How Far Are We from Genuinely Useful Deep Research Agents? - Dingling Zhang; He Zhu; JinCheng Ren; Kangqi Song; Xinran Zhou; Boyu Feng; Shudong Liu 009; Jiabin Luo; Weihao Xie; Zhaohui Wang; Tianrui Qin; King Zhu; et al. (CoRR, 2025)