DeepResearchGym: A Free, Transparent, and Reproducible Evaluation Sandbox for Deep Research. - João Coelho; Jingjie Ning; Jingyuan He; Kangrui Mao; Abhijay Paladugu; Pranav Setlur; Jiahe Jin; Jamie Callan; João Magalhães; Bruno Martins 001; Chenyan Xiong (CoRR, 2025)