2024/03/01(Fri) 11:00 -12:15 五樓第一會議室 5F, 1st Meeting Room
Title
Free theories in QFT and the initial state of the Universe
Abstract
In QFT, positive definiteness, gauge invariance and renormalizability of gauge theories can be appreciated better by starting with the free theory Hamiltonian. Interactions can be introduced via similarity transformation of the canonical field momentums with the corresponding Chern-Simon term. Instead of the ordinary symplectic structure, it is the SL(3R) group structure that provides the more restrictive quantization structures for gravitation. The Cotton-York tensor density is an analogy to the magnetic potential in Yang-Mills theories, but gravitation can not be Yang-Mill theories, since it is the metric variable that will provide micro-causality in the theory, not the connection variables. Besides, one d.o.f in the metric can be employed to serve as a time(intrinsic) variable in the theory. When fermionic matter fields are incorporated, Lorentzian signature spacetimes forbid the establishment of consistent spin structure, this sheds light to construct an unique initial state of the Universe with Euclidean signature which satisfies the Hawking-Hartle no boundary proposal and Penrose's Weyl curvature conjecture. Scale invariant primordial gravitational wave fluctuations will provide a smoking gun test of the Intrinsic Time Geometrodynamics quantum gravity program.
Language
演講語言 (Language): in English