2020/11/30 by Mikhail Khramtsov, Elena Lanina
Mathematics · Physics and Astronomy · #Algebraic structures and combinatorial models #Consistency (knowledge bases) #Extrapolation #Form factor (electronics) #Limit (mathematics) #Order (exchange) #Point (geometry) #Random Matrices and Applications #Saddle #Saddle point #Theoretical and Computational Physics #cond-mat.str-el #hep-th #quant-ph
paper · pdf · doi:10.1007/jhep03(2021)031
published as JHEP 03 (2021) 031 · 34+9 pages, 14 figures. v2: added reference, published version
openalex created_date 2020/11/09 · openalex publication_date 2021/03/01 · arxiv created 2021/03/11 · arxiv updated 2021/03/12 · openalex updated_date 2026/08/05
A bstract In this note we study the spectral form factor in the SYK model in large q limit at infinite temperature. We construct analytic solutions for the saddle point equations that describe the slope and the ramp regions of the spectral form factor time dependence. These saddle points are obtained by taking different approaches to the large q limit: the slope region is described by a replica-diagonal solution and the ramp region is described by a replica-nondiagonal solution. We find that the onset of the ramp behavior happens at the Thouless time of order q log q . We also evaluate the one-loop corrections to the slope and ramp solutions for late times, and study the transition from the slope to the ramp. We show this transition is accompanied by the breakdown of the perturbative 1 /q expansion, and that the Thouless time is defined by the consistency of extrapolation of this expansion to late times.