- Physical Review Journals
All JournalsPhysics Magazine

Physical Review D

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Open Access

Prospects for sub-EW-scale ALP searches via γ+bb¯ signatures at the LHC using jet substructure techniques

Amit Adhikary1,*, Aoife Bharucha1, Lorenzo Feligioni2, and Michele Frigerio3

  • *Contact author: amit.adhikary@cpt.univ-mrs.fr
PDF

Phys. Rev. D 112, 055042 – Published 29 September, 2025

DOI: https://doi.org/10.1103/bf6h-573f

Abstract

The current Large Hadron Collider (LHC) data show no clear indication of new physics and only incremental improvements are anticipated at the energy frontier in the near future. However, while the focus of the LHC has been on constraining TeV scale physics, new particles could still be hiding below the electroweak scale. In order to obtain sensitivity to a new light boson with couplings to SM fermions, a potentially promising decay channel, for resonances with mass ≳O(10)  GeV, would be the decay to bb¯ pairs. The measurement of such signatures is challenging due to the trigger requirements at the LHC. In this work, we explore the LHC sensitivity to a light pseudoscalar, or axionlike particle (ALP), in the bb¯ final state with an associated photon, using jet substructure techniques, in the mass range between 10 and 100 GeV. We obtain projected exclusions on the ALP-fermion coupling in a region of phase space which has not so far been probed by direct searches. We further discuss the impact that lower trigger thresholds may have on the LHC reach.

View figure in article

Physics Subject Headings (PhySH)

Article Text

References (95)

  1. J. Jaeckel and A. Ringwald, The low-energy frontier of particle physics, Annu. Rev. Nucl. Part. Sci. 60, 405 (2010).
  2. L. Di Luzio, M. Giannotti, E. Nardi, and L. Visinelli, The landscape of QCD axion models, Phys. Rep. 870, 1 (2020).
  3. I. Brivio, M. B. Gavela, L. Merlo, K. Mimasu, J. M. No, R. del Rey et al., ALPs effective field theory and collider signatures, Eur. Phys. J. C 77, 572 (2017).
  4. M. Bauer, M. Neubert, and A. Thamm, Collider probes of axion-like particles, J. High Energy Phys. 12 (2017) 044.
  5. Particle Data Group, Review of particle physics, Phys. Rev. D 110, 030001 (2024).
  6. X. Chu, T. Hambye, and M. H. Tytgat, The four basic ways of creating dark matter through a portal, J. Cosmol. Astropart. Phys. 05 (2012) 034.
  7. C. Boehm, M. J. Dolan, C. McCabe, M. Spannowsky, and C. J. Wallace, Extended gamma-ray emission from coy dark matter, J. Cosmol. Astropart. Phys. 05 (2014) 009.
  8. C. Arina, E. Del Nobile, and P. Panci, Dark matter with pseudoscalar-mediated interactions explains the DAMA signal and the Galactic Center excess, Phys. Rev. Lett. 114, 011301 (2015).
  9. T. Hambye, M. H. G. Tytgat, J. Vandecasteele, and L. Vanderheyden, Dark matter from dark photons: A taxonomy of dark matter production, Phys. Rev. D 100, 095018 (2019).
  10. A. Bharucha, F. Brümmer, N. Desai, and S. Mutzel, Axion-like particles as mediators for dark matter: Beyond freeze-out, J. High Energy Phys. 02 (2023) 141.
  11. U. Ellwanger, C. Hugonie, and A. M. Teixeira, The next-to-minimal supersymmetric standard model, Phys. Rep. 496, 1 (2010).
  12. B. Bellazzini, A. Mariotti, D. Redigolo, F. Sala, and J. Serra, R-axion at colliders, Phys. Rev. Lett. 119, 141804 (2017).
  13. B. Gripaios, A. Pomarol, F. Riva, and J. Serra, Beyond the minimal composite Higgs model, J. High Energy Phys. 04 (2009) 070.
  14. M. Frigerio, A. Pomarol, F. Riva, and A. Urbano, Composite scalar dark matter, J. High Energy Phys. 07 (2012) 015.
  15. G. Cacciapaglia, G. Ferretti, T. Flacke, and H. Serôdio, Light scalars in composite Higgs models, Front. Phys. 7, 22 (2019).
  16. D. Buarque Franzosi, G. Cacciapaglia, X. Cid Vidal, G. Ferretti, T. Flacke, and C. Vázquez Sierra, Exploring new possibilities to discover a light pseudo-scalar at LHCb, Eur. Phys. J. C 82, 3 (2022).
  17. D. Elander, M. Frigerio, M. Knecht, and J.-L. Kneur, Holographic models of composite Higgs in the Veneziano limit. Part I. Bosonic sector, J. High Energy Phys. 03 (2021) 182.
  18. ATLAS Collaboration, Search for low-mass dijet resonances using trigger-level jets with the ATLAS detector in pp collisions at s=13  TeV, Phys. Rev. Lett. 121, 081801 (2018).
  19. CMS Collaboration, Search for low mass vector resonances decaying into quark-antiquark pairs in proton-proton collisions at s=13  TeV, Phys. Rev. D 100, 112007 (2019).
  20. M. Cacciari, G. P. Salam, and G. Soyez, The anti-kt jet clustering algorithm, J. High Energy Phys. 04 (2008) 063.
  21. CMS Collaboration, Search for low-mass quark-antiquark resonances produced in association with a photon at s=13  TeV, Phys. Rev. Lett. 123, 231803 (2019).
  22. ATLAS Collaboration, Search for light resonances decaying to boosted quark pairs and produced in association with a photon or a jet in proton-proton collisions at s=13  TeV with the ATLAS detector, Phys. Lett. B 788, 316 (2019).
  23. ATLAS Collaboration, Search for low-mass resonances decaying into two jets and produced in association with a photon using pp collisions at s=13  TeV with the ATLAS detector, Phys. Lett. B 795, 56 (2019).
  24. CMS Collaboration, Search for low-mass resonances decaying into bottom quark-antiquark pairs in proton-proton collisions at s=13  TeV, Phys. Rev. D 99, 012005 (2019).
  25. ATLAS Collaboration, Expected performance of the ATLAS detector at the High-Luminosity LHC, Technical Report No. ATL-PHYS-PUB-2019-005, CERN, Geneva, 2019.
  26. CMS Collaboration, Expected performance of the physics objects with the upgraded CMS detector at the HL-LHC, Technical Report Nos. CMS-NOTE-2018-006, CERN-CMS-NOTE-2018-006, CERN, Geneva, 2018.
  27. J. Quevillon and C. Smith, Axions are blind to anomalies, Eur. Phys. J. C 79, 822 (2019).
  28. M. Bauer, M. Neubert, S. Renner, M. Schnubel, and A. Thamm, The low-energy effective theory of axions and ALPs, J. High Energy Phys. 04 (2021) 063.
  29. F. Arias-Aragón, J. Quevillon, and C. Smith, Axion-like ALPs, J. High Energy Phys. 03 (2023) 134.
  30. A. Biekötter, J. Fuentes-Martín, A. M. Galda, and M. Neubert, A global analysis of axion-like particle interactions using SMEFT fits, J. High Energy Phys. 09 (2023) 120.
  31. D. K. Ghosh, A. Ghoshal, and S. Jeesun, Axion-like particle (ALP) portal freeze-in dark matter confronting ALP search experiments, J. High Energy Phys. 01 (2024) 026.
  32. X. Cid Vidal, A. Mariotti, D. Redigolo, F. Sala, and K. Tobioka, New axion searches at flavor factories, J. High Energy Phys. 01 (2019) 113.
  33. K. Nishijima, Generalized Furry’s thorem for closed loops, Prog. Theor. Phys. 6, 614 (1951).
  34. S. Catani, M. Fontannaz, J. P. Guillet, and E. Pilon, Cross-section of isolated prompt photons in hadron hadron collisions, J. High Energy Phys. 05 (2002) 028.
  35. Sherpa Collaboration, Event generation with Sherpa 3, J. High Energy Phys. 12 (2024) 156.
  36. ATLAS Collaboration, Measurement of the inclusive isolated prompt photon cross section in pp collisions at s=8  TeV with the ATLAS detector, J. High Energy Phys. 08 (2016) 005.
  37. ATLAS Collaboration, Inclusive-photon production and its dependence on photon isolation in pp collisions at s=13  TeV using 139  fb−1 of ATLAS data, J. High Energy Phys. 07 (2023) 086.
  38. CMS Collaboration, Search for low mass vector resonances decaying into quark-antiquark pairs in proton-proton collisions at s=13  TeV, J. High Energy Phys. 01 (2018) 097.
  39. J. Alwall, R. Frederix, S. Frixione, V. Hirschi, F. Maltoni, O. Mattelaer 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. 07 (2014) 079.
  40. T. Sjöstrand, S. Ask, J. R. Christiansen, R. Corke, N. Desai, P. Ilten, S. Mrenna, S. Prestel, C. O. Rasmussen, and P. Z. Skands , An introduction to pythia 8.2, Comput. Phys. Commun. 191, 159 (2015).
  41. The ATLAS Collaboration, ATLAS pythia 8 tunes to 7 TeV data, Technical Report No. ATL-PHYS-PUB-2014-021, CERN, Geneva, 2014.
  42. NNPDF Collaboration, Parton distributions for the LHC Run II, J. High Energy Phys. 04 (2015) 040.
  43. DELPHES 3 Collaboration, delphes 3, A modular framework for fast simulation of a generic collider experiment, J. High Energy Phys. 02 (2014) 057.
  44. M. Cacciari, G. P. Salam, and G. Soyez, FastJet user manual, Eur. Phys. J. C 72, 1896 (2012).
  45. A. J. Larkoski, S. Marzani, G. Soyez, and J. Thaler, Soft drop, J. High Energy Phys. 05 (2014) 146.
  46. ATLAS Collaboration, Identification of hadronically-decaying top quarks using UFO jets with ATLAS in Run 2, Technical Report No. ATL-PHYS-PUB-2021-028, CERN, Geneva, 2021.
  47. ATLAS Collaboration, Recommendations for the modeling of smooth backgrounds, Technical Report No. ATL-PHYS-PUB-2020-028, CERN, Geneva, 2020.
  48. J. Dolen, P. Harris, S. Marzani, S. Rappoccio, and N. Tran, Thinking outside the ROCs: Designing decorrelated taggers (DDT) for jet substructure, J. High Energy Phys. 05 (2016) 156.
  49. I. Moult, L. Necib, and J. Thaler, New angles on energy correlation functions, J. High Energy Phys. 12 (2016) 153.
  50. S. A. Dudani, The distance-weighted k-nearest-neighbor rule, IEEE Trans. Syst., Man., Cybern. SMC-6, 325 (1976).
  51. ATLAS Collaboration, Optimisation and performance studies of the ATLAS b-tagging algorithms for the 2017-18 LHC run, Technical Report No. ATL-PHYS-PUB-2017-013, CERN, Geneva, 2017.
  52. CMS Collaboration, Identification of heavy-flavour jets with the CMS detector in pp collisions at 13 TeV, J. Instrum. 13, P05011 (2018).
  53. ATLAS Collaboration, ATLAS b-jet identification performance and efficiency measurement with tt¯ events in pp collisions at s=13  TeV, Eur. Phys. J. C 79, 970 (2019).
  54. ATLAS Collaboration, Boosted Higgs (→bb¯) boson identification with the ATLAS detector at s=13  TeV, Technical Report No. ATLAS-CONF-2016-039, CERN, Geneva, 2016.
  55. ATLAS Collaboration, Search for supersymmetry in events with b-tagged jets and missing transverse momentum in pp collisions at s=13  TeV with the ATLAS detector, J. High Energy Phys. 11 (2017) 195.
  56. CMS Collaboration, Search for supersymmetry in final states with b jets and missing energy at the LHC, Technical Report No. CMS-PAS-SUS-10-011, CERN, Geneva, 2011.
  57. CMS Collaboration, Inclusive search for highly boosted Higgs bosons decaying to bottom quark-antiquark pairs in proton-proton collisions at s=13  TeV, J. High Energy Phys. 12 (2020) 085.
  58. CMS Collaboration, Search for supersymmetry in the all-hadronic final state using top quark tagging in pp collisions at s=13  TeV, Phys. Rev. D 96, 012004 (2017).
  59. ATLAS Collaboration, Transformer neural networks for identifying boosted Higgs bosons decaying into bb¯ and cc¯ in ATLAS, Technical Report No. ATL-PHYS-PUB-2023-021, CERN, Geneva, 2023.
  60. ATLAS Collaboration, Expected performance of the ATLAS b-tagging algorithms in Run-2, Technical Report No. ATL-PHYS-PUB-2015-022, CERN, Geneva, 2015.
  61. CMS Collaboration, Identification of b-quark jets with the CMS experiment, J. Instrum. 8, P04013 (2013).
  62. D. Krohn, J. Thaler, and L.-T. Wang, Jets with variable R, J. High Energy Phys. 06 (2009) 059.
  63. ATLAS Collaboration, Variable radius, exclusive-kT, and center-of-mass subjet reconstruction for Higgs(→bb¯) tagging in ATLAS, Technical Report No. ATL-PHYS-PUB-2017-010, CERN, Geneva, 2017.
  64. S. Catani, Y. Dokshitzer, M. Seymour, and B. Webber, Longitudinally-invariant kt-clustering algorithms for hadron-hadron collisions, Nucl. Phys. B406, 187 (1993).
  65. M. Wobisch and T. Wengler, Hadronization corrections to jet cross-sections in deep inelastic scattering, in Proceedings of the Workshop on Monte Carlo Generators for HERA Physics (Plenary Starting Meeting) (1998), pp. 270–279, arXiv:hep-ph/9907280.
  66. ATLAS Collaboration, Identification of boosted Higgs bosons decaying into bb¯ with neural networks and variable radius subjets in ATLAS, Technical Report No. ATL-PHYS-PUB-2020-019, CERN, Geneva, 2020.
  67. M. Oreglia, A study of the reactions ψ′→γγψ, other thesis, SLAC National Accelerator Laboratory, 1980.
  68. The ATLAS Collaboration, Search for scalar diphoton resonances in the mass range 65–600 GeV with the ATLAS detector in pp collision data at s=8  TeV, Technical Report No. ATLAS-CONF-2014-031, CERN, Geneva, 2014.
  69. G. Cowan, K. Cranmer, E. Gross, and O. Vitells, Asymptotic formulae for likelihood-based tests of new physics, Eur. Phys. J. C 71, 1554 (2011).
  70. G. Cowan, Discovery sensitivity for a counting experiment with background uncertainty, Technical Report, Royal Holloway, London (2012).
  71. K. J. Kelly, S. Kumar, and Z. Liu, Heavy axion opportunities at the DUNE near detector, Phys. Rev. D 103, 095002 (2021).
  72. F. Ertas and F. Kahlhoefer, On the interplay between astrophysical and laboratory probes of MeV-scale axion-like particles, J. High Energy Phys. 07 (2020) 050.
  73. M. Pospelov, A. Ritz, and M. B. Voloshin, Bosonic super-WIMPs as keV-scale dark matter, Phys. Rev. D 78, 115012 (2008).
  74. F. T. Avignone, III, R. L. Brodzinski, S. Dimopoulos, G. D. Starkman, A. K. Drukier, D. N. Spergel et al., Laboratory limits on solar axions from an ultralow background germanium spectrometer, Phys. Rev. D 35, 2752 (1987).
  75. J. D. Bjorken, S. Ecklund, W. R. Nelson, A. Abashian, C. Church, B. Lu et al., Search for neutral metastable penetrating particles produced in the SLAC beam dump, Phys. Rev. D 38, 3375 (1988).
  76. LHCb Collaboration, Search for long-lived scalar particles in B+→K+χ(μ+μ−) decays, Phys. Rev. D 95, 071101 (2017).
  77. LHCb Collaboration, Search for hidden-sector bosons in B0→K*0μ+μ− decays, Phys. Rev. Lett. 115, 161802 (2015).
  78. B. Döbrich, F. Ertas, F. Kahlhoefer, and T. Spadaro, Model-independent bounds on light pseudoscalars from rare B-meson decays, Phys. Lett. B 790, 537 (2019).
  79. NA62 Collaboration, Measurement of the very rare K+→π+νν¯ decay, J. High Energy Phys. 06 (2021) 093.
  80. NA48/2 Collaboration, Precise measurement of the K±→π±e+e− decay, Phys. Lett. B 677, 246 (2009).
  81. NA48/2 Collaboration, Searches for lepton number violation and resonances in K±→πμμ decays, Phys. Lett. B 769, 67 (2017).
  82. A. Mariotti, D. Redigolo, F. Sala, and K. Tobioka, New LHC bound on low-mass diphoton resonances, Phys. Lett. B 783, 13 (2018).
  83. ATLAS Collaboration, Search for boosted diphoton resonances in the 10 to 70 GeV mass range using 138  fb−1 of 13 TeV pp collisions with the ATLAS detector, J. High Energy Phys. 07 (2023) 155.
  84. CMS Collaboration, Search for a scalar or pseudoscalar dilepton resonance produced in association with a massive vector boson or top quark-antiquark pair in multilepton events at s=13  TeV, Phys. Rev. D 110, 012013 (2024).
  85. ATLAS Collaboration, A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery, Nature (London) 607, 52 (2022).
  86. CMS Collaboration, First measurement of the cross section for top quark pair production with additional charm jets using dileptonic final states in pp collisions at s=13  TeV, Phys. Lett. B 820, 136565 (2021).
  87. CMS, ATLAS Collaboration, tt+X measurements by CMS and ATLAS, in Proceedings of the 12th International Workshop on the CKM Unitarity Triangle (2024), arXiv:2404.12046.
  88. CMS Collaboration, Evidence for four-top quark production in proton-proton collisions at s=13  TeV, Phys. Lett. B 844, 138076 (2023).
  89. ATLAS Collaboration, Measurements of top-quark pair differential and double-differential cross-sections in the ℓ+jets channel with pp collisions at s=13  TeV using the ATLAS detector, Eur. Phys. J. C 79, 1028 (2019).
  90. 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, 2250 (2014).
  91. T. Hahn, Generating Feynman diagrams and amplitudes with feynarts 3, Comput. Phys. Commun. 140, 418 (2001).
  92. T. Hahn and M. Perez-Victoria, Automatized one loop calculations in four-dimensions and D-dimensions, Comput. Phys. Commun. 118, 153 (1999).
  93. S. Blasi, F. Maltoni, A. Mariotti, K. Mimasu, D. Pagani, and S. Tentori, Top-philic ALP phenomenology at the LHC: The elusive mass-window, J. High Energy Phys. 06 (2024) 077.
  94. F. Maltoni, D. Pagani, and S. Tentori, Top-quark pair production as a probe of light top-philic scalars and anomalous Higgs interactions, J. High Energy Phys. 09 (2024) 098.
  95. F. Esser, M. Madigan, V. Sanz, and M. Ubiali, On the coupling of axion-like particles to the top quark, J. High Energy Phys. 09 (2023) 063.

Outline

Information

Phys. Rev. D 112, 055042– Published 29 September, 2025
  • Received 19 May 2025
  • Accepted 3 September 2025
Crossmark - Check for updates button
Creative Commons Logo

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation