Beyond Polarization: The Generative Constraint of Chain-of-Thought in Pointwise Reranking

Xiaoyang Chen, Jie Liu, Haijin Liang, Haibo Shi, Jin Ma, Ben He, Yingfei Sun, Dezhi Ye


Abstract
In pointwise document reranking, Chain-of-Thought models typically underperform direct scoring models. While existing diagnostics attribute this to inferior classification, score polarization, or calibration breakdown, whether targeted training can bridge this gap remains unclear. Our empirical study first confirms that this gap is stable across scales up to 32B parameters, ruling out model and data capacity confounders. We then apply stress tests utilizing reinforcement learning, fine-grained supervision, and architectural decoupling to explicitly repair these deviations. Although these interventions improve classification accuracy and absolute scores, the relative ranking gap persists. These findings suggest that, within the pointwise scoring paradigm, routing continuous relevance semantics through discrete text constrains ranking signal resolution, revealing a bottleneck that is stable and difficult to overcome under current standard methods, rather than an easily resolvable training bias.
Anthology ID:
2026.findings-emnlp.987
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
20854–20865
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.987/
DOI:
10.18653/2026.findings-emnlp.987
Bibkey:
Cite (ACL):
Xiaoyang Chen, Jie Liu, Haijin Liang, Haibo Shi, Jin Ma, Ben He, Yingfei Sun, and Dezhi Ye. 2026. Beyond Polarization: The Generative Constraint of Chain-of-Thought in Pointwise Reranking. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 20854–20865, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Beyond Polarization: The Generative Constraint of Chain-of-Thought in Pointwise Reranking (Chen et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.987.pdf