activity
20242026
collaborators

5 papers

hep-th2026

Instability thresholds for de Sitter and Minkowski spacetimes in holographic semiclassical gravity

Akihiro Ishibashi, Kengo Maeda, Takashi Okamura

We study the stability of -dimensional () de Sitter and Minkowski spacetimes within the framework of semiclassical gravity sourced by a strongly coupled quantum field w…

hep-th2025

Energy Conditions and Quantum Information

Norihiro Iizuka, Akihiro Ishibashi, Kengo Maeda +2

The concept of energy lies at the foundation of physical science. In general relativity and quantum field theory, the positivity and conservation of energy are encapsulated by the…

hep-th2025

Self-gravitating strings and quantum effects in two-dimensional gravity

Akihiro Ishibashi, Yoshinori Matsuo, Akane Tanaka

It is expected that when the string coupling is taken to be sufficiently small, a black hole turns into a bound state of self-gravitating fundamental strings. This state would be d…

hep-th2024

The higher dimensional instabilities of AdS in holographic semiclassical gravity

Akihiro Ishibashi, Kengo Maeda, Takashi Okamura

In the framework of AdS/CFT duality, we consider the semiclassical problem in general quadratic theory of gravity. We construct asymptotically global AdS and hyperbolic~(topologica…

hep-th2024

Quantum focusing conjecture in two-dimensional evaporating black holes

Akihiro Ishibashi, Yoshinori Matsuo, Akane Tanaka

We consider the quantum focusing conjecture (QFC) for two-dimensional evaporating black holes. The QFC is closely related to the behavior of the generalized entropy -- the sum of t…