HET Journal club: Juan Pedraza

Speaker: Juan Pedraza

Title: Chaotic strings in AdS/CFT

Abstract: Holographic theories with classical gravity duals are maximally chaotic, i.e. they saturate the universal bound on the rate of growth of chaos. It is interesting to ask weather this property is true only for leading large N correlators or if it can show up elsewhere. In this letter we consider the simplest setup to tackle this question: a Brownian particle coupled to a thermal ensemble. We find that the four-point out-of-time-order correlator that diagnoses chaos initially grows at an exponential rate that saturates chaos bound, i.e. with a Lyapunov exponent λL=2π/β. However, the scrambling time is parametrically smaller than for plasma excitations, t∗∼βlogλ−−√ instead of t∗∼βlogN2. Our result shows that, at least in certain cases, maximal chaos can be attained in the probe sector without the explicit need of gravitational degrees of freedom.