arXiv subjects

Tomohito Shiga

Publications and source records attributed to Tomohito Shiga.

2 recordsLinked to original sources

arXiv2026

Exact WKB and Quantum Periods for Extremal Black Hole Quasinormal Modes

We apply exact WKB analysis to the spectral problem arising in black hole perturbation theory. The boundary conditions for quasinormal modes lead to exact quantization conditions for the complex frequencies. To solve these conditions, one needs to evaluate the so-called quantum periods, or Voros symbols. For scalar perturbations of extremal Reissner--Nordstr\"om and Kerr black holes, we compute these quantities up to very high orders in the WKB expansion and perform Borel--Pad\'e resummation. The resulting resummed quantization conditions successfully reproduce the correct quasinormal mode frequencies with high precision.

hep-th↗

arXiv2025

Fluid Boundary Conditions from AdS/BCFT

In this paper, we initiate our program to classify conformal fluid boundary conditions, by utilizing the fluid/gravity correspondence in the AdS/BCFT correspondence. The AdS/BCFT correspondence is a conjectured duality between a quantum gravity in asymptotically AdS spacetime with an end-of-the world brane and a boundary conformal field theory (BCFT). We show that a choice of boundary condition for the metric on the end-of-the world brane naturally leads to specific boundary conditions for velocity field and temperature field of BCFT in the hydrodynamic limit. We analyze the Neumann, Dirichlet and Conformal boundary conditions for the metric on the end-of-the world brane, and discuss their implications for conformal fluid boundary conditions.

hep-th↗