PIRSA:21110013

Wormholes in the partially disorder-averaged SYK model

Goto, K. (2021). Wormholes in the partially disorder-averaged SYK model. Perimeter Institute. https://pirsa.org/21110013

Goto, Kanato. Wormholes in the partially disorder-averaged SYK model. Perimeter Institute, Nov. 09, 2021, https://pirsa.org/21110013 

          @misc{ pirsa_PIRSA:21110013,
            doi = {10.48660/21110013},
            url = {https://pirsa.org/21110013},
            author = {Goto, Kanato},
            keywords = {Quantum Fields and Strings},
            language = {en},
            title = {Wormholes in the partially disorder-averaged SYK model},
            publisher = {Perimeter Institute},
            year = {2021},
            month = {nov},
            note = {PIRSA:21110013 see, \url{https://pirsa.org}}
          }

Kanato Goto

University of Tokyo

Talk number
PIRSA:21110013
Collection
Talk Type
Subject
Abstract

Recent studies revealed that wormhole geometries play a central role in understanding quantum gravity. After disorder-averaging over random couplings, Sachdev-Ye-Kitaev (SYK) model has a collective field description of wormhole saddles. A recent paper by Saad, Shenker, Stanford, and Yao studied the SYK model with fixed couplings and found that the wormhole saddles persist, but that new saddles called “half-wormholes” also appear in the path-integral. 

In this talk, we introduce a “partially disorder-averaged SYK model” and study how these half-wormholes emerge as we gradually fix the coupling constants. This model has a real parameter that smoothly interpolates between the ordinary totally disorder-averaged SYK model and the totally fixed-coupling model. For the large N effective description, in addition to the usual bi-local collective fields, we also introduce a new additional set of local collective fields. These local fields can be understood as the “half” of the bi-local collective fields, and they represent the half-wormholes in the totally fixed-coupling limit. We found that the large N saddles of these local fields vanish in the total-disorder-averaged limit, while they develop non-trivial profiles as we gradually fix the coupling constants. This illuminates how the half-wormhole saddles emerge in the SYK model with fixed couplings.