- Physical Review Journals
All JournalsPhysics Magazine

Physical Review Letters

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

Unveiling Light-Quark Yukawa Flavor Structure via Dihadron Fragmentation at Lepton Colliders

Qing-Hong Cao1,2,3, Xin-Kai Wen4,5,*, Bin Yan4,3,†, and Shu-Tao Zhang1

  • *Contact author: xinkaiwen@ihep.ac.cn
  • †Contact author: yanbin@ihep.ac.cn
PDF

Phys. Rev. Lett. 136, 231901 – Published 9 June, 2026

DOI: https://doi.org/10.1103/p5c7-m43d

Abstract

Directly probing light-quark Yukawa couplings and their flavor structure remains a major challenge due to their smallness and overwhelming QCD backgrounds. In this Letter, we propose a theoretical framework to access these couplings at lepton colliders through transverse spin dependent azimuthal modulations in dihadron fragmentation. These modulations arise from the interference between Higgs mediated and standard model amplitudes in e−e+→qq¯Z, producing angular structures that are linearly sensitive to the Yukawa couplings yq, in contrast to conventional observables that scale as yq2. By combining channels with an identified accompanying single hadron, h′=π±,K±, and p/p¯, this approach cleanly disentangles the up- and down-quark Yukawa contributions, yielding typical limits at the O(10−4–10−3) level and establishing fragmentation dynamics as a novel and complementary probe of the Higgs flavor structure.

View figure in article

Physics Subject Headings (PhySH)

Article Text

References (79)

  1. Q.-H. Cao, S.-L. Chen, and Y. Liu, Phys. Rev. D 95, 053004 (2017).
  2. Q.-H. Cao, S.-L. Chen, Y. Liu, R. Zhang, and Y. Zhang, Phys. Rev. D 99, 113003 (2019).
  3. G. Li, L.-X. Xu, B. Yan, and C. P. Yuan, Phys. Lett. B 800, 135070 (2020).
  4. Q.-H. Cao, K.-P. Xie, H. Zhang, and R. Zhang, Chin. Phys. C 45, 023117 (2021).
  5. Q. Bi, K. Chai, J. Gao, Y. Liu, and H. Zhang, Chin. Phys. C 45, 023105 (2021).
  6. G. Aad et al. (ATLAS Collaboration), Nature (London) 607, 52 (2022); 612, E24(E) (2022).
  7. A. Tumasyan et al. (CMS Collaboration), Nature (London) 607, 60 (2022); 623, E4(E) (2023).
  8. A. Tumasyan et al. (CMS Collaboration), Eur. Phys. J. C 83, 562 (2023).
  9. G. Aad et al. (ATLAS Collaboration), arXiv:2510.23755.
  10. G. Aad et al. (ATLAS Collaboration), J. High Energy Phys. 03 (2025) 010.
  11. G. Aad et al. (ATLAS Collaboration), J. High Energy Phys. 04 (2025) 075.
  12. G. T. Bodwin, F. Petriello, S. Stoynev, and M. Velasco, Phys. Rev. D 88, 053003 (2013).
  13. A. L. Kagan, G. Perez, F. Petriello, Y. Soreq, S. Stoynev, and J. Zupan, Phys. Rev. Lett. 114, 101802 (2015).
  14. M. König and M. Neubert, J. High Energy Phys. 08 (2015) 012.
  15. I. Brivio, F. Goertz, and G. Isidori, Phys. Rev. Lett. 115, 211801 (2015).
  16. G. Aad et al. (ATLAS Collaboration), J. High Energy Phys. 02 (2025) 045.
  17. A. Hayrapetyan et al. (CMS Collaboration), arXiv:2508.14988.
  18. G. Aad et al. (ATLAS Collaboration), Phys. Rev. Lett. 135, 231802 (2025).
  19. A. Hayrapetyan et al. (CMS Collaboration), Phys. Rev. Lett. 132, 121901 (2024).
  20. V. Chekhovsky et al. (CMS Collaboration), Phys. Rev. D 112, 112001 (2025).
  21. S. Bar-Shalom and A. Soni, Phys. Rev. D 98, 055001 (2018).
  22. B. A. Erdelyi, R. Gröber, and N. Selimovic, J. High Energy Phys. 05 (2025) 189.
  23. Y. Zhou, Phys. Rev. D 93, 013019 (2016).
  24. F. Bishara, U. Haisch, P. F. Monni, and E. Re, Phys. Rev. Lett. 118, 121801 (2017).
  25. Y. Soreq, H. X. Zhu, and J. Zupan, J. High Energy Phys. 12 (2016) 045.
  26. J. Gao, J. High Energy Phys. 01 (2018) 038.
  27. F. Yu, J. High Energy Phys. 02 (2017) 083.
  28. A. Falkowski, S. Ganguly, P. Gras, J. M. No, K. Tobioka, N. Vignaroli, and T. You, J. High Energy Phys. 04 (2021) 023.
  29. N. Vignaroli, Symmetry 14, 1183 (2022).
  30. L. Alasfar, R. Gröber, C. Grojean, A. Paul, and Z. Qian, J. High Energy Phys. 11 (2022) 045.
  31. E. Balzani, R. Gröber, and M. Vitti, J. High Energy Phys. 10 (2023) 027.
  32. B. Yan and C. Lee, J. High Energy Phys. 03 (2024) 123.
  33. J. K. L. Michel, arXiv:2508.05914.
  34. J. de Blas et al., J. High Energy Phys. 01 (2020) 139.
  35. J. C. Collins, S. F. Heppelmann, and G. A. Ladinsky, Nucl. Phys. B420, 565 (1994).
  36. J. Collins, Foundations of Perturbative QCD (Cambridge University Press, Cambridge, England, 2011), Vol. 32, ISBN [Amazon][WorldCat], [Amazon][WorldCat], [Amazon][WorldCat].
  37. J. Zhou and A. Metz, Phys. Rev. Lett. 106, 172001 (2011).
  38. R. Boughezal, D. de Florian, F. Petriello, and W. Vogelsang, Phys. Rev. D 107, 075028 (2023).
  39. H.-L. Wang, X.-K. Wen, H. Xing, and B. Yan, Phys. Rev. D 109, 095025 (2024).
  40. X.-K. Wen, B. Yan, Z. Yu, and C. P. Yuan, arXiv:2408.07255.
  41. X.-K. Wen, B. Yan, Z. Yu, and C. P. Yuan, Phys. Rev. D 112, 053004 (2025).
  42. L. Yang, Y.-K. Song, and S.-Y. Wei, Phys. Rev. D 111, 054035 (2025).
  43. K. Cheng and B. Yan, Phys. Rev. Lett. 135, 011902 (2025).
  44. Y. Huang, X.-B. Tong, and H.-L. Wang, Phys. Rev. Lett. 136, 131902 (2026).
  45. Q.-H. Cao, G. Li, X.-K. Wen, and B. Yan, arXiv:2509.18276.
  46. X.-y. Qin, Y.-K. Song, and S.-y. Wei, Phys. Rev. D 113, 014007 (2026).
  47. Z.-G. He, G. Li, Y.-J. Tian, X.-K. Wen, and B. Yan, arXiv:2603.18874.
  48. X.-K. Wen, B. Yan, and S. Zhang (in preparation).
  49. Z. Yu, Ph.D. thesis, 2023, arXiv:2308.13080.
  50. S. M. Berman, J. D. Bjorken, and J. B. Kogut, Phys. Rev. D 4, 3388 (1971).
  51. R. D. Field and R. P. Feynman, Nucl. Phys. B136, 1 (1978).
  52. R. P. Feynman, R. D. Field, and G. C. Fox, Phys. Rev. D 18, 3320 (1978).
  53. X. Ai et al., Chin. Phys. C 49, 123108 (2025).
  54. M. Dong et al. (CEPC Study Group), arXiv:1811.10545.
  55. W. Abdallah et al. (CEPC Study Group), Radiat. Detect. Technol. Methods 8, 1 (2024); 9, 184 (2025).
  56. Howard Baer et al., arXiv:1306.6352.
  57. A. Abada et al. (FCC Collaboration), Eur. Phys. J. Special Topics 228, 261 (2019).
  58. D. Pitonyak, C. Cocuzza, A. Metz, A. Prokudin, and N. Sato, Phys. Rev. Lett. 132, 011902 (2024).
  59. C. Cocuzza, A. Metz, D. Pitonyak, A. Prokudin, N. Sato, and R. Seidl (JAM Collaboration), Phys. Rev. Lett. 132, 091901 (2024).
  60. C. Cocuzza, A. Metz, D. Pitonyak, A. Prokudin, N. Sato, and R. Seidl (Jefferson Lab Angular Momentum (JAM) Collaboration), Phys. Rev. D 109, 034024 (2024).

  61. Higher-order QCD corrections are not expected to qualitatively alter our conclusions, analogous to the cancellation effects observed in spin asymmetry ratios in polarized Drell-Yan [62] and SIDIS [63, 64].

  62. D. de Florian, Phys. Rev. D 96, 094006 (2017).
  63. D. Rein, M. Schlegel, P. Tollkühn, and W. Vogelsang, Phys. Rev. Lett. 135, 251901 (2025).
  64. D. Rein, M. Schlegel, P. Tollkühn, and W. Vogelsang, Phys. Rev. D 112, 114024 (2025).
  65. A. Courtoy, A. Bacchetta, M. Radici, and A. Bianconi, Phys. Rev. D 85, 114023 (2012).
  66. M. Radici, A. Courtoy, A. Bacchetta, and M. Guagnelli, J. High Energy Phys. 05 (2015) 123.
  67. N. Sato, J. J. Ethier, W. Melnitchouk, M. Hirai, S. Kumano, and A. Accardi, Phys. Rev. D 94, 114004 (2016).
  68. V. Bertone, S. Carrazza, N. P. Hartland, E. R. Nocera, and J. Rojo (NNPDF Collaboration), Eur. Phys. J. C 77, 516 (2017).
  69. N. Sato, C. Andres, J. J. Ethier, and W. Melnitchouk (JAM Collaboration), Phys. Rev. D 101, 074020 (2020).
  70. E. Moffat, W. Melnitchouk, T. C. Rogers, and N. Sato (Jefferson Lab Angular Momentum (JAM) Collaboration), Phys. Rev. D 104, 016015 (2021).
  71. C. Cocuzza, W. Melnitchouk, A. Metz, and N. Sato (Jefferson Lab Angular Momentum (JAM) Collaboration), Phys. Rev. D 106, L031502 (2022).
  72. J. Gao, C. Liu, X. Shen, H. Xing, and Y. Zhao, Phys. Rev. Lett. 132, 261903 (2024).
  73. J. Gao, C. Liu, X. Shen, H. Xing, and Y. Zhao, Phys. Rev. D 110, 114019 (2024).
  74. V. Mahaut, L. Polano, A. Bacchetta, V. Bertone, M. Cerutti, M. Radici, and L. Rossi, J. High Energy Phys. 02 (2026) 051.

  75. Different choices of DiFF (JAM [60] and MAP [65, 66, 74]) and single-hadron FF (JAM [70], NNFF [68], and NPC [72, 73]) parametrizations are expected to yield consistent conclusions in this Letter.

  76. B. Zhou and J. Gao, J. High Energy Phys. 02 (2025) 003.
  77. R. Aaij et al. (LHCb Collaboration), Eur. Phys. J. C 72, 2168 (2012).
  78. G. Soyez, Phys. Rep. 803, 1 (2019).
  79. R. Aaij et al. (LHCb Collaboration), arXiv:1808.08865.

Outline

Information

Phys. Rev. Lett. 136, 231901– Published 9 June, 2026
  • Received 2 January 2026
  • Revised 18 April 2026
  • Accepted 14 May 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