7 papers
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…
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…
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…
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…
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…
Symmetry breaking of -dimensional AdS in holographic semiclassical gravity
Akihiro Ishibashi, Kengo Maeda, Takashi Okamura
We show that -dimensional AdS spacetime can be semiclassically unstable due to strongly interacting quantum field effects. In our previous paper, we have pointed out the possibi…
A note on no-hair properties of static black holes in four and higher dimensional spacetimes with cosmological constant
Akihiro Ishibashi, Satoshi Matsumoto, Yuichiro Yoneo
We study no-hair properties of static black holes in four and higher dimensional spacetimes with a cosmological constant. For the vanishing cosmological constant case, we show a no…