Perturbed Sachdev-Ye-Kitaev model: a polaron in the hyperbolic plane
Abstract
We study the SYK4 model with a weak SYK2 term of magnitude beyond the simplest perturbative limit considered previously. For intermediate values of the perturbation strength, J/N J/N, fluctuations of the Schwarzian mode are suppressed, and the SYK4 mean-field solution remains valid beyond the timescale t0 N/J up to t* J/2. Out-of-time-order correlation function displays at short time intervals exponential growth with maximal Lyapunov exponent 2π T, but its prefactor scales as T at low temperatures T ≤ .
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