## Upcoming Seminars

Date/Place | Nov. 20th (Tue.) 15:30-16:30 / H711 |
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Name | Tomonori Ugajin (OIST) |

Title | Modular Hamiltonians of excited states, OPE blocks and emergent bulk fields |

Abstract | We study the entanglement entropy and the modular Hamiltonian of slightly excited states reduced to a ball shaped region in generic conformal field theories. We set up a formal expansion in the one point functions of the state in which all orders are explicitly given in terms of integrals of multi-point functions along the vacuum modular flow, without a need for replica index analytic continuation. We show that the quadratic order contributions in this expansion can be calculated in a way expected from holography, namely via the bulk canonical energy for the entanglement entropy, and its variation for the modular Hamiltonian. The bulk fields contributing to the canonical energy are defined via the HKLL procedure. In terms of CFT variables, the contribution of each such bulk field to the modular Hamiltonian is given by the OPE block corresponding to the dual operator integrated along the vacuum modular flow. These results do not rely on assuming large N or other special properties of the CFT and therefore they are purely kinematic. |

Date/Place | Nov. 27th (Tue.) 15:30-16:30 / H711 |
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Name | Kazuya Yonekura (Kyushu University) |

Title | Black hole information and Reeh-Schlieder theorem |

Abstract | I will talk about implications of the Reeh-Schlieder theorem on the black hole information problem. In particular, I will argue that the Reeh-Schlieder theorem implies that “information” cannot be localized, and hence there is no well-defined concept of “information which is inside/outside event horizon”. Therefore, I claim that the black hole information problem is not well-formulated from the beginning. |