QUARK: Robust Retrieval under Non-Faithful Queries via Query-Anchored Aggregation

TL;DR

QUARK is a training-free framework that enhances retrieval robustness against noisy, incomplete, or distorted user queries by modeling query uncertainty with multiple hypotheses and aggregating their signals anchored to the original query.

Contribution

It introduces a novel query-anchored aggregation method that explicitly models query uncertainty, improving retrieval robustness without additional training.

Findings

QUARK improves recall, MRR, and nDCG on BEIR benchmarks.

It is robust to the number of recovery hypotheses.

Anchored aggregation outperforms unanchored pooling methods.

Abstract

User queries in real-world retrieval are often non-faithful (noisy, incomplete, or distorted), causing retrievers to fail when key semantics are missing. We formalize this as retrieval under recall noise, where the observed query is drawn from a noisy recall process of a latent target item. To address this, we propose QUARK, a simple yet effective training-free framework for robust retrieval under non-faithful queries. QUARK explicitly models query uncertainty through recovery hypotheses, i.e., multiple plausible interpretations of the latent intent given the observed query, and introduces query-anchored aggregation to combine their signals robustly. The original query serves as a semantic anchor, while recovery hypotheses provide controlled auxiliary evidence, preventing semantic drift and hypothesis hijacking. This design enables QUARK to improve recall and ranking quality without sacrificing robustness, even when some hypotheses are noisy or uninformative. Across controlled simulations and BEIR benchmarks (FIQA, SciFact, NFCorpus) with both sparse and dense retrievers, QUARK improves Recall, MRR, and nDCG over the base retriever. Ablations show QUARK is robust to the number of recovery hypotheses and that anchored aggregation outperforms unanchored max/mean/median pooling. These results demonstrate that modeling query uncertainty through recovery hypotheses, coupled with principled anchored aggregation, is essential for robust retrieval under non-faithful queries.