SP Seminar @ICTP Stasi Seminar Rm Tuesday 24 April at 11 am - A. ALTLAND

[CM Section]

Joint ICTP/SISSA Statistical Physics Seminar

Tuesday 24 April at 11:00 a.m.
Luigi Stasi Seminar Room, first floor, Leonardo Building

Alexander ALTLAND
THP Institute for Theoretical Physics, Univ. of Cologne, Germany

"Large Conformal Goldstone Mode Fluctuations in the SYK Model"

Abstract:
This talk addresses the low energy physics of the Sachdev-Ye-Kitaev
model, a paradigm of strongly interacting (Majorana) quantum matter.
A salient feature of this system is its exceptionally high degree of 
symmetry
under reparameterizations of physical time. At low energies this symmetry
is spontaneously broken and the ensuing infinite dimensional Goldstone
mode manifold takes strong influence on all physical observables. We will
discuss the effects of these fluctuations on the example of the so-called
out of time ordered correlation functions, diagnostic tools to describe both
manifestations of quantum chaos in the system and its conjectured duality
to an AdS2 gravitational bulk. While previous work predicts exponential
decay of these correlations in time our main finding is that at large 
time scales
non-perturbative Goldstone mode fluctuations generate a crossover to power
law behavior. This phenomenon must have ramifications in the physics of the
holographic bulk which, however, we do not understand at present.