Top quark anomalous couplings from top-pair tagged photoproduction at pe− colliders


  • Antonio Bouzas Cinvestav Mérida
  • F. Larios Cinvestav Mérida



Top-quark; photoproduction; electron-proton-collider


We summarize the quantitative results of our analysis [1] of top-pair photoproduction in semileptonic mode in pe collisions at the LHeC and FCC-he. We define three photoproduction regions, based on the rapidity acceptance range of the electron tagger, that provide different degrees of sensitivity to top-quark effective couplings. We focus on the ttγ dipole couplings and the left-handed vector tbW coupling, for which we determine limits at both energies in the different photoproduction regions. Furthermore, we find that the LHeC and FCC-he will yield tight direct bounds on top dipole moments, greatly improving on current direct limits from hadron colliders, and direct limits on the tbW coupling as restrictive as those expected from the HL-LHC. We also consider indirect limits from b → sγ branching ratio and CP asymmetry, that are well known to be very sensitive probes of top electromagnetic dipole moments.


A. Bouzas, F. Larios, Top quark effective couplings from top-pair tagged photoproduction in pe− collisions, Phys. Rev. D 105 (2022) 115002, [arXiv:2111.04723 [hep-ph]

P. Agostini et al. [LHeC and FCC-he Study Group], The Large Hadron-Electron Collider at the HL-LHC, J. Phys. G 48 (2021) 110501, [arXiv:2007.14491 [hep-ex]]

Q. H. Cao, B. Yan, C. P. Yuan and Y. Zhang, Probing Ztt couplings using Z boson polarization in ZZ production at hadron colliders, Phys. Rev. D 102 (2020) 055010, [arXiv:2004.02031 [hep-ph]]

A. Kozachuk and D. Melikhov, Constraints on the anomalous W tb couplings from B-physics experiments, Symmetry 12 (2020) 1506, [arXiv:2004.13127 [hep-ph]]

I. A. Sarmiento-Alvarado, Antonio O. Bouzas, F. Larios, Analysis of top-quark charged-current coupling at the LHeC, J. Phys. G 42 (2015) 085001, [arXiv:1412.6679 [hep-ph]]

S. Dutta, A. Goyal, M. Kumar and B. Mellado, Measuring anomalous W tb couplings at e −p collider, Eur. Phys. J. C 75 (2015) 577, [arXiv:1307.1688 [hep-ph]]

A. Bouzas, F. Larios, Probing ttγ and ttZ couplings at the LHeC, Phys. Rev. D 88 (2013) 094007, [arXiv:1308.5634 [hep-ph]]

A. A. Billur, M. Köksal and A. Gutiérrez-Rodríguez, Improved sensitivity on the electromagnetic dipole moments of the top quark in γγ, γγ∗ and γ ∗ γ ∗ collisions at the CLIC, Phys. Rev. D 96 (2017) 056007, [arXiv:1702.03708 [hep-ph]]

M. Köksal, A. A. Billur, A. Gutiérrez-Rodríguez and M. A. Hernández-Ruíz, Sensitivity measuring expected on the electromagnetic anomalous couplings in the ttγ vertex at the FCC-he, Int. J. Mod. Phys. A 35 (2020) 2050178, doi: 10.1142/S0217751X2050178X [arXiv:1905.02564 [hepph]]

A. Bouzas, F. Larios, Electromagnetic dipole moments of the top quark, Phys. Rev. D 87 (2013) 074015, [arXiv:1212.6575 [hep-ph]]

J. L. Hewett and T. G. Rizzo, Using b → sγ to probe top quark couplings, Phys. Rev. D 49 (1994) 319, doi:10.1103/PhysRevD.49.319 [arXiv:hep-ph/9305223 [hep-ph]]

J. Aebischer et al., Matching of gauge invariant dimension-six operators for b → s and b → c transitions, JHEP 2016 (2016) 37,

V. Khachatryan et al., Search for anomalous W tb couplings and flavour-changing neutral currents in t-channel single top quark production in pp collisions at √ s = 7 and 8 TeV, JHEP 2017 (2017) 028,

A. Tumasyan et al., Measurement of the inclusive and differential ttγ cross sections in the dilepton channel and effective field theory interpretation in proton-proton collisions at √ s = 13 TeV, JHEP 2022 (2022) 091,

ATLAS collaboration, Prospects for the measurement of ttγ with the upgraded ATLAS detector at the High-Luminosity LHC, CERN report ATL-PHYS-PUB-2018-049, Dec. 2018

B. Grzadkowski et al., Dimension-six Terms in the Standard Model Lagrangian, JHEP 2010 (2010) 85,

C. Zhang, Effective field theory approach to top-quark decay at next-to-leading order in QCD, Phys. Rev. D 90 (2014) 014008, [arXiv:1404.1264 [hep-ph]]

E. E. Jenkins, A. V. Manohar and M. Trott, Naive Dimensional Analysis Counting of Gauge Theory Amplitudes and Anomalous Dimensions, Phys. Lett. B 726 (2013) 697, [arXiv:1309.0819 [hep-ph]]

J. A. Aguilar Saavedra et al., Interpreting top-quark LHC measurements in the standard-model effective field theory, (2018),

V. M. Budnev, I. F. Ginzburg, G. V. Meledin, V. G. Serbo, The two photon particle production mechanism. Physical problems. Applications. Equivalent photon approximation, Phys. Rep. 15 (1975) 181,

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, J. High Energy Phys. 2014 (2014) 079,

T. Sjöstrand, S. Mrenna, and P. Skands, Pythia 6.4 Physics and Manual, J. High Energy Phys. 2006 (2006) 26,

J. de Favereau et al., DELPHES 3: a modular framework for fast simulation of a generic collider experiment, J. High Energy Phys. 2014 (2014) 57,

A. Arishev et al., (The ILC International Development Team), The International Linear Collider: Report to Snowmass 2021, (2023),

F. Richard, Present and future constraints on top EW couplings (2014),

C. F. Berger, M. Perelstein and F. Petriello, Top quark properties in little Higgs models, (2005),

C. Grojean, O. Matsedonskyi and G. Panico, Light top partners and precision physics, JHEP 2013 (2013) 160,

G. Durieux and O. Matsedonskyi, The top-quark window on compositeness at future lepton colliders, JHEP 2019 (2019) 072,




How to Cite

Bouzas A, Larios F. Top quark anomalous couplings from top-pair tagged photoproduction at pe− colliders. Supl. Rev. Mex. Fis. [Internet]. 2024 Jan. 19 [cited 2024 Mar. 2];4(2):021132 1-7. Available from: