BAPO: Stabilizing Off-Policy Reinforcement Learning for LLMs via Balanced Policy Optimization with Adaptive Clipping - Xi, Zhiheng; Guo, Xin; Nan, Yang; Zhou, Enyu; Shen, Junrui; Chen, Wenxiang; Liu, Jiaqi; Huang, Jixuan; Deng, Xun; Zhang, Zhihao; Guo, Honglin; Lei, Zhikai; et al. (International Conference on Learning Representations, 2026)