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JointCQ: Improving Factual Hallucination Detection with Joint Claim and Query Generation

Paper · 2026 · Fan Xu, Huixuan Zhang, Zhenliang Zhang et al.

Summary

The paper targets factual hallucination detection in open-domain question answering. Retrieval-based checking pipelines usually split an answer into claims, write search queries, gather evidence and then verify each claim. The authors argue that the first two steps are weak: claims lose their context, and queries are too vague to retrieve useful evidence. JointCQ replaces both steps with one finetuned model that outputs claims together with matching search queries in a single pass.

To train this model, the authors build synthetic data. Several open LLMs answer questions from ANAH-v2. Qwen3-32B then extracts claims and drafts a query for each claim. A dual filter keeps only good pairs: claims are checked for entailment, coverage and decontextualization, and queries for relevance, conciseness and usability.

In the full pipeline, the queries go to Google Search, and a Qwen3-14B verifier labels each claim using the retrieved snippets. The system beats strong baselines on several English and Chinese benchmarks. It relies only on open-source models, which keeps cost low and makes deployment easier.

Key points

  • Training data: questions come from ANAH-v2. Answers were produced by Qwen2.5-7B-Instruct, Llama-3.1-8B-Instruct, gemma-3-4b-it and glm-4-9b-chat.
  • Synthesis setup: claims and queries were generated by Qwen3-32B with 3-shot prompts. For claims, the examples were chosen by semantic similarity (paraphrase-multilingual-mpnet-base-v2) and by answer length.
  • Labels: each claim is tagged as Correct, Hallucinated or Unverifiable. Evidence is the top-10 Google snippets retrieved through the Serper API, and the retrieval component can be swapped for other search engines or local corpora.
  • Comparison with prior work: unlike FacTool and HaluAgent, which call closed-source APIs, JointCQ uses only open models. The authors also report that FacTool is more computationally expensive.
  • Limitations: the method is designed mainly for open-domain QA and depends on Google Search. Code is available at github.com/pku0xff/JointCQ.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

 Institutions

 Fields, topics and concepts

Cite

Cite as Fan Xu, Huixuan Zhang, Zhenliang Zhang, Jiahao Wang and Xiaojun Wan. 2026. JointCQ: Improving Factual Hallucination Detection with Joint Claim and Query Generation. Findings of the Association for Computational Linguistics: ACL 2026.

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.18653/v1/2026.findings-acl.58

@inproceedings{xu2026jointcq,
  title = {{JointCQ: Improving Factual Hallucination Detection with Joint Claim and Query Generation}},
  author = {Fan Xu, Huixuan Zhang, Zhenliang Zhang, Jiahao Wang and Xiaojun Wan},
  booktitle = {Findings of the Association for Computational Linguistics: ACL 2026},
  year = {2026},
  doi = {10.18653/v1/2026.findings-acl.58},
  url = {https://doi.org/10.18653/v1/2026.findings-acl.58}
}

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