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Regular version of the site

Article

Sachdev-Ye-Kitaev model with quadratic perturbations: the route to a non-Fermi-liquid

Physical Review Letters. 2018. Vol. 121. No. 23. P. 236601-1-236601-5.

We study stability of the SYK4 model with a large but finite number of fermions N with respect to a perturbation, quadratic in fermionic operators. We develop analytic perturbation theory in the amplitude of the SYK2 perturbation and demonstrate stability of the SYK4 infra-red asymptotic behavior characterized by a Green function G(tau) = 1/tau^{3/2}, with respect to weak perturbation. This result is supported by exact numerical diagornalization. Our results open the way to build a theory of non-Fermi-liquid states of strongly interacting fermions.