open https://ocw.u-tokyo.ac.jp/course_11330/
open https://www.youtube.com/@GraduatePhysics/videos
open https://www.youtube.com/@tobiasjosborne/playlists
open https://www.youtube.com/@iroganai
open https://www.youtube.com/@ron1827/playlists
open https://www.youtube.com/@qftgeometry8987/videos
open
open https://www.youtube.com/watch?v=mWj1ZEQTI8I&list=PLyQSN7X0ro203puVhQsmCj9qhlFQ-As8e&index=1
We review recent work on holography for finite area causal diamonds and explore its implications for the description of such diamonds in the Anti-deSitter space Conformal Field Theory correspondence. We argue that the algebra of operators in a finite area diamond is well defined in a UV cutoff tensor network construction, but is not related in any simple way to any infinite von Neumann sub-algebra of the boundary algebra or its cross product. Our argument relies on a novel construction of tensor networks that preserves rotation invariance.
In this paper, we derive a soft photon theorem and a soft gluon theorem in the de Sitter spacetime from the Ward identity of the near cosmological horizon large gauge transformation. Taking the flat limit of the de Sitter spacetime, the soft theorems naturally recover the corresponding flat spacetime soft theorems.
These notes are self-contained, with the first six chapters used for a one-semester course with recommended texts by Wald, Misner, Thorne, and Wheeler (MTW), and, particularly for gravitational waves, by Schutz and by Thorne and Blandford. ...
[2308.05802] Effective gravitational action for 2D massive Majorana fermions on arbitrary genus Riemann surfaces https://arxiv.org/abs/2308.05802
We explore the effective gravitational action for two-dimensional massive Euclidean Majorana fermions in a small mass expansion, continuing and completing the study initiated in a previous paper. We perform a detailed analysis of local zeta functions, heat kernels, and Green's functions of the Dirac operator on arbitrary Riemann surfaces. We obtain the full expansion of the effective gravitational action to all orders in m2. For genus one and larger, this requires the understanding of the role of the zero-modes of the (massless) Dirac operator which is worked out.
This report provides Green's functions (classical propagators) of gravitational fields of vierbein and spin-connection in general relativity. The existence of Green's function of the Laplace operator in curved space with an indefinite metric is ensured owing to the Hodge harmonic analysis. The analyticity of Green's function is naturally determined intrinsically, keeping a causality. This report proposed a novel definition of the momentum space in curved space-time and the linearisation of the Einstein equation as a free field consistent with that for the Yang-Mills gauge field. The proposed linearisation does not utilize the weak-field approximation; thus, the method applies to highly caved space-time. We gave two examples of Green's function of gravitational fields, the plane wave solution and the Schwarzschild solution.
