本项目的主要内容是超弦在三维渐进反德西特时空中的热动力学，特别是在Hagedorn温度附近的热动力学以及相转变。一个主要的研究目标是弦论在三维反德西特时空中的Horowitz-Polchinski弦的解，和它与BTZ黑洞之间的相转换，以及相关的Hagedorn转变。Horowitz-Polchinski弦是描述弦在温度趋近于Hagedorn温度附近的一个有效经典理论，它具有和BTZ黑洞很多相似性，包括自由能，熵等热力学性质。通过研究它们之间的相转化，我们期望会有助于进一步提升对黑洞微观结构等一些问题的认识。

The main context of this program is to study the thermodynamics of superstrings on the three-dimensional asymptotically Anti-de Sitter (AdS3) spacetimes. We mainly focus on the study of the thermodynamics around the Hagedorn temperature and the associated phase transitions. One of the main goals is to study the Horowitz-Polchinski strings (or known as string stars) on the asymptotically AdS3 spacetimes, and the possible phase transitions with BTZ black holes, as well as Hagedorn transitions. A Horowitz-Polchinski string on the AdS3 spacetimes is an effective theory describing strings on the AdS3 around the Hagedorn temperature. It shares many common thermodynamical features with a BTZ black hole such as free energy functions, entropies, etc. The study of the phase transitions would hopefully shed light on the understanding of the microstructures of black holes and other related issues.