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γZ-exchange contribution in elastic ep scattering by perturbative QCD

Qian-Qian Guo1,2,*, Hui-Yun Cao3, and Hai-Qing Zhou2,†

  • *Contact author: guoqq@lit.edu.cn
  • †Contact author: zhouhq@seu.edu.cn
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Phys. Rev. C 114, 025204 – Published 14 August, 2026

DOI: https://doi.org/10.1103/8j1r-3yxl

Abstract

In this study, we calculate the γZ-exchange contribution to elastic ep scattering at large momentum transfer within perturbative quantum chromodynamics (pQCD). We present analytical expressions for the γZ-exchange contributions to the amplitudes. We also estimate the asymptotic behaviors of the amplitude contributions and of the physical quantity APV at high momentum transfer. These asymptotic behaviors determine the subtraction order in the dispersion relations (DRs) satisfied by the amplitudes. At high Q2 beyond the forward limit, our pQCD analysis shows that this subtraction order is fixed by the high-ν behavior of the amplitude coefficients ciγZ,PV, and that c3,AγZ,PV requires a once-subtracted DR. Within the present pQCD framework and the adopted proton distribution amplitudes, these high-energy results also provide nontrivial constraints on low-energy DR assumptions.

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Phys. Rev. C 114, 025204– Published 14 August, 2026
  • Received 24 April 2026
  • Revised 21 June 2026
  • Accepted 27 July 2026
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