String Seminar
String Seminar
Title: Single-Sided Black Holes in Double-Scaled SYK Model and No Man's Island
Abstract: We study a single-sided black hole with an end-of-the-world (EoW) brane behind the horizon in the double-scaled SYK (DSSYK). The new Hamiltonian is a deformation of the original DSSYK Hamiltonian with an extra exponential wormhole length operator, which leads to a new chord diagram rule. The boundary algebra is defined as generated by the new Hamiltonian and boundary matter.
There is an alternative but equivalent definition with a q-coherent state due to a nontrivial isomorphism of the vN algebra of DSSYK. This isomorphism induces a unitary equivalence, which yields a surprising result that the boundary algebra of a single-sided black hole in DSSYK has a non-trivial commutant and is a type II1 vN factor. It follows that the full bulk reconstruction from the boundary is impossible, and there is a "no man's island" behind the horizon in the semiclassical JT limit. Inspired by the EoW brane, we construct a family of matter-brane states with an arbitrary number of matter chords and behaving like an EoW brane. They exactly solve the full spectrum of DSSYK.
We take different ways to understand the nontrivial commutant. We show that the commutant is complex on chord number basis and thus non-geometric. In the semiclassical JT limit, the commutant becomes the canonical purification of the boundary algebra and claims the no man's island. In the context of Hawking radiation after Page time, the unitary equivalence is interpreted as encoding the canonical purification into the old Hawking radiation and the no man's island has the same essence as the island.
Including the exponential wormhole length operator independently, the boundary algebra is extended to all bounded operators and reconstructs the no man's island. This can be regarded as a different choice for the definition of boundary algebra. This type I∞ algebra is closely related to the EoW brane in Kourkoulou-Maldacena.
Based on: https://arxiv.org/abs/2511.01978
Date:
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Location:
CP 303
Event Series:
Physics & Astronomy String Seminar
Gerald Hoehn, Kansas State University
Title: Codes, Lattices and Vertex Operator Algebras
Abstract: TBA
Date:
Location:
CP 303
Event Series:
String Seminar
Title:
The Gravitational Path Integral and Axion Wormholes
Abstract:
We investigate the relevance of axiom wormholes to the AdS/CFT factorization problem using Lorentz-signature gravitational path integrals.
Date:
Location:
Zoom
Event Series:
Physics & Astronomy String Seminar
Title: Hamiltonian approach to near extremal black hole physics
Abstract: Much progress has been made in recent years on understanding near-extremal black holes, primarily through the Euclidean path integral. These findings include large backreaction effects at both classical and quantum levels. However, a Lorentzian formulation of these effects, as needed to describe black holes formed from collapse along with other dynamical processes, is not well understood. I will describe an approach to this problem based on the Hamiltonian formulation of gravity. In this formulation we can make contact with earlier Euclidean results while also generalizing to inherently Lorentzian processes like black hole formation.
Date:
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Location:
CP 303
Event Series:
Physics & Astronomy String Seminar
Title: Exact Transition Amplitudes in Liouville CFT and the Cigar
Abstract: We study exact transition amplitudes in certain 2D CFTs — Liouville theory and the SL(2,R)/U(1) coset model describing Witten's 2D black hole. Using bootstrapped conserved currents and a generating functional approach based on canonical transformations, we compute these transitions both recursively and via functional integral representations. The tree-level evaluation of the generating functional reproduces exact results, while providing a diagrammatic framework for loop corrections. We also find that the statistics of Liouville transition elements at higher oscillator levels exhibit level repulsion.
Date:
-
Location:
CP 303
Event Series: