Event Category: String Seminar

String Seminar:
Tuesdays at 3:40pm on campus

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Abstract: Recently, Akers et al. proposed a non-isometric holographic map from the interior of a black hole to its exterior. Within this model, we study properties of the black hole S-matrix, which are in principle accessible to observers who stay outside the black hole. Specifically, we investigate a scenario in which an infalling agent interacts with radiation both outside and … Read More

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“One approach to the Strong CP Problem (known as Nelson-Barr models) is to assume that parity is a gauge symmetry which is spontaneously broken in the world around us. In this talk, I will argue that the domain walls formed from spontaneous parity breaking are exactly stable. This stability can be understood as the result of an unusual sort of … Read More

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Abstract: I will describe the construction of entangled microstates of a pair of holographic CFTs whose dual semiclassical description includes big bang-big crunch AdS cosmologies in spaces without boundaries. The cosmology is supported by inhomogeneous heavy matter and it partially purifies the bulk entanglement of two auxiliary AdS spacetimes. In generic settings, the cosmology is an entanglement island contained in … Read More

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Abstract: The study of scattering amplitudes has recently revealed intriguing similarities between theories whose Lagrangian formulations are quite different. In particular, it has been shown that amplitudes in a web of theories (of flavored scalars, gluons, pions, gravitons, non-linear photons…) can be constructed using only a small set of universal building blocks, generalizing the so-called double copy between gauge and … Read More

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Abstract: Understanding how to prepare and count black hole micro-states by using the gravitational path integral is one of the most important problems in quantum gravity. Nevertheless, a state-by-state count of black hole microstates is difficult because the apparent number of degrees of freedom available in the gravitational effective theory can vastly exceed the entropy of the black hole, even in … Read More

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We construct approximately local observables, or “overlapping qubits”, using non-isometric maps and show that processes in local effective theories can be spoofed with a quantum system with fewer degrees of freedom, similar to our expectation in holography. Furthermore, the spoofed system naturally deviates from an actual local theory in ways that are similar to the features in quantum gravity. For … Read More

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Abstract: In this talk, I will propose a new formula for computing holographic Renyi entropies in the presence of multiple extremal surfaces. The proposal is based on computing the wave function in the basis of fixed-area states and assuming a diagonal approximation for the Renyi entropy that preserves replica symmetry at integer $n$. I will discuss conditions under which the … Read More

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Abstract: In a chaotic system, an initial small perturbation will eventually affect the whole system. In certain many-body systems, this effect is mediated by a “scramblon” field. In large N limit, scramblon exchange dominates, while self-interactions are suppressed by 1/N. But because the scramblon propagator grows exponentially in time, these self-interactions eventually become important. We make an initial study of … Read More

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Abstract:The double-scaled limit of the SYK model takes the number of fermions and their interaction number to infinity in a coordinated way. In this limit, two entangled copies of the SYK model have a bulk description of sorts known as the “chord Hilbert space.” We analyze a symmetry algebra acting on this Hilbert space, generated by the two Hamiltonians together … Read More