Informal seminar
日時：7月25日（火）15:30〜
場所：F216 (第8講義室)
Speaker: Hikaru KAWAI（National Taiwan University)
Title: "Quantum Phase Transitions and Solving the Naturalness Problem in Generalized Field Theories."
Abstract: In ordinary statistical mechanics, the extensive parameters (such as total volume and total energy) are more fundamental than the intensive parameters (such as temperature and pressure) in the sense that the latter are determined a posteriori by the former in the large volume limit. Furthermore, in a finite region of the extensive parameter space, the corresponding intensive parameters are automatically fixed to the first-order phase transition point.
Analogously, in conventional quantum field theory, coupling constants (including masses) in the path integral correspond to intensive parameters in the partition function of the canonical formulation. Therefore, it is natural to expect that in a more fundamental formulation of quantum field theory, coupling constants are dynamically fixed a posteriori in the large-volume limit, just as the intensive parameter in statistical mechanics.
In generalized field theories, we argue that an automatic fine-tuning is realized in which the coupling constant is fixed at the quantum phase transition point at zero temperature. This occurs even if the transition is of higher order due to the Lorentzian nature of the path integral.
This can be the basis for solving the naturalness problem.