Ruijia Zhang

PhD Candidate, Applied Mathematics & Statistics
Johns Hopkins University, Baltimore, MD, USA

📧 rzhan127@jh.edu 🌐 Google Scholar

About me

I am a PhD candidate in the Department of Applied Mathematics and Statistics at Johns Hopkins University, starting in August 2024.
My research is broadly motivated by the question of how to make reliable and robust decisions under uncertainty. I work on problems at the intersection of applied probability, optimization, and reinforcement learning. My recent interests focus on LLM Fine-tuning and Distributionally Robust Optimization.

Research

Publications

• POLAR: A Pessimistic Model-based Policy Learning Algorithm for Dynamic Treatment Regimes
  Major Revision at Journal of the American Statistical Association (JASA)
  🏆 ASA Nonparametric Statistics Section Best Student Paper Awards for the Joint Statistical Meetings (JSM) 2026
  Ruijia Zhang, Zhenglin Qi, Yue Wu, Xiangyu Zhang, Yanxun Xu.
• Understanding Inverse Reinforcement Learning under Overparameterization: Non-Asymptotic Analysis and Global Optimality
  AISTATS 2025
  Ruijia Zhang, Siliang Zeng, Chenliang Li, Alfredo Garcia, Mingyi Hong.
• Improved Rates of Differential Private Nonconvex Strongly Concave Minimax Optimization via Gradient Differences
  AAAI 2025
  Ruijia Zhang, Mingxi Lei, Meng Ding, Zihang Xiang, Jinhui Xu, Di Wang.

Ongoing Works

• Geometry-Preserving Orthonormal Initialization for Low-Rank Adaptation in Reinforcement Learning. In Submission for ICML 2026, collaborated with Meta Super Intelligence Team and xAI.
  Ruijia Zhang, Jiacheng Zhu, Andy Su, Hanqing Zhu, Laixi Shi.

• Learning Optimal Robust Policies under Observational Data with Causal Transport. To be submitted to Operations Research.
  Ruijia Zhang, Luhao Zhang, Michael Lingzhi Li.

Teaching

Graduate Teaching Assistant, JHU

• EN.553.639 Time Series Analysis (Spring 2026)
• EN.553.744 Data Science Methods for Large-Scale Graphs (Spring 2025)
• EN.553.642 Investment Science (Fall 2024&2025)

Undergraduate Student Teaching Fellow, CUHK(SZ)

• MAT2002 Ordinary Differential Equations (Spring 2024)
• MAT3007 Optimization (Fall 2023)

Awards 🏆

• ASA Nonparametric Statistics Section Best Student Paper Awards for the Joint Statistical Meetings (JSM) 2026
• International Conference on Continuous Optimization (ICCOPT) 2025 Student Grant

Education