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摘要：Scalar-tensor theory not only serves as one of the most important tools for constructing models in cosmology and gravitational wave research but also offers a broad playground for exploring modified gravity. In this talk, I will first review the development of scalar-tensor theory over the past two decades. In particular, I will present our efforts to utilize spatially covariant gravity as an effective and efficient framework for developing higher-derivative scalar-tensor theories without introducing ghost degrees of freedom. I will then discuss our recent results in constructing two new classes of scalar-tensor theories based on this approach: one featuring parity-violating effects and the other incorporating multiple scalar fields. These developments expand the scope of scalar-tensor theories and open new avenues for theoretical exploration.
个人简介：Xian Gao is a professor at the School of Physics and Astronomy, Sun Yat-sen University. He obtained his Ph.D. from the Institute of Theoretical Physics, Chinese Academy of Sciences in 2010. Subsequently, he conducted postdoctoral research at Université Paris Diderot - Paris 7, Tokyo Institute of Technology, and The University of Tokyo. He joined Sun Yat-sen University in 2016. His primary research focuses on gravitational theory, cosmology, and gravitational waves. He has published over 60 academic papers, with more than 3,000 citations, and authored one textbook. He currently serves as a committee member of the Gravitation and Relativistic Astrophysics Division of the Chinese Physical Society.