Event Category: String Seminar

String Seminar:
Tuesdays at 3:40pm on campus

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We describe an unexpected application of geometry of the space of gauge fields in two dimensional Yang-Mills theory, the subject of celebrated works of Narasimhan-Seshadri and Atiyah-Bott, to the active domain of research in condensed matter physics: the search for high-Tc superconductivity in exotic materials. Specifically, we shall clarify the meaning of the phenomenon of “magic angles” in the physics … Read More

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We consider the algebra of gravitational perturbations of the subregion of spacetime corresponding to the exterior of a black hole or the static patch of de Sitter. The algebra of gravitational perturbations are subject to constraints arising from the group of large gauge transformations of the subregion. Physically, these constraints arise due to the backreaction of gravitational perturbations on the … Read More

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Abstract: In this talk, I will discuss the one-loop determinant around axion wormholes in de Sitter. I will begin by reviewing these solutions, and explain our strategy to compute the one-loop determinant around them. I will then discuss general features of the one-loop spectrum, including the phase of the path integral around these solutions, and its interpretation for different values … Read More

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Abstract: I will study planar, maximally supersymmetric 4d EFTs that reduce to \mathcal{N}=4 SYM at low energies and show that novel constraints arise from the six-point amplitude. By constructing the six-scalar amplitude and imposing supersymmetry together with standard tree-level factorization, assuming parity-even scalar contact terms, I find striking nonlinear relations among the four-point Wilson coefficients. These relations collapse much of … Read More

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Abstract: The finite N BPS spectrum of the symmetric orbifold CFT of K3 contains “polar” states below the black hole threshold whose holographic origin has remained unclear. We propose a bulk prescription for computing these degeneracies exactly at finite N, given by a sum over one-loop partition functions of the IIB theory on spectrally-flowed (AdS3 x S3)/Z_K x K3 orbifold … Read More

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Abstract: I will describe a quantum mechanical model involving N interacting fermions without disorder that has a large N melonic expansion. In particular, it has the same Schwinger-Dyson equations and low energy physics as the \mathcal{N} = 2 supersymmetric SYK model. The model is SU(2) invariant, and the supercharge involves the SU(2) 3j symbol. I will conceptually explain why the … Read More

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Abstract: I propose to construct gauge invariant local observables in subregions in quantum gravity by placing the operators at slices with fixed extrinsic curvature K, thus using K as a physical clock. This construction can be made precise in 2d JT gravity with conformal matter. The resulting set of gauge invariant observables form a type II von Nuemann algebra. This … Read More

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I will derive the analytic structure of the S-matrix for classical wave scattering on a Schwarzschild black hole in 4-dimensions. The argument relies on the analytic continuation of the gravitational potential, with the singularity behind the horizon playing a crucial role. We observe the emergence of Stokes phenomena leading to a surprising branch cut in the upper half plane, seemingly … Read More

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We revisit Dp-brane holography, constructing Coulomb-branch solutions that describe a spherical shell of Dp-branes. The resulting throat geometries contain a flat-space bubble in the infrared region, providing a concrete framework for exploring entanglement in flat-space holography. We argue that the presence of the flat-space bubble leads to an overall reduction in entanglement and a corresponding decrease in the effective number … Read More

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Abstract: I will discuss recent work on the path integral of pure 3D gravity on a finite region of spacetime, constructed by gluing together hyperbolic tetrahedra. In the dual CFT, this amplitude calculates statistics of black hole matrix elements. The exact path integral is computed by Conformal Turaev-Viro theory, a topological theory based on triangulations.