Quantizing causal diamonds in gravity

• Rodrigo Andrade E Silva (Perimeter Institute for Theoretical Physics)

Room: PI/3-394 - Skyroom Abstract: When quantizing a gravitational system that admits a suitable gauge-fixing of time by surfaces of constant-mean-curvature, the reduced phase space can be obtained non-perturbatively and, for pure gravity, it is realized as the cotangent bundle of the space of conformal geometries of the Cauchy slice. I will delineate how to apply this approach to quantize causal diamonds in (2+1)-dimensions, with a non-positive cosmological constant, employing a fully non-perturbative, group-theoretic quantization scheme based on a BMS_3 group of symmetries.

Centralizers of quantum groups, orthogonal polynomials and link invariants

• Meri Zaimi (Perimeter Institute for Theoretical Physics)

Room: PI/3-394 - Skyroom Abstract: In this talk, I will discuss centralizers of the quantum groups associated to the Lie algebras S|N when acting on a tensor product of vector spaces, in the spirit of the Schur–Weyl duality. I will briefly explain how in some cases the centralizers can be described with the help of an algebra related to orthogonal polynomials, and I will discuss their diagrammatic interpretation in the context of link invariants and Chern–Simons theory, a topological quantum field theory.

Nonperturbative dynamics analytically and numerically

• Andrey Shkerin (Perimeter Institute for Theoretical Physics)

Room: PI/3-394 - Skyroom Abstract: I will outline my main research direction which deals with various nonperturbative phenomena in particle physics and cosmology. In particular, I will mention first order phase transitions from a thermal state, where new non-equilibrium features were uncovered that affect the real-time dynamics of the transition and can change its rate.

Bubbles of Anti-deSitter as black hole mimickers

• Suvendu Giri (Perimeter Institute for Theoretical Physics)

Room: PI/3-394 - Skyroom Abstract: The detection of gravitational waves by the Ligo-Virgo-Kagra collaboration, and the remarkable images produced by the EHT collaboration have opened new avenues into the study of highly compact objects in our universe. While observations suggest these objects are black holes, they don't rule out other possibilities. Black holes, however, create paradoxes that challenge well-established physical principles, leading to growing interest in horizonless ultra-compact objects — often called "black hole mimickers." To understand mimickers, we need concrete, well-motivated models that are both theoretically feasible and astrophysically relevant — something that's currently scarce. In this lightning talk, I will summarily present a class of mimickers called “Anti-deSitter black shells,” which provide a promising candidate model for further study.

Frontiers in Cosmic Ray Puzzles and Why They Matter

• Mohamad Shalaby (Perimeter Institute for Theoretical Physics)

Room: PI/3-394 - Skyroom In this brief presentation, I will highlight several cosmic ray puzzles that arise from discrepancies between incredibly precise new observations and models used to approximate the observed spectra and abundances of various cosmic ray species. These models rely on advanced numerical techniques, yet significant differences remain. I will conclude by outlining my efforts to address the main sources of these disagreements.