April 01, 2025

Exploring CPT-Invariant Path Integrals in 3D Quantum Gravity

SOKENDAI Student Dispatch Program program year: 2024

CHOU, Chien-Yu

Particle and Nuclear Physics

 

A Mirror Universe: CPT Symmetry and the Big Bang
A Mirror Universe: CPT Symmetry and the Big Bang

This image represents a possible explanation for the Big Bang based on CPT symmetry. The two mirrored shapes suggest that our universe has a symmetric counterpart extending backward in time. Instead of a singular beginning, the Big Bang could be a transition between two connected universes, following the fundamental symmetries of physics.

My research explores the CPT-invariant formulation of path integrals in 3D quantum gravity, particularly in de Sitter (dS) space, which plays a crucial role in understanding the nature of spacetime at the quantum level. Unlike Anti-de Sitter (AdS) space, which has a well-defined holographic dual, de Sitter space presents unique challenges in defining quantum states. To address this, I investigate how CPT symmetry constrains boundary conditions and saddle points in the gravitational path integral. This study builds on the Chern-Simons formulation of 3D gravity, which provides a natural framework for describing quantum gravity in a topological setting.

During my research stay at the University of Edinburgh, I worked closely with Prof. Turok and colleagues to explore the role of complex saddle points in the Einstein-Hilbert action. Additionally, I analyzed the CPT invariance of the Chern-Simons action and its implications for de Sitter quantum gravity. While this research is ongoing, we have established a long-term collaboration to further develop a CPT-invariant path integral formulation. Our future work will explore the role of modular structures in the de Sitter partition function, with potential applications in quantum cosmology, topological quantum field theory, and nonperturbative quantum gravity.

Period of Stay

Date of Departure: 2024/11/30
Date of Return: 2025/2/28

Country and/or City

UK

Visiting Institute, Host, or Meeting

University of Edinburgh, Hosted by Prof. Neil Turok

What you learned and achieved during the visit

My research stay at the University of Edinburgh provided invaluable opportunities to collaborate with Prof. Turok and his research team, deepening my understanding of CPT-invariant quantum gravity. Through discussions and analysis, I explored the role of complex saddle points and Chern-Simons theory in de Sitter space. This experience helped establish a long-term collaboration to further investigate modular structures in the gravitational path integral and nonperturbative quantum gravity.

Department of Particle and Nuclear Physics, CHOU, Chien-Yu

     

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