# E-lab Seminar

## Upcoming

Date | Mon Jun 12 2023 |
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Speaker |
Shoto Aoki (Osaka Univ.) |

Title | Curved domain-wall fermion and its anomaly inflow |

Abstract | We investigate the effect of U(1) gauge field on lattice fermion systems with a curved domain-wall mass term. In the same way as the conventional flat domain-wall fermion, the chiral edge modes appear localized at the wall, whose Dirac operator contains the induced gravitational potential as well as the U(1) vector potential. In the case of S1 domain-wall fermion on a twodimensional flat lattice, we find a competition between the Aharonov-Bohm(AB) effect and gravitational gap in the Dirac eigenvalue spectrum, which leads to anomaly of the time-reversal (T) symmetry. Our numerical result shows a good consistency with the Atiyah-Patodi-Singer index theorem on a disk inside the S1 domain-wall, which describes the cancellation of the T anomaly between the bulk and edge. When the U(1) flux is squeezed inside one plaquette, and the AB phase takes a quantized value π mod 2 π Z, the anomaly inflow drastically changes: the strong flux creates another domain-wall around the flux to make the two zero modes coexist. This phenomenon is also observed in the S2 domain-wall fermion in the presence of a magnetic monopole. We find that the domain-wall creation around the monopole microscopically explains the Witten effect. |

Remarks | |

Slide/Video |

Date | Mon Jun 26 2023 |
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Speaker |
Akihiro Ishibashi (Kindai University) |

Title | Semiclassical Einstein equations from holography and boundary dynamics |

Abstract | We consider how to formulate semiclassical problems in the context of the AdS/CFT correspondence, based on the proposal of Compere and Marolf [arXiv:0805.1902]. Our prescription involves the effective action with self-action term for boundary dynamical fields, which can be viewed as imposing mixed boundary conditions for the gravity dual. We derive the semiclassical Einstein equations sourced by boundary CFT stress-energy tensor. Analyzing perturbations of the holographic semiclassical Einstein equations, we find a universal parameter which controls the contribution from boundary CFTs and specifies dynamics on the AdS boundary. As a simple example, we examine the semiclassical Einstein equations in 3-dimensions with 4-dimensional AdS gravity dual, and show that the boundary BTZ black hole with vanishing expectation value of the stress-energy tensor becomes unstable due to the backreaction from quantum stress-energy tensor when the parameter exceeds a certain critical value. This talk is based on the joint work with K. Maeda and T. Okamura, 2301.12170 [hep-th] |

Remarks | |

Slide/Video |

Date | Tue Jul 04 2023 |
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Speaker |
Shanming Ruan (YITP) |

Title | Complexity=Anything: Singularity Probes |

Abstract | We investigate how the complexity=anything observables can be used to investigate the interior geometry of AdS black holes. In particular, we illustrate how the flexibility of the complexity=anything approach allows us to systematically probe the geometric properties of black hole singularities. We contrast our results for the AdS Schwarzschild and AdS Reissner-Nordstrom geometries, i.e., for uncharged and charged black holes, respectively. In the latter case, the holographic complexity observables can only probe the interior up to the inner horizon. |

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Slide/Video |

Date | Mon Jul 24 2023 |
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Speaker |
Kazuki Tanaka (Niigata University) |

Title | TBA |

Abstract | TBA |

Remarks | |

Slide/Video |