Non-Gaussian disorder average in the Sachdev-Ye-Kitaev model

Abstract

We study the effect of the non-Gaussian average over the random couplings in a complex version of the celebrated Sachdev-Ye-Kitaev (SYK) model. Using a Polchinski-like equation and random tensor Gaussian universality, we show that the effect of this non-Gaussian averaging leads to a modification of the variance of the Gaussian distribution of couplings at leading order in N. We then derive the form of the effective action to all orders. An explicit computation of the modification of the variance in the case of a quartic perturbation is performed for both the complex SYK model mentioned above and the SYK generalization proposed in D. Gross and V. Rosenhaus [J. High Energy Phys. 02 (2017) 093]JHEPFG1029-847910.1007/JHEP02(2017)093.