[NTU-NCTS String Seminar] Do all Euclidean saddles contribute to the gravitational partition function?

  • Event Date: 2024-02-02
  • High energy theory
  • Speaker: Shoichiro Miyashita (National Dong-Hua University)  /  Host: Profs. Yu-tin Huang & Pei-Ming Ho (NTU)
    Place: Rm. 815, Dept. of Physics, NTU

Title:Do all Euclidean saddles contribute to the gravitational partition function?
Speaker:Shoichiro Miyashita (National Dong-Hua University)
Date:2024/02/02 (Fri.)

The saddle point approximation of the gravitational partition function may be a good method for investigating thermodynamical properties of gravitating systems, although there exists the integration contour problem. For some systems, when the spatial section of the boundary is of finite volume, there can exist two types of saddle point in the S2×Disc topology sector: One is (Euclidean) BH and the other is, what I call, BG. A BG is a geometry whose area of the bolt is larger than that of the boundary sphere, and BGs are implicitly or sometimes explicitly excluded from the partition function in the literature. In this talk, I will present how thermodynamical properties change if we include the contribution of BG in two simple systems, pure gravity with a positive cosmological constant and Einstein-Maxwell system. The conclusion is that it seems BGs are (sometimes) necessary. Although I cannot give a definite answer, I will show the reasons why I think so and the possible answers to the question.