LHC we find limits on BR(h → μτ ) and BR(h → eτ ) ≲ \( \mathcal{O}(0.5)\% \) and on BR(h → eμ) ≲ \( \mathcal{O}(0.02)\% \). For an ILC with center-of-mass energy of 1 TeV we expect BR(h → eτ) and BR(h → μτ ) to be measurable down to \( \mathcal{O}(0.2)\% \).
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
ATLAS collaboration, Observation of a new particle in the search for the standard model Higgs boson with the ATLAS detector at the LHC, Phys. Lett. B 716 (2012) 1 [arXiv:1207.7214] [INSPIRE].
CMS collaboration, Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC, Phys. Lett. B 716 (2012) 30 [arXiv:1207.7235] [INSPIRE].
ATLAS and CMS collaborations, Measurements of the Higgs boson production and decay rates and constraints on its couplings from a combined ATLAS and CMS analysis of the LHC pp collision data at \( \sqrt{s}=7 \) and 8 TeV, ATLAS-CONF-2015-044 (2015).
ATLAS collaboration, Measurements of the Higgs boson production and decay rates and coupling strengths using pp collision data at \( \sqrt{s}=7 \) and 8 TeV in the ATLAS experiment, Eur. Phys. J. C 76 (2016) 6 [arXiv:1507.04548] [INSPIRE].
CMS collaboration, Precise determination of the mass of the Higgs boson and tests of compatibility of its couplings with the standard model predictions using proton collisions at 7 and 8 TeV, Eur. Phys. J. C 75 (2015) 212 [arXiv:1412.8662] [INSPIRE].
ATLAS collaboration, Evidence for the Higgs-boson Yukawa coupling to tau leptons with the ATLAS detector, JHEP 04 (2015) 117 [arXiv:1501.04943] [INSPIRE].
CMS collaboration, Evidence for the 125 GeV Higgs boson decaying to a pair of τ leptons, JHEP 05 (2014) 104 [arXiv:1401.5041] [INSPIRE].
CMS collaboration, Search for the associated production of the Higgs boson with a top-quark pair, JHEP 09 (2014) 087 [Erratum ibid. 10 (2014) 106] [arXiv:1408.1682] [INSPIRE].
https://twiki.cern.ch/twiki/bin/view/CMSPublic/ttHCombinationTWiki.
ATLAS collaboration, Search for H → γγ produced in association with top quarks and constraints on the Yukawa coupling between the top quark and the Higgs boson using data taken at 7 TeV and 8 TeV with the ATLAS detector, Phys. Lett. B 740 (2015) 222 [arXiv:1409.3122] [INSPIRE].
ATLAS collaboration, Search for the associated production of the Higgs boson with a top quark pair in multilepton final states with the ATLAS detector, Phys. Lett. B 749 (2015) 519 [arXiv:1506.05988] [INSPIRE].
ATLAS collaboration, Search for the Standard Model Higgs boson produced in association with top quarks and decaying into \( b\overline{b} \) in pp collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector, Eur. Phys. J. C 75 (2015) 349 [arXiv:1503.05066] [INSPIRE].
ATLAS collaboration, Search for the standard model Higgs boson decay to μ + μ − with the ATLAS detector, Phys. Lett. B 738 (2014) 68 [arXiv:1406.7663] [INSPIRE].
CMS collaboration, Search for a standard model-like Higgs boson in the μ + μ − and e + e − decay channels at the LHC, Phys. Lett. B 744 (2015) 184 [arXiv:1410.6679] [INSPIRE].
M.E. Peskin, Estimation of LHC and ILC capabilities for precision Higgs boson coupling measurements, arXiv:1312.4974 [INSPIRE].
M.E. Peskin, Comparison of LHC and ILC capabilities for Higgs boson coupling measurements, arXiv:1207.2516 [INSPIRE].
CMS collaboration, Constraints on the Higgs boson width from off-shell production and decay to Z-boson pairs, Phys. Lett. B 736 (2014) 64 [arXiv:1405.3455] [INSPIRE].
ATLAS collaboration, Constraints on the off-shell Higgs boson signal strength in the high-mass ZZ and W W final states with the ATLAS detector, Eur. Phys. J. C 75 (2015) 335 [arXiv:1503.01060] [INSPIRE].
C. Englert, Y. Soreq and M. Spannowsky, Off-shell Higgs coupling measurements in BSM scenarios, JHEP 05 (2015) 145 [arXiv:1410.5440] [INSPIRE].
C. Englert and M. Spannowsky, Limitations and opportunities of off-shell coupling measurements, Phys. Rev. D 90 (2014) 053003 [arXiv:1405.0285] [INSPIRE].
P.P. Giardino, K. Kannike, I. Masina, M. Raidal and A. Strumia, The universal Higgs fit, JHEP 05 (2014) 046 [arXiv:1303.3570] [INSPIRE].
CMS collaboration, Search for lepton-flavour-violating decays of the Higgs boson, Phys. Lett. B 749 (2015) 337 [arXiv:1502.07400] [INSPIRE].
CMS collaboration, Search for lepton-flavour-violating decays of the Higgs boson to eτ and eμ at \( \sqrt{s}=8 \) TeV, CMS-PAS-HIG-14-040 (2014).
https://indico.in2p3.fr/event/12279/session/5/contribution/202/material/slides/0.pdf
ATLAS collaboration, Search for lepton-flavour-violating H → μτ decays of the Higgs boson with the ATLAS detector, JHEP 11 (2015) 211 [arXiv:1508.03372] [INSPIRE].
G. Blankenburg, J. Ellis and G. Isidori, Flavour-changing decays of a 125 GeV Higgs-like particle, Phys. Lett. B 712 (2012) 386 [arXiv:1202.5704] [INSPIRE].
R. Harnik, J. Kopp and J. Zupan, Flavor violating Higgs decays, JHEP 03 (2013) 026 [arXiv:1209.1397] [INSPIRE].
H. Bélusca-Maïto and A. Falkowski, On the exotic Higgs decays in effective field theory, arXiv:1602.02645 [INSPIRE].
I. Doršner et al., New physics models facing lepton flavor violating Higgs decays at the percent level, JHEP 06 (2015) 108 [arXiv:1502.07784] [INSPIRE].
A. Arhrib, Y. Cheng and O.C.W. Kong, Comprehensive analysis on lepton flavor violating Higgs boson to μ ∓ τ ± decay in supersymmetry without R parity, Phys. Rev. D 87 (2013) 015025 [arXiv:1210.8241] [INSPIRE].
A. Abada, M.E. Krauss, W. Porod, F. Staub, A. Vicente and C. Weiland, Lepton flavor violation in low-scale seesaw models: SUSY and non-SUSY contributions, JHEP 11 (2014) 048 [arXiv:1408.0138] [INSPIRE].
E. Arganda, M.J. Herrero, X. Marcano and C. Weiland, Enhancement of the lepton flavor violating Higgs boson decay rates from SUSY loops in the inverse seesaw model, Phys. Rev. D 93 (2016) 055010 [arXiv:1508.04623] [INSPIRE].
E. Arganda, M.J. Herrero, R. Morales and A. Szynkman, Analysis of the h, H, A → τ μ decays induced from SUSY loops within the mass insertion approximation, JHEP 03 (2016) 055 [arXiv:1510.04685] [INSPIRE].
C. Alvarado, R.M. Capdevilla, A. Delgado and A. Martin, Minimal models of loop-induced Higgs lepton flavor violation, arXiv:1602.08506 [INSPIRE].
D. Das and A. Kundu, Two hidden scalars around 125 GeV and h → μτ , Phys. Rev. D 92 (2015) 015009 [arXiv:1504.01125] [INSPIRE].
M. Arroyo, J.L. Diaz-Cruz, E. Diaz and J.A. Orduz-Ducuara, Flavor violating Higgs signals in the texturized two-Higgs doublet model (2HDM-Tx), arXiv:1306.2343 [INSPIRE].
J. Kopp and M. Nardecchia, Flavor and CP-violation in Higgs decays, JHEP 10 (2014) 156 [arXiv:1406.5303] [INSPIRE].
D. Aristizabal Sierra and A. Vicente, Explaining the CMS Higgs flavor violating decay excess, Phys. Rev. D 90 (2014) 115004 [arXiv:1409.7690] [INSPIRE].
A. Crivellin, G. D’Ambrosio and J. Heeck, Explaining h → μ ± τ ∓ , B → K ∗ μ + μ − and B → Kμ + μ − /B → Ke + e − in a two-Higgs-doublet model with gauged L μ −L τ , Phys. Rev. Lett. 114 (2015) 151801 [arXiv:1501.00993] [INSPIRE].
L. de Lima, C.S. Machado, R.D. Matheus and L.A.F. do Prado, Higgs flavor violation as a signal to discriminate models, JHEP 11 (2015) 074 [arXiv:1501.06923] [INSPIRE].
S.P. Das, J. Hernández-Sánchez, S. Moretti, A. Rosado and R. Xoxocotzi, Flavor violating signatures of lighter and heavier Higgs bosons within the Two Higgs Doublet Model Type-III at the LHeC, arXiv:1503.01464 [INSPIRE].
Y.-n. Mao and S.-h. Zhu, Higgs boson-μ-τ coupling at high and low energy colliders, Phys. Rev. D 93 (2016) 035014 [arXiv:1505.07668] [INSPIRE].
F.J. Botella, G.C. Branco, M. Nebot and M.N. Rebelo, Flavour changing Higgs couplings in a class of two Higgs doublet models, Eur. Phys. J. C 76 (2016) 161 [arXiv:1508.05101] [INSPIRE].
R. Benbrik, C.-H. Chen and T. Nomura, h, \( Z\to {\ell}_i{\overline{\ell}}_j \) , Δa μ , τ → (3μ, μγ) in generic two-Higgs-doublet models, Phys. Rev. D 93 (2016) 095004 [arXiv:1511.08544] [INSPIRE].
Y. Omura, E. Senaha and K. Tobe, τ - and μ-physics in a general two Higgs doublet model with μ − τ flavor violation, arXiv:1511.08880 [INSPIRE].
H.-B. Zhang, T.-F. Feng, S.-M. Zhao, Y.-L. Yan and F. Sun, 125 GeV Higgs decay with lepton flavor violation in the μνSSM, arXiv:1511.08979 [INSPIRE].
N. Bizot, S. Davidson, M. Frigerio and J.L. Kneur, Two Higgs doublets to explain the excesses pp → γγ(750 GeV) and h → τ ± μ ∓, JHEP 03 (2016) 073 [arXiv:1512.08508] [INSPIRE].
M. Buschmann, J. Kopp, J. Liu and X.-P. Wang, New signatures of flavor violating Higgs couplings, JHEP 06 (2016) 149 [arXiv:1601.02616] [INSPIRE].
M. Sher and K. Thrasher, Flavor changing leptonic decays of heavy Higgs bosons, Phys. Rev. D 93 (2016) 055021 [arXiv:1601.03973] [INSPIRE].
X.-F. Han, L. Wang and J.M. Yang, An extension of two-Higgs-doublet model and the excesses of 750 GeV diphoton, muon g − 2 and h → μτ , Phys. Lett. B 757 (2016) 537 [arXiv:1601.04954] [INSPIRE].
A. Crivellin, S. Najjari and J. Rosiek, Lepton flavor violation in the standard model with general dimension-six operators, JHEP 04 (2014) 167 [arXiv:1312.0634] [INSPIRE].
A. Crivellin, M. Hoferichter and M. Procura, Improved predictions for μ → e conversion in nuclei and Higgs-induced lepton flavor violation, Phys. Rev. D 89 (2014) 093024 [arXiv:1404.7134] [INSPIRE].
A. Dery, A. Efrati, Y. Nir, Y. Soreq and V. Susič, Model building for flavor changing Higgs couplings, Phys. Rev. D 90 (2014) 115022 [arXiv:1408.1371] [INSPIRE].
M.D. Campos, A.E. Cárcamo Hernández, H. Päs and E. Schumacher, Higgs → μτ as an indication for S 4 flavor symmetry, Phys. Rev. D 91 (2015) 116011 [arXiv:1408.1652] [INSPIRE].
J. Heeck, M. Holthausen, W. Rodejohann and Y. Shimizu, Higgs → μτ in abelian and non-abelian flavor symmetry models, Nucl. Phys. B 896 (2015) 281 [arXiv:1412.3671] [INSPIRE].
X.-G. He, J. Tandean and Y.-J. Zheng, Higgs decay h → μτ with minimal flavor violation, JHEP 09 (2015) 093 [arXiv:1507.02673] [INSPIRE].
K. Cheung, W.-Y. Keung and P.-Y. Tseng, Leptoquark induced rare decay amplitudes h → τ ∓ μ ± and τ → μγ, Phys. Rev. D 93 (2016) 015010 [arXiv:1508.01897] [INSPIRE].
F. Feruglio, P. Paradisi and A. Pattori, Lepton flavour violation in composite Higgs models, Eur. Phys. J. C 75 (2015) 579 [arXiv:1509.03241] [INSPIRE].
D. Delepine, M. Napsuciale and E. Peinado, Effects of an H-μ-τ coupling in quarkonium lepton flavor violation decays, arXiv:1509.04057 [INSPIRE].
N. Košnik, New physics models facing lepton flavor violating Higgs decays, arXiv:1509.04590 [INSPIRE].
S. Baek and K. Nishiwaki, Leptoquark explanation of h → μτ and muon (g − 2), Phys. Rev. D 93 (2016) 015002 [arXiv:1509.07410] [INSPIRE].
S. Baek and Z.-F. Kang, Naturally large radiative lepton flavor violating Higgs decay mediated by lepton-flavored dark matter, JHEP 03 (2016) 106 [arXiv:1510.00100] [INSPIRE].
L.T. Hue, H.N. Long, T.T. Thuc and T. Phong Nguyen, Lepton flavor violating decays of standard-model-like Higgs in 3-3-1 model with neutral lepton, Nucl. Phys. B 907 (2016) 37 [arXiv:1512.03266] [INSPIRE].
C.-F. Chang, C.-H.V. Chang, C.S. Nugroho and T.-C. Yuan, Lepton flavor violating decays of neutral Higgses in extended mirror fermion model, arXiv:1602.00680 [INSPIRE].
S. Davidson and P. Verdier, LHC sensitivity to the decay h → τ ± mu ∓, Phys. Rev. D 86 (2012) 111701 [arXiv:1211.1248] [INSPIRE].
D. Curtin et al., Exotic decays of the 125 GeV Higgs boson, Phys. Rev. D 90 (2014) 075004 [arXiv:1312.4992] [INSPIRE].
S. Bressler, A. Dery and A. Efrati, Asymmetric lepton-flavor violating Higgs boson decays, Phys. Rev. D 90 (2014) 015025 [arXiv:1405.4545] [INSPIRE].
C.-X. Yue, C. Pang and Y.-C. Guo, Lepton flavor violating Higgs couplings and single production of the Higgs boson via eγ collision, J. Phys. G 42 (2015) 075003 [arXiv:1505.02209] [INSPIRE].
B. Bhattacherjee, S. Chakraborty and S. Mukherjee, H → τ μ and excess in \( t\overline{t}H \) : connecting the dots in the hope for the first glimpse of BSM Higgs signal, arXiv:1505.02688 [INSPIRE].
Particle Data Group collaboration, J. Beringer et al., Review of particle physics, Phys. Rev. D 86 (2012) 010001 [INSPIRE].
MEG collaboration, J. Adam et al., New constraint on the existence of the μ + → e + γ decay, Phys. Rev. Lett. 110 (2013) 201801 [arXiv:1303.0754] [INSPIRE].
L. Willmann et al., New bounds from searching for muonium to anti-muonium conversion, Phys. Rev. Lett. 82 (1999) 49 [hep-ex/9807011] [INSPIRE].
T.E. Clark and S.T. Love, Muonium-anti-muonium oscillations and massive Majorana neutrinos, Mod. Phys. Lett. A 19 (2004) 297 [hep-ph/0307264] [INSPIRE].
Particle Data Group collaboration, K. Nakamura et al., Review of particle physics, J. Phys. G 37 (2010) 075021 [INSPIRE].
Muon g-2 collaboration, G.W. Bennett et al., Final report of the muon E821 anomalous magnetic moment measurement at BNL, Phys. Rev. D 73 (2006) 072003 [hep-ex/0602035] [INSPIRE].
A. van der Schaaf, Sindrum II, J. Phys. G 29 (2003) 1503 [INSPIRE].
DELPHI, OPAL, ALEPH, LEP Electroweak Working Group, L3 collaboration, J. Alcaraz et al., A combination of preliminary electroweak measurements and constraints on the standard model, hep-ex/0612034 [INSPIRE].
W. Altmannshofer, J. Brod and M. Schmaltz, Experimental constraints on the coupling of the Higgs boson to electrons, JHEP 05 (2015) 125 [arXiv:1503.04830] [INSPIRE].
T. Han and B. McElrath, h → μ + μ − via gluon fusion at the LHC, Phys. Lett. B 528 (2002) 81 [hep-ph/0201023] [INSPIRE].
http://www.bo.infn.it/∼giacomel/talks/Higgs-Physics-prospects-LHC-LTS1-Elba-22-05-14- pg.pdf
ATLAS collaboration, Projections for measurements of Higgs boson cross sections, branching ratios and coupling parameters with the ATLAS detector at a HL-LHC, ATL-PHYS-PUB-2013-014 (2013).
MEG collaboration, F. Renga, Latest results of MEG and status of MEG-II, DESY-PROC-2014-04 (2015).
Belle-II collaboration, B. Wang, The Belle II experiment and SuperKEKB upgrade, arXiv:1511.09434 [INSPIRE].
C. Delaunay, R. Ozeri, G. Perez and Y. Soreq, Probing the atomic Higgs force, arXiv:1601.05087 [INSPIRE].
C. Delaunay and Y. Soreq, Probing new physics with isotope shift spectroscopy, arXiv:1602.04838 [INSPIRE].
C. Frugiuele, E. Fuchs, G. Perez and M. Schlaffer, Atomic probes of new physics, arXiv:1602.04822 [INSPIRE].
Mu2e collaboration, R.J. Abrams et al., Mu2e conceptual design report, arXiv:1211.7019 [INSPIRE].
A. Alloul, N.D. Christensen, C. Degrande, C. Duhr and B. Fuks, FeynRules 2.0 — A complete toolbox for tree-level phenomenology, Comput. Phys. Commun. 185 (2014) 2250 [arXiv:1310.1921] [INSPIRE].
C. Degrande et al., UFO — The Universal FeynRules Output, Comput. Phys. Commun. 183 (2012) 1201 [arXiv:1108.2040] [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].
S. Jadach, Z. Was, R. Decker and J.H. Kuhn, The τ decay library TAUOLA: version 2.4, Comput. Phys. Commun. 76 (1993) 361 [INSPIRE].
DELPHES 3 collaboration, J. de Favereau et al., DELPHES 3, a modular framework for fast simulation of a generic collider experiment, JHEP 02 (2014) 057 [arXiv:1307.6346] [INSPIRE].
M. Cacciari, G.P. Salam and G. Soyez, The anti-k t jet clustering algorithm, JHEP 04 (2008) 063 [arXiv:0802.1189] [INSPIRE].
M. Cacciari, G.P. Salam and G. Soyez, FastJet user manual, Eur. Phys. J. C 72 (2012) 1896 [arXiv:1111.6097] [INSPIRE].
CMS collaboration, τ identification in CMS, CMS-PAS-TAU-11-001 (2011).
R. Boughezal, X. Liu and F. Petriello, Phenomenology of the Z-boson plus jet process at NNLO, arXiv:1602.08140 [INSPIRE].
J.M. Campbell, R.K. Ellis and C. Williams, Vector boson pair production at the LHC, JHEP 07 (2011) 018 [arXiv:1105.0020] [INSPIRE].
J.M. Campbell, R.K. Ellis and D.L. Rainwater, Next-to-leading order QCD predictions for W +2 jet and Z+2 jet production at the CERN LHC,Phys. Rev. D 68 (2003) 094021 [hep-ph/0308195] [INSPIRE].
S. Catani, L. Cieri, G. Ferrera, D. de Florian and M. Grazzini, Vector boson production at hadron colliders: a fully exclusive QCD calculation at NNLO, Phys. Rev. Lett. 103 (2009) 082001 [arXiv:0903.2120] [INSPIRE].
C. Muselli, M. Bonvini, S. Forte, S. Marzani and G. Ridolfi, Top quark pair production beyond NNLO, JHEP 08 (2015) 076 [arXiv:1505.02006] [INSPIRE].
P. Kant et al., HatHor for single top-quark production: updated predictions and uncertainty estimates for single top-quark production in hadronic collisions, Comput. Phys. Commun. 191 (2015) 74 [arXiv:1406.4403] [INSPIRE].
A. Hocker et al., TMVA — Toolkit for Multivariate Data Analysis with ROOT, PoS(ACAT)040 [physics/0703039] [INSPIRE].
D. Ciupke, Study of BDT training configurations with an application to the Z/H → τ τ → ee Analysis, http://www.desy.de/f/students/2012/reports/david ciupke.pdf.gz (2012).
D.M. Asner et al., ILC Higgs white paper, arXiv:1310.0763 [INSPIRE].
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.
Author information
Authors and Affiliations
Corresponding author
Additional information
ArXiv ePrint: 1603.05952
Rights and permissions
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0), which permits use, duplication, adaptation, distribution, and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
About this article
Cite this article
Banerjee, S., Bhattacherjee, B., Mitra, M. et al. The lepton flavour violating Higgs decays at the HL-LHC and the ILC. J. High Energ. Phys. 2016, 59 (2016). https://doi.org/10.1007/JHEP07(2016)059
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/JHEP07(2016)059