Raju Venugopalan (Brookhaven) | 2-> n scattering in QCD and Gravity in Regge asymptotics: from amplitudes to shockwaves | September 5, 2025
We discuss the structure of 2-> n scattering in QCD and gravity in high energy Regge asymptotics and outline the remarkable double copies between the two in their construction, and in emergent shockwave descriptions in the two theories.
Clay Cordova (U Chicago) | Representation Theory of Solitons | September 12, 2025
Non-invertible symmetries are novel transformations of quantum systems that imply new selection rules and constraints on dynamics. We derive the implications of these symmetries on the particle spectrum of two dimensional QFTs. We show that these symmetries often imply degeneracies between particles and solitons and apply our analyses to examples ranging from integrable deformations of minimal models to two-dimensional QCD.
Matthew Reece (harvard) | Axions in QFT and Quantum Gravity | September 19, 2025
The QCD axion is well-studied as a solution to the Strong CP problem and a dark matter candidate. At the same time, one often hears that axions are ubiquitous in top-down string theory models of particle physics. I will discuss how both bottom-up and top-down considerations favor axion models where the axion is a mode of a higher-dimensional gauge field. I will provide a viewpoint on why the existence of axions could follow from general principles of quantum gravity, and what we might
Pedro Viera (Perimeter) | Huge Operators in AdS/CFT and Matrix Models | October 31, 2025
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Laurent Freidel (Perimeter) | Quantum Null Ray: Effective dynamics and localized gauge invariant observables | November 7, 2025
In this talk, I'll review the construction of gravitational constraints and of the corresponding phase space along generalized Horizons.
I will focus my expose on the study of the Raychauduri Constraint and its quantization, which describes the dynamics of quantum null rays. I will present a detailed construction of the null Ray phase space and the localized gauge-invariant observables. Such a construction requires the introduction of a preferred time frame called the dressing time, which includes edge modes that allow localization along a null ray interval. Gauge-invariant observables are then obtained by dressing the fields with the dressing time. We will see how the edge mode symplectic structure can be understood in terms of the integration of degrees of freedom complementary to chosen region and how the gauge invariant observables include the covariant area element as a generator of reorientation of the frame. Overall the dressing time this provides a gravitational description of a quantum reference frame.
Finally, we will describe how the quantization procedure can be encoded through an effective deformation of the gravitational phase space labelled by a central charge. If time permits, I'll comment on the role the central charge plays in resolving the fundamental problem of time in quantum gravity and on some new results concerning the quantization of field theoretical reference frames.
Roberto Emparan (Barcelona) | Title: Quantum Gravity in Near-Extremal Black Holes | November 14, 2025
Recent developments have revealed that black holes near extremality exhibit large quantum fluctuations in their geometry, marking a controllable breakdown of semiclassical quantum field theory in curved spacetime. In this talk, I will discuss how these fluctuations can be revealed through scattering waves off the black hole. In particular, we find that extremely cold black holes become transparent to low-frequency light or gravitational radiation. These effects provide concrete signatures of quantum gravity at play in near-extremal regimes.
Washington Taylor (MIT) | Connecting the Calabi-Yau landscape and physics using the geometry of elliptic fibrations | November 21, 2025
Calabi-Yau manifolds have been used for over 30 years as a primary way of compactifying string theory to give semi-realistic models of physics in four dimensions. This talk describes recent progress in using the geometry of elliptic fibrations through the approach known as F-theory to better understand the physics of a broad class of nonperturbative string compactifications, to identify ways in which the Standard Model of particle physics arises naturally in this context, and to shed light on the structure of the largest known set of Calabi-Yau manifolds. In particular, the talk will describe a recent complete analysis the full set of 470 million toric hypersurface Calabi-Yau threefolds, of which over 99.99% have an elliptic or genus one fiber structure. This approach also helps understand the way in which all of these Calabi-Yaus are connected, and provides strong evidence that the set of such manifolds is finite. This talk describes recent work with Shing Yan Li and with Fatima Abbasi and Richard Nally, and upcoming work with Lara Anderson, James Gray, and Richard Nally.
