Events at 402 Classroom Physics South Hall, Campus

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Abstract: I will explore the promising potential of blazars — active galactic nuclei with relativistic jets pointed towards Earth — as ideal laboratories for studying sub-GeV Dark Matter phenomenology. Specifically, I will discuss how blazar-boosted Dark Matter could be detected by neutrino experiments, as well as the recently proposed idea that the 2017 detection of a high-energy neutrino from the … Read More

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Abstract:One of the fundamental problems in quantum gravity is to describe the experience of a gravitating observer in generic spacetimes. In this talk, I will discuss a frameworkfor describing non-perturbative physics relative to an observer using the gravitational path integral, which was recently introduced in https://arxiv.org/pdf/2501.02632. I will describe our proposal for an observer that lives in a closed universe and … Read More

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With the recommendation of the P5 panel for “an aggressive R&D program that, while technologically challenging, could yield revolutionary accelerator designs that chart a realistic path to a 10 TeV pCM collider” multiple future collider options are discussed within the HEP community. Several (less discussed) options, such as same sign lepton or photon colliders, are currently being explored in Berkeley … Read More

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An early highlight of quantum topology was the observation that the Jones polynomial — and many other knot and link invariants — arise from braided monoidal categories of quantum group representations. In hindsight, this can be understood as underlying reason for the existence  of associated topological quantum field theories (TQFTs) in 3 and 4 dimensions. Not much later, Khovanov discovered … Read More

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Abstract:  We construct algebras of diff-invariant observables in a global de Sitter universe with two observers and a free scalar QFT in two dimensions. We work in the strict G_N→0 limit, but allow the observers to have an order one mass in cosmic units. The observers are fully quantized. In the limit when the observers have infinite mass and are … Read More

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Abstract: I will address the question of how background independent target space physics emerges in string theory. The point of view I will take is to identify the configuration space of target space with the space of 2d worldsheet QFTs. On-shell configurations are identified with c=0 worldsheet theories (i.e. a c=26 matter sector), and non-conformal QFTs correspond to generic off-shell … Read More

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I will discuss some work in progress computing the norm of the Hartle-Hawking state in the simple model of pure three-dimensional gravity with positive cosmological constant. To one-loop order and including the contributions from universes with sphere boundaries in the far future, the result appears to be exp(|Z|) with Z the sphere partition function of 3d gravity.

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There has been a recent controversy over whether the photon-axion coupling is quantized (in appropriate units) or not. It was claimed that this was a deep theorem but counter-examples seemed to show otherwise resulting in an “academic discussion” in which the participants could not come to a shared conclusion.  In this talk I will examine the axion hidden in the … Read More

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Abstract:Schur quantization refers to a particular type of representation of the quantized algebras of functions on Coulomb branches of vacua of N=2, d=4 supersymmetric quantum field theories,  providing a quantum theoretical interpretation of the Schur indices. My talk will describe how the  Schur quantization encodes key aspects of the low energy physics of the underlying theory, and how it provides a new quantization of … Read More

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Abstract: In recent years, the Euclidean gravitational path integral has proven to be a reliable tool for studying quantum mechanical aspects of black holes. An important quantity that can help us probe whether black holes behave like conventional quantum mechanical systems is the supersymmetric index computed directly from the gravitational path integral. In this talk, I will discuss the issue … Read More