Past Events
Kyoto/NTU/OIST Fundamental Theory Workshop
2018年11月24日 (土) 14:00 〜 2018年11月27日 (火) 15:00Joint High Energy Theory workshop between Kyoto University, National Taiwan University and OIST. Additional external speakers are Song He, Eugene Skvortsov, Julian Sonner and Kazuya Yonekura.
Program & Schedule in attached PDF.
QG group meeting: Black hole microstate counting for BTZ black hole
2018年11月12日 (月) 15:30Quantum Gravity Group Meeting
Title: Black hole microstate counting for BTZ black hole
Speaker: Vyacheslav Lysov, Quantum Gravity Unit (Neiman)
QG group meeting: Conformal Bootstrap at Finite Temperature
2018年10月22日 (月) 15:30Quantum Gravity Group Meeting:
Title: Conformal Bootstrap at Finite Temperature
Speaker: Sudip Ghosh, Quantum Gravity Unit (Neiman)
[Seminar] "Vacuum decay rate in the standard model and beyond" by Dr. Yutaro Shoji
2018年10月2日 (火) 15:00 〜 16:00Speaker: Dr. Yutaro Shoji from Nagoya University
Abstract:
The electroweak vacuum is not absolutely stable in the standard model and various models beyond the standard model. This is due to an appearance of another deeper vacuum, into which the electroweak vacuum can decay. The decay proceeds through quantum tunneling and the rate is expressed with an exponential suppression factor and a pre-factor. The suppression factor has been calculated in many papers, but a naive dimensional analysis has been usually adopted for the pre-factor.
We have pointed out that such an evaluation can suffer from large quantum corrections and it is important to calculate the pre-factor as well.
To calculate the pre-factor, we had problems in a gauge sector; its gauge invariance is not explicitly shown, and there appear zero modes, which we could not deal with.
We have solved these problems and made it possible to determine vacuum decay rates precisely.
As applications, we analyzed the decay rates in the standard model and its fermionic extensions. We also provide a public code, which can be used for models that exhibit classical scale invariance at a high energy scale.
QG group meeting: Fluid/gravity correspondence
2018年9月10日 (月) 15:30 〜 17:00This is the weekly QG group meeting.
Speaker: Vyacheslav Lysov
Title: Fluid/Gravity Correspondence
Journal club seminar: Geometry of Complexity
2018年9月7日 (金) 15:00Discussion by Vyacheslav Lysov on Geometry of Complexity.
QG group meeting: null hypersurface geometry
2018年9月3日 (月) 15:30 〜 17:00QG group meeting
Speaker: Yasha Neiman
Title: Introduction to the geometry of null hypersurfaces
[Seminar] "TOPOLOGICAL DEFECTS, DEFORMED LATTICES AND SPONTANEOUS SYMMETRY BREAKING" by Dr. Vincenzo Vitagliano
2018年8月28日 (火) 15:00 〜 16:00Speaker: Dr. Vincnezo Vitagliano from Keio University
Abstract:
External conditions have a dramatic impact on the way dynamical symmetry breaking occurs. I will review some recent (and some less recent) results of symmetry breaking in curved spacetime. Flirting with the contemporary interest toward 2D engineered material, I will then move on potential applications on geometrically deformed lattices. In a curved background, the natural expectation is that curvature works toward the restoration of an internal symmetry. I will show instead that, for topological defects, the competing action of the locally induced curvature and of boundary conditions generated by the non-trivial topology allows configurations where symmetries can be spontaneously broken close to the core.
[Seminar] "Constraining Quantum Gravity from the Bottom-up" by Dr. Scott Melville
2018年8月14日 (火) 15:00 〜 16:00Gravity on large scales is relatively well understood. For galaxies, planets and apples: we have Einstein’s General Relativity with which to make accurate predictions. But on small scales, where quantum mechanics becomes important, gravity is more difficult to understand, and as a result we lack precise descriptions of various natural phenomena (such as black holes).
One way to make progress in in our search for quantum gravity is to start from the large scale theory we know and love (at the ‘bottom’), and look for ways in which it may be modified and improved as we zoom in to smaller scales (going ‘up’ to a more fundamental theory).
Recent progress in ‘Effective Field Theory’ may shed some light on the connections between large and small scale physics. By exploiting certain physical properties of scattering probabilities (e.g. that they are unitary, causal and local), one can derive an infinite number of constraints which any large scale theory must satisfy in order to admit a sensible small scale completion.
In this talk, I will provide an overview of these new ‘positivity constraints’, and discuss their implications for quantum gravity.
QG group meeting - the complex action of GR and black hole entropy
2018年8月13日 (月) 15:30 〜 17:00QG group meeting
Speaker: Yasha Neiman
Title: "The complex action of GR and black hole entropy"