Factual Density (FD*)

Factual Density (FD*): A Retrieval Optimization Signal for Multi-Source RAG in Medical AI

This paper introduces Factual Density (FD*), a retrieval reranking signal that measures the proportion of verified atomic claims per token to address what the authors call the 'Expert Blindness Effect' in standard RAG pipelines. Using the NexusAgentics Ghost Audit preprocessing pipeline and Z-score normalization within length bins, FD* is validated as a length-independent signal. Evaluated on the HealthFC benchmark (750 health claims), FD*-optimized retrieval achieved 100% systematic review saturation in top-5 results, surfacing Cochrane evidence that cosine similarity ranked outside the top ten. The study is limited to 25 verified mappings across seven claims, with full n=50 validation deferred to future work.