String Theory seminar - Masanori Hanada Seminar

Abstract: How can we characterize the classical and quantum chaos? Typically, the sensitivity to small perturbations is regarded as the defining property. This characterization is reasonable for some cases, but fails in many cases. Even for classical systems, there is a subtlety when we relate them to quantum theory. For quantum chaos, the "universal" behavior of the energy spectrum is widely used, but it is not clear how it is related to the classical theory. In this talk we suggest other characterizations based on certain spectrum defined from two- and four-point functions. Along the way we see some "strongly" universal aspects of quantum gravitational systems.