SlugRAG at SemEval-2026 Task 8: Domain-Specific Fine-Tuning and Model Scaling for Multi-Turn RAG Retrieval

Pratibha Revankar, Jihye Kim, Umit Azirakhmet


Abstract
Multi-Turn Retrieval-Augmented Generation (MT-RAG) requires resolving context-dependent ambiguities across conversational turns. We present a systematic evaluation of dense retrieval optimization for the MTRAGEval benchmark (Task 8, Subtask A: Retrieval Only), investigating training-time strategies and inference-time query reformulation across four diverse English-language domains: CLAPNQ (legal/patent), FIQA (financial), GOVT (government documents), and CLOUD (cloud computing). Our experiments demonstrate that domain-specific fine-tuning yields the most substantial gains, with our best CLAPNQ model achieving Recall@10 of 0.6016 and nDCG@10 of 0.4981—representing 58.3\% and 66.0\% improvements over the pre-trained BGE baseline. Domain-specific models average 44.3\% improvement in Recall@10 and 47.8\% in nDCG@10 across all domains. Additionally, fine-tuning larger embedding models (BGE-large) achieves the best overall performance (nDCG@10: 0.5101, Recall@10: 0.6221), highlighting the complementary impact of model capacity and domain adaptation.
Anthology ID:
2026.semeval-1.135
Volume:
Proceedings of the 20th International Workshop on Semantic Evaluation (2026)
Month:
July
Year:
2026
Address:
San Diego, California, USA
Editors:
Ekaterina Kochmar, Debanjan Ghosh, Kai North, Mamoru Komachi
Venues:
SemEval | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
981–987
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URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.135/
DOI:
Bibkey:
Cite (ACL):
Pratibha Revankar, Jihye Kim, and Umit Azirakhmet. 2026. SlugRAG at SemEval-2026 Task 8: Domain-Specific Fine-Tuning and Model Scaling for Multi-Turn RAG Retrieval. In Proceedings of the 20th International Workshop on Semantic Evaluation (2026), pages 981–987, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
SlugRAG at SemEval-2026 Task 8: Domain-Specific Fine-Tuning and Model Scaling for Multi-Turn RAG Retrieval (Revankar et al., SemEval 2026)
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https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.135.pdf