https://doi.org/10.1140/epjc/s10052-026-15425-5
Regular Article - Theoretical Physics
Next-to-leading order analysis of 
production in photon–photon collisions at CEPC
School of Physics and Mechatronics Engineering, Guizhou Minzu University, 550025, Guiyang, People’s Republic of China
a
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Received:
24
November
2025
Accepted:
7
February
2026
Published online:
25
February
2026
Abstract
We systematically investigate the production of in 
collisions within nonrelativistic QCD (NRQCD) factorization, with the direct-photon channel calculated specifically up to the next-to-leading order in 
. Calculations for CEPC energy region show the resolved photon contribution is negligible, while the direct photon process dominates, yielding substantial annual 
yields. Significant modifications to polarization parameters emerge from color-octet mechanisms, and different NRQCD long distance matrix elements (LDMEs) further yield distinct polarization patterns. Furthermore, the polarization predictions are highly sensitive to the 3![Mathematical equation: $$P_J^{[8]}$$](/articles/epjc/abs/2026/02/10052_2026_Article_15425/10052_2026_Article_15425_tex_eq8.png)
LDME, while being insensitive to the 1![Mathematical equation: $$S_0^{[8]}$$](/articles/epjc/abs/2026/02/10052_2026_Article_15425/10052_2026_Article_15425_tex_eq9.png)
and 3![Mathematical equation: $$S_1^{[8]}$$](/articles/epjc/abs/2026/02/10052_2026_Article_15425/10052_2026_Article_15425_tex_eq10.png)
LDMEs. Leveraging the cleaner environment of 
collisions versus hadronic processes, the production of associated with a photon in collisions provides a high-precision platform to test LDMEs universality and resolve longstanding polarization puzzles.
© The Author(s) 2026
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