Near-horizon BF bounds for the t+ KK tower on extremal AdS5 black holes
Abstract
We study the charged Breitenlohner--Freedman (BF) bound for all horizon harmonics of the type IIB t+ Kaluza--Klein tower on extremal charged AdS5 black holes with equal rotations. The scalar equation follows from maximal five-dimensional gauged supergravity at level zero and the linearized exceptional-field-theory equations at higher levels. For aligned charge and rotation, a quadratic form in charge and spin changes signature on the curve of supersymmetric (BPS) black holes, where every mode satisfies the bound. Above the curve, where ΩH>1, every black hole has a violating mode, although no finite truncation in level or spin detects violation at every such black hole. Below the curve, where ΦH>1, the BF-passing set is confined to a thin strip and controlled by charge and spin discreteness. At large radius and fixed rotation, a level-four mode with spin proportional to the radius violates the bound even where all U(2) singlets satisfy it. These results concern the near-horizon BF bound of one tower in two-derivative supergravity; full radial stability remains open.
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BibTeX
@misc{liu2026nearhorizon,
title = {{Near-horizon BF bounds for the $t^+$ KK tower on extremal AdS$_5$ black holes}},
author = {Xiao-Long Liu and Zheng Miao and Yuezhang Tang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.37908},
eprint = {2610.37908},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.37908},
}
RIS
TY - UNPB
TI - Near-horizon BF bounds for the t^+ KK tower on extremal AdS_5 black holes
AU - Xiao-Long Liu
AU - Zheng Miao
AU - Yuezhang Tang
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.37908
UR - https://arxiv.org/abs/2610.37908
AB - We study the charged Breitenlohner--Freedman (BF) bound for all horizon harmonics of the type IIB t^+ Kaluza--Klein tower on extremal charged AdS_5 black holes with equal rotations. The scalar equation follows from maximal five-dimensional gauged supergravity at level zero and the linearized exceptional-field-theory equations at higher levels. For aligned charge and rotation, a quadratic form in charge and spin changes signature on the curve of supersymmetric (BPS) black holes, where every mode satisfies the bound. Above the curve, where Ω_H>1, every black hole has a violating mode, although no finite truncation in level or spin detects violation at every such black hole. Below the curve, where Φ_H>1, the BF-passing set is confined to a thin strip and controlled by charge and spin discreteness. At large radius and fixed rotation, a level-four mode with spin proportional to the radius violates the bound even where all U(2) singlets satisfy it. These results concern the near-horizon BF bound of one tower in two-derivative supergravity; full radial stability remains open.
ER -