- 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

Disentangling new physics with quantum entanglement in tt¯ production at future lepton colliders

Masato Arai1,*, Kentarou Mawatari2,3,4,†, and Nobuchika Okada5,‡

  • *Contact author: arai@sci.kj.yamagata-u.ac.jp
  • †Contact author: mawatari@iwate-u.ac.jp
  • ‡Contact author: okadan@ua.edu
PDF

Phys. Rev. D 114, 056001 – Published 1 September, 2026

DOI: https://doi.org/10.1103/9yfq-wtfn

Abstract

We investigate quantum entanglement and Bell-inequality violation in top-antitop pair production at future lepton colliders such as the International Linear Collider and multi-TeV muon colliders. Within the Standard Model (SM), the process proceeds through s-channel γ and Z exchange and exhibits characteristic spin-correlation patterns that encode a nontrivial amount of entanglement. We then examine how these features are modified in several well-motivated extensions of the SM; (i) a neutral scalar mediator that couples to charged leptons and top quarks via Yukawa interactions and contributes as an additional s-channel exchange, (ii) the minimal gauged U(1)B−L model, which introduces a new neutral gauge boson Z′ coupling vectorially to SM fermions, and (iii) a Randall-Sundrum scenario, in which the exchange of massive Kaluza-Klein gravitons arising from a warped extra dimension induces additional spin-dependent interactions. For all cases, we evaluate quantum-information observables including the entanglement marker, the concurrence, and the maximal Clauser-Horne-Shimony-Holt parameter, and study their dependence on the center-of-mass energy, scattering angle, and model parameters. We find that, relative to the SM expectation, the entanglement is typically reduced in the scalar-mediator scenario, while sizable deviations can arise in the U(1)B−L and Randall-Sundrum cases for phenomenologically relevant regions of parameter space. These results demonstrate the potential of quantum-information observables as sensitive probes of new particles and their interaction patterns in future lepton colliders.

View figure in article

Physics Subject Headings (PhySH)

Article Text

References (63)

  1. J. S. Bell, Phys. Phys. Fiz. 1, 195 (1964).
  2. A. Aspect, P. Grangier, and G. Roger, Phys. Rev. Lett. 49, 91 (1982).
  3. I. Bloch, J. Dalibard, and S. Nascimbène, Nat. Phys. 8, 267 (2012).
  4. G. L. Kane, G. A. Ladinsky, and C. P. Yuan, Phys. Rev. D 45, 124 (1992).
  5. W. Bernreuther and A. Brandenburg, Phys. Rev. D 49, 4481 (1994).
  6. S. J. Parke and Y. Shadmi, Phys. Lett. B 387, 199 (1996).
  7. W. Bernreuther, M. Flesch, and P. Haberl, Phys. Rev. D 58, 114031 (1998).
  8. W. Bernreuther, A. Brandenburg, Z. G. Si, and P. Uwer, Nucl. Phys. B690, 81 (2004).
  9. P. Uwer, Phys. Lett. B 609, 271 (2005).
  10. M. Baumgart and B. Tweedie, J. High Energy Phys. 03 (2013) 117.
  11. W. Bernreuther, D. Heisler, and Z. G. Si, J. High Energy Phys. 12 (2015) 026.
  12. T. Aaltonen et al. (CDF Collaboration), Phys. Rev. D 83, 031104 (2011).
  13. V. M. Abazov et al. (D0 Collaboration), Phys. Rev. Lett. 107, 032001 (2011).
  14. V. M. Abazov et al. (D0 Collaboration), Phys. Lett. B 757, 199 (2016).
  15. G. Aad et al. (ATLAS Collaboration), Phys. Rev. Lett. 108, 212001 (2012).
  16. S. Chatrchyan et al. (CMS Collaboration), Phys. Rev. Lett. 112, 182001 (2014).
  17. G. Aad et al. (ATLAS Collaboration), Phys. Rev. Lett. 114, 142001 (2015).
  18. A. M. Sirunyan et al. (CMS Collaboration), Phys. Rev. D 100, 072002 (2019).
  19. M. Aaboud et al. (ATLAS Collaboration), Eur. Phys. J. C 80, 754 (2020).
  20. Y. Afik and J. R. M. de Nova, Eur. Phys. J. Plus 136, 907 (2021).
  21. M. Fabbrichesi, R. Floreanini, and G. Panizzo, Phys. Rev. Lett. 127, 161801 (2021).
  22. C. Severi, C. D. Boschi, F. Maltoni, and M. Sioli, Eur. Phys. J. C 82, 285 (2022).
  23. Y. Afik and J. R. M. de Nova, Quantum 6, 820 (2022).
  24. J. A. Aguilar-Saavedra and J. A. Casas, Eur. Phys. J. C 82, 666 (2022).
  25. F. Maltoni, C. Severi, S. Tentori, and E. Vryonidou, J. High Energy Phys. 03 (2024) 099.
  26. A. J. Barr, Phys. Lett. B 825, 136866 (2022).
  27. M. Fabbrichesi, R. Floreanini, E. Gabrielli, and L. Marzola, Eur. Phys. J. C 83, 823 (2023).
  28. G. Aad et al. (ATLAS Collaboration), Nature (London) 633, 542 (2024).
  29. A. Hayrapetyan et al. (CMS Collaboration), Phys. Rev. D 110, 112016 (2024).
  30. F. Maltoni, C. Severi, S. Tentori, and E. Vryonidou, J. High Energy Phys. 09 (2024) 001.
  31. K. Ehatäht, M. Fabbrichesi, L. Marzola, and C. Veelken, Phys. Rev. D 109, 032005 (2024).
  32. T. Han, M. Low, and Y. Su, J. High Energy Phys. 10 (2025) 217.
  33. B. Yang, Y. Zhang, Z. S. Wang, and X. Zhou, arXiv:2603.05846.
  34. P. Lo Chiatto, Phys. Rev. D 112, 015017 (2025).
  35. K. Cheng, T. Han, and M. Low, Phys. Lett. B 868, 139675 (2025).
  36. V. Durupt, F. Maltoni, and O. Mattelaer, J. High Energy Phys. 04 (2026) 103.
  37. M. M. Altakach, P. Lamba, F. Maltoni, and K. Sakurai, J. High Energy Phys. 07 (2026) 091.
  38. K. Cheng, T. Han, and M. Low, Phys. Rev. D 111, 033004 (2025).
  39. H. W. Zhang, X. Cao, and T. F. Feng, Phys. Rev. D 113, 114022 (2026).
  40. Y. C. Guo, T. Han, M. Low, and Y. Su, arXiv:2602.02719.
  41. T. Han, M. Low, N. McGinnis, and S. Su, J. High Energy Phys. 05 (2025) 081.
  42. L. Antozzi, E. Chalbaud, F. Déliot, F. Fabbri, M. C. N. Fiolhais, B. Fuks, A. Onofre, M. White, and P. Zhu, J. High Energy Phys. 06 (2026) 139.
  43. M. Duch, A. Strumia, and A. Titov, Eur. Phys. J. C 85, 151 (2025).
  44. R. N. Mohapatra and R. E. Marshak, Phys. Rev. Lett. 44, 1316 (1980); 44, 1643(E) (1980).
  45. R. E. Marshak and R. N. Mohapatra, Phys. Lett. 91B, 222 (1980).
  46. C. Wetterich, Nucl. Phys. B187, 343 (1981).
  47. A. Masiero, J. F. Nieves, and T. Yanagida, Phys. Lett. 116B, 11 (1982).
  48. R. N. Mohapatra and G. Senjanovic, Phys. Rev. D 27, 254 (1983).
  49. W. Buchmuller, C. Greub, and P. Minkowski, Phys. Lett. B 267, 395 (1991).
  50. L. Randall and R. Sundrum, Phys. Rev. Lett. 83, 3370 (1999).
  51. W. K. Wootters, Phys. Rev. Lett. 80, 2245 (1998).
  52. J. F. Clauser, M. A. Horne, A. Shimony, and R. A. Holt, Phys. Rev. Lett. 23, 880 (1969).
  53. J. S. Bell, Rev. Mod. Phys. 38, 447 (1966).
  54. B. S. Cirelson, Lett. Math. Phys. 4, 93 (1980).
  55. R. Horodecki, P. Horodecki, and M. Horodecki, Phys. Lett. A 200, 340 (1995).
  56. A. Davidson, Phys. Rev. D 20, 776 (1979).
  57. H. Davoudiasl, J. L. Hewett, and T. G. Rizzo, Phys. Rev. Lett. 84, 2080 (2000).
  58. H. Davoudiasl, J. L. Hewett, and T. G. Rizzo, Phys. Rev. D 63, 075004 (2001).
  59. H. Murayama, I. Watanabe, and K. Hagiwara, HELAS: HELicity amplitude subroutines for Feynman diagram evaluations, KEK Report No. KEK-91-11, 1992.
  60. J. Alwall, R. Frederix, S. Frixione, V. Hirschi, F. Maltoni, O. Mattelaer, H. S. Shao, T. Stelzer, P. Torrielli, and M. Zaro, J. High Energy Phys. 07 (2014) 079.
  61. P. Artoisenet, P. de Aquino, F. Demartin, R. Frederix, S. Frixione, F. Maltoni, M. K. Mandal, P. Mathews, K. Mawatari, V. Ravindran et al., J. High Energy Phys. 11 (2013) 043.
  62. A. Das, P. S. B. Dev, Y. Hosotani, and S. Mandal, Phys. Rev. D 105, 115030 (2022).
  63. Y. J. Fang, A. Bhoonah, K. Cheng, T. Han, Y. Liu, and H. Zhang, arXiv:2604.11887.

Outline

Information

Phys. Rev. D 114, 056001– Published 1 September, 2026
  • Received 4 May 2026
  • Accepted 14 August 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