- 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

Didecay signature of new physics particles at intensity frontier experiments

Giovani Dalla Valle Garcia1,* and Maksym Ovchynnikov2,†

  • *Contact author: giovani.garcia@student.kit.edu
  • †Contact author: maksym.ovchynnikov@cern.ch
PDF

Phys. Rev. D 114, 035012 – Published 5 August, 2026

DOI: https://doi.org/10.1103/l1t6-5nyh

Abstract

We present a discovery-era strategy for intensity frontier experiments based on “didecay” events, in which feebly interacting particles (FIPs) are produced in pairs and then both decay inside the detector. This signature may exist in broad classes of models with FIPs decaying in the same way as minimal “portal” particles. The two displaced vertices may allow reconstruction of the pair invariant mass and hence reveal the production channel, information normally inaccessible at these facilities. This, in turn, lets one discriminate between FIP models that share identical decay signatures. As a case study, we consider the model of Higgs-like scalars and show that SHiP, Belle II, and the Downstream@LHCb can each cover wide domains of viable parameter space using didecays.

View figure in article

Physics Subject Headings (PhySH)

Article Text

References (98)

  1. S. Alekhin et al., A facility to search for hidden particles at the CERN SPS: The SHiP physics case, Rep. Prog. Phys. 79, 124201 (2016).
  2. J. Beacham et al., Physics beyond colliders at CERN: Beyond the standard model working group report, J. Phys. G 47, 010501 (2020).
  3. C. Antel et al., Feebly interacting particles: FIPs 2022 workshop report, Eur. Phys. J. C 83, 1122 (2023).
  4. T. Asaka and M. Shaposhnikov, The νMSM, dark matter and baryon asymmetry of the universe, Phys. Lett. B 620, 17 (2005).
  5. M. Bauer, M. Neubert, and A. Thamm, Collider probes of axion-like particles, J. High Energy Phys. 12 (2017) 044.
  6. D. Aloni, Y. Soreq, and M. Williams, Coupling QCD-scale axionlike particles to gluons, Phys. Rev. Lett. 123, 031803 (2019).
  7. 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.
  8. M. Bauer, M. Neubert, S. Renner, M. Schnubel, and A. Thamm, Flavor probes of axion-like particles, J. High Energy Phys. 09 (2022) 056.
  9. G. Dalla Valle Garcia, F. Kahlhoefer, M. Ovchynnikov, and A. Zaporozhchenko, Phenomenology of axionlike particles with universal fermion couplings revisited, Phys. Rev. D 109, 055042 (2024).
  10. M. Ovchynnikov and A. Zaporozhchenko, ALPs coupled to gluons in the GeV mass range—data-driven and consistent, Phys. Rev. D 112, 015001 (2025).
  11. P. Ilten, Y. Soreq, M. Williams, and W. Xue, Serendipity in dark photon searches, J. High Energy Phys. 06 (2018) 004.
  12. Y. Kyselov and M. Ovchynnikov, Searches for long-lived dark photons at proton accelerator experiments, Phys. Rev. D 111, 015030 (2025).
  13. I. Boiarska, K. Bondarenko, A. Boyarsky, V. Gorkavenko, M. Ovchynnikov, and A. Sokolenko, Phenomenology of GeV-scale scalar portal, J. High Energy Phys. 11 (2019) 162.
  14. T. Ferber, A. Grohsjean, and F. Kahlhoefer, Dark Higgs bosons at colliders, Prog. Part. Nucl. Phys. 136, 104105 (2024).
  15. K. Bondarenko, A. Boyarsky, D. Gorbunov, and O. Ruchayskiy, Phenomenology of GeV-scale heavy neutral leptons, J. High Energy Phys. 11 (2018) 032.
  16. Y.-D. Tsai, P. deNiverville, and M. X. Liu, Dark Photon and Muon g−2 Inspired Inelastic Dark Matter Models at the High-Energy Intensity Frontier, Phys. Rev. Lett. 126, 181801 (2021).
  17. W. Altmannshofer et al. (Belle-II Collaboration), The Belle II physics book, Prog. Theor. Exp. Phys. 2019, 123C01 (2019); 2020, 029201(E) (2020).
  18. E. Cortina Gil et al. (NA62 Collaboration), Search for dark photon decays to μ+μ− at NA62, J. High Energy Phys. 09 (2023) 035.
  19. A. Ariga et al. (FASER Collaboration), FASER: ForwArd search ExpeRiment at the LHC, arXiv:1901.04468.
  20. G. Acampora et al. (SND@LHC Collaboration), SND@LHC: The scattering and neutrino detector at the LHC, J. Instrum. 19, P05067 (2024).
  21. O. Aberle et al. (SHiP Collaboration), BDF/SHiP at the ECN3 high-intensity beam facility, Technical report, CERN, Geneva, 2022, http://cds.cern.ch/record/2839677.
  22. B. Acharya et al. (MoEDAL-MAPP Collaboration), MoEDAL-MAPP, an LHC dedicated detector search facility, in Snowmass 2021 (2022), 9; arXiv:2209.03988.
  23. A. Apyan et al., DarkQuest: A dark sector upgrade to SpinQuest at the 120 GeV fermilab main injector, in Snowmass 2021 (2022), 3, 2022; arXiv:2203.08322.
  24. B. Abi et al. (DUNE Collaboration), Deep Underground Neutrino Experiment (DUNE), far detector technical design report, Volume I Introduction to DUNE, J. Instrum. 15, T08008 (2020).
  25. V. Gorkavenko, B. K. Jashal, V. Kholoimov, Y. Kyselov, D. Mendoza, M. Ovchynnikov, A. Oyanguren, V. Svintozelskyi, and J. Zhuo, LHCb potential to discover long-lived new physics particles with lifetimes above 100 ps, Eur. Phys. J. C 84, 608 (2024).
  26. V. Kholoimov, B. K. Jashal, A. Oyanguren, V. Svintozelskyi, and J. Zhuo, A downstream and vertexing algorithm for long lived particles (LLP) selection at the first high-level trigger (HLT1) of LHCb, Comput. Software Big Sci. 9, 10 (2025).
  27. M. Bauer, O. Brandt, L. Lee, and C. Ohm, ANUBIS: Proposal to search for long-lived neutral particles in CERN service shafts, arXiv:1909.13022.
  28. C. Alpigiani et al. (MATHUSLA Collaboration), Recent progress and next steps for the MATHUSLA LLP detector, in 2022 Snowmass Summer Study (2022), 3, 2022; arXiv:2203.08126.
  29. G. Aielli et al., Expression of interest for the CODEX-b detector, Eur. Phys. J. C 80, 1177 (2020).
  30. J. Niedziela, SHIFT@LHC: Searches for new physics with shifted interaction on a fixed target at the large hadron collider, J. High Energy Phys. 10 (2020) 204.
  31. J. L. Feng et al., The forward physics facility at the high-luminosity LHC, J. Phys. G 50, 030501 (2023).
  32. B. Hacisahinoglu, S. Ozkorucuklu, M. Ovchynnikov, M. G. Albrow, O. Aydilek, and A. Penzo, PREFACE: A search for long-lived particles at the large hadron collider, MDPI Phys. 7, 33 (2025).
  33. J.-L. Tastet, O. Ruchayskiy, and I. Timiryasov, Reinterpreting the ATLAS bounds on heavy neutral leptons in a realistic neutrino oscillation model, J. High Energy Phys. 12 (2021) 182.
  34. O. Mikulenko, K. Bondarenko, A. Boyarsky, and O. Ruchayskiy, New physics at the intensity frontier: How much can we learn and how?, arXiv:2312.00659.
  35. O. Mikulenko, K. Bondarenko, A. Boyarsky, and O. Ruchayskiy, Unveiling new physics with discoveries at intensity frontier, arXiv:2312.05163.
  36. K. Chathirathas, T. Ferber, F. Kahlhoefer, and A. Morandini, Finding excesses in model parameter space, Eur. Phys. J. C 85, 149 (2025).
  37. O. Mikulenko, Quasi-Dirac heavy neutral leptons in the left-right symmetric model, J. High Energy Phys. 06 (2025) 023.
  38. Q.-H. Cao, K. Cheng, and Y. Liu, Distinguishing Dirac from Majorana heavy neutrino at future lepton colliders, Phys. Rev. Lett. 134, 021801 (2025).
  39. A. Monin, A. Boyarsky, and O. Ruchayskiy, Hadronic decays of a light Higgs-like scalar, Phys. Rev. D 99, 015019 (2019).
  40. P. J. Blackstone, J. Tarrús Castellà, E. Passemar, and J. Zupan, Hadronic decays of a Higgs-mixed scalar, arXiv:2407.13587.
  41. S. Chatrchyan et al. (CMS Collaboration), Search for a non-standard-model Higgs boson decaying to a pair of new light bosons in four-muon final states, Phys. Lett. B 726, 564 (2013).
  42. D. Curtin et al., Exotic decays of the 125 GeV Higgs boson, Phys. Rev. D 90, 075004 (2014).
  43. X. Cid Vidal, Y. Tsai, and J. Zurita, Exclusive displaced hadronic signatures in the LHC forward region, J. High Energy Phys. 01 (2020) 115.
  44. G. Aad et al. (ATLAS Collaboration), Search for light long-lived neutral particles that decay to collimated pairs of leptons or light hadrons in pp collisions at s=13  TeV with the ATLAS detector, J. High Energy Phys. 06 (2023) 153.
  45. G. Aad et al. (ATLAS Collaboration), Search for short- and long-lived axion-like particles in H→aa→4γ decays with the ATLAS experiment at the LHC, Eur. Phys. J. C 84, 742 (2024).
  46. A. Hayrapetyan et al. (CMS Collaboration), Model-independent search for pair production of new bosons decaying into muons in proton-proton collisions at s=13  TeV, J. High Energy Phys. 12 (2024) 172.
  47. A. Hayrapetyan et al. (CMS Collaboration), Search for new resonances decaying to pairs of merged diphotons in proton-proton collisions at s=13  TeV, Phys. Rev. Lett. 134, 041801 (2025).
  48. A. Hayrapetyan et al. (CMS Collaboration), Search for the decay of the Higgs boson to a pair of light pseudoscalar bosons in the final state with four bottom quarks in proton-proton collisions at s=13  TeV, J. High Energy Phys. 06 (2024) 097.
  49. M. Acevedo, A. Blackburn, N. Blinov, B. Shuve, and M. Stone, Multi-track displaced vertices at B-factories, J. High Energy Phys. 09 (2021) 154.
  50. E. Bernreuther, N. Hemme, F. Kahlhoefer, S. Kulkarni, and M. Ovchynnikov, Sub-GeV dark matter and multi-decay signatures from dark showers at beam-dump experiments, Phys. Rev. D 113, 075002 (2026).
  51. G. Dalla Valle Garcia, F. Kahlhoefer, t. Schwetz, and M. Ovchynnikov, Multiparticle signatures from inelastic dark matter at colliders (to be published).
  52. I. Boiarska, K. Bondarenko, A. Boyarsky, M. Ovchynnikov, O. Ruchayskiy, and A. Sokolenko, Light scalar production from Higgs bosons and FASER 2, J. High Energy Phys. 05 (2020) 049.
  53. D. Curtin and J. S. Grewal, Long lived particle decays in MATHUSLA, Phys. Rev. D 109, 075017 (2024).
  54. M. L. Graesser, Broadening the Higgs boson with right-handed neutrinos and a higher dimension operator at the electroweak scale, Phys. Rev. D 76, 075006 (2007).
  55. M. L. Graesser, Experimental constraints on Higgs boson decays to TeV-scale right-handed neutrinos, arXiv:0705.2190.
  56. A. Caputo, P. Hernandez, J. Lopez-Pavon, and J. Salvado, The seesaw portal in testable models of neutrino masses, J. High Energy Phys. 06 (2017) 112.
  57. J. M. Butterworth, M. Chala, C. Englert, M. Spannowsky, and A. Titov, Higgs phenomenology as a probe of sterile neutrinos, Phys. Rev. D 100, 115019 (2019).
  58. D. Barducci, E. Bertuzzo, A. Caputo, P. Hernandez, and B. Mele, The See-saw portal at future Higgs factories, J. High Energy Phys. 03 (2021) 117.
  59. M. Bauer, G. Rostagni, and J. Spinner, Axion-Higgs portal, Phys. Rev. D 107, 015007 (2023).
  60. F. Deppisch, S. Kulkarni, and W. Liu, Heavy neutrino production via Z′ at the lifetime frontier, Phys. Rev. D 100, 035005 (2019).
  61. A. M. Abdullahi et al., The present and future status of heavy neutral leptons, J. Phys. G 50, 020501 (2023).
  62. A. Berlin and F. Kling, Inelastic dark matter at the LHC lifetime frontier: ATLAS, CMS, LHCb, CODEX-b, FASER, and MATHUSLA, Phys. Rev. D 99, 015021 (2019).
  63. P. Schwaller, D. Stolarski, and A. Weiler, Emerging jets, J. High Energy Phys. 05 (2015) 059.
  64. G. D. Kribs and E. T. Neil, Review of strongly-coupled composite dark matter models and lattice simulations, Int. J. Mod. Phys. A 31, 1643004 (2016).
  65. E. Bernreuther, F. Kahlhoefer, M. Krämer, and P. Tunney, Strongly interacting dark sectors in the early universe and at the LHC through a simplified portal, J. High Energy Phys. 01 (2020) 162.
  66. G. Albouy et al., Theory, phenomenology, and experimental avenues for dark showers: A snowmass 2021 report, Eur. Phys. J. C 82, 1132 (2022).
  67. H.-C. Cheng, L. Li, and E. Salvioni, A theory of dark pions, J. High Energy Phys. 01 (2022) 122.
  68. H.-C. Cheng, X.-H. Jiang, L. Li, and E. Salvioni, Dark showers from Z-dark Z’ mixing, J. High Energy Phys. 04 (2024) 081.
  69. F. Bezrukov and D. Gorbunov, Light inflaton hunter’s guide, J. High Energy Phys. 05 (2010) 010.
  70. G. Krnjaic, Probing light thermal dark-matter with a Higgs portal mediator, Phys. Rev. D 94, 073009 (2016).
  71. C. Bierlich et al., A comprehensive guide to the physics and usage of pythia8.3, SciPost Phys. Codebases 2022, 8 (2022).
  72. K. Bondarenko, A. Boyarsky, M. Ovchynnikov, and O. Ruchayskiy, Sensitivity of the intensity frontier experiments for neutrino and scalar portals: Analytic estimates, J. High Energy Phys. 08 (2019) 061.
  73. M. Anelli et al. (SHiP Collaboration), A facility to search for hidden particles (SHiP) at the CERN SPS, arXiv:1504.04956.
  74. A. Ariga et al. (FASER Collaboration), Technical proposal for FASER: ForwArd search ExpeRiment at the LHC, arXiv:1812.09139.
  75. A. Blondel et al., Searches for long-lived particles at the future FCC-ee, Front. Phys. 10, 967881 (2022).
  76. I. Adachi et al. (Belle-II Collaboration), Search for a long-lived spin-0 mediator in b→s transitions at the Belle II experiment, Phys. Rev. D 108, L111104 (2023).
  77. A. Fradette, M. Pospelov, J. Pradler, and A. Ritz, Cosmological beam dump: Constraints on dark scalars mixed with the Higgs boson, Phys. Rev. D 99, 075004 (2019).
  78. M. W. Winkler, Decay and detection of a light scalar boson mixing with the Higgs boson, Phys. Rev. D 99, 015018 (2019).
  79. R. e. a. Alemany Fernandez, Summary report of the physics beyond colliders study at CERN, Technical Report, CERN, Geneva, 2025, https://cds.cern.ch/record/2927631.
  80. R. Albanese et al. (SHiP, HI-ECN3 Project Team Collaborations), SHiP experiment at the SPS beam dump facility, arXiv:2504.06692.
  81. A. Tumasyan et al. (CMS Collaboration), A search for decays of the Higgs boson to invisible particles in events with a top-antitop quark pair or a vector boson in proton-proton collisions at s=13  TeV, Eur. Phys. J. C 83, 933 (2023).
  82. C. Bernaciak, T. Plehn, P. Schichtel, and J. Tattersall, Spying an invisible Higgs boson, Phys. Rev. D 91, 035024 (2015).
  83. P. Bechtle, S. Heinemeyer, O. Stål, T. Stefaniak, and G. Weiglein, Probing the standard model with Higgs signal rates from the tevatron, the LHC and a future ILC, J. High Energy Phys. 11 (2014) 039.
  84. F. Wilczek, Decays of heavy vector mesons into Higgs particles, Phys. Rev. Lett. 39, 1304 (1977).
  85. M. Ovchynnikov, J.-L. Tastet, O. Mikulenko, and K. Bondarenko, Sensitivities to feebly interacting particles: Public and unified calculations, Phys. Rev. D 108, 075028 (2023).
  86. M. Ovchynnikov, senscalc, Online at https://doi.org/10.5281/zenodo.7957784, 2023.
  87. L. Collaboration (LHCb Collaboration), Background study from BuSca: Insights from October 2024 LHCb data,. https://cds.cern.ch/record/2923556.
  88. LHCb Collaboration, BuSca: A buffer scanner at HLT1 using 2024 LHCb data,. https://cds.cern.ch/record/2914494.
  89. G. Dalla Valle Garcia, New directions in inelastic dark matter—the role of parity in dark sectors. PhD thesis, Karlsruhe Institute of Technology, 10, 2025.
  90. J. F. Donoghue, J. Gasser, and H. Leutwyler, The decay of a light Higgs boson, Nucl. Phys. B343, 341 (1990).
  91. M. Neubert, Heavy quark symmetry, Phys. Rep. 245, 259 (1994).
  92. H. Dijkstra and T. Ruf (SHiP Collaboration), Heavy Flavour Cascade Production in a Beam Dump, Online at https://cds.cern.ch/record/2115534 (2015), CERN-SHiP-NOTE-2015-009.
  93. G. D. V. Garcia, F. Kahlhoefer, M. Ovchynnikov, and T. Schwetz, Not-so-inelastic dark matter, J. High Energy Phys. 02 (2025) 127.
  94. M. Cepeda et al., Report from Working Group 2: Higgs physics at the HL-LHC and HE-LHC, CERN Yellow Rep. Monogr. 7, 221 (2019).
  95. R. Aaij et al. (LHCb Collaboration), LHCb detector performance, Int. J. Mod. Phys. A 30, 1530022 (2015).
  96. Y. T. Lai et al., Design of the global reconstruction logic in the Belle II level-1 trigger system, Nucl. Instrum. Methods Phys. Res., Sect. A 1078, 170577 (2025).
  97. S. Bähr et al., The neural network first-level hardware track trigger of the belle IIexperiment, Nucl. Instrum. Methods Phys. Res., Sect. A 1073, 170279 (2025).
  98. M. J. Dolan, F. Kahlhoefer, C. McCabe, and K. Schmidt-Hoberg, A taste of dark matter: Flavour constraints on pseudoscalar mediators, J. High Energy Phys. 03 (2015) 171; 07 (2015) 103(E).

Outline

Information

Phys. Rev. D 114, 035012– Published 5 August, 2026
  • Received 5 March 2025
  • Revised 15 July 2025
  • Accepted 15 July 2026
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