Entanglement entropy in d+1 SU(N) gauge theory
Alexander Velytsky
TL;DR
This work analyzes entanglement entropy for subregions in SU(N) lattice gauge theories across dimensions using the replica trick and Migdal-Kadanoff approximations. It demonstrates a nonanalytic change in the RG flow of character-expansion coefficients governing the partition function in d>2, signaling a transition in the entanglement structure within the confinement phase and connecting the critical length scale to the finite-temperature transition scale. The exactly solvable d=1 case provides baseline behavior, while MK-based results in higher dimensions reveal a dimension- and N_c-dependent transition location, with caution about MK's limitations. The study suggests entanglement entropy as a diagnostic for confinement-related phase structure and encourages numerical verification, e.g., Monte Carlo simulations, and links to vortex-free-energy order parameters.
Abstract
We consider the entanglement entropy for a sub-system in d+1 dimensional SU(N) lattice gauge theory. The 1+1 gauge theory is treated exactly and shows trivial behavior. Gauge theories in higher dimensions are treated within Migdal-Kadanoff approximation. We consider the gauge theory in the confinement phase. We demonstrate the existence of a non-analytical change from the short distance to long distance form in the entanglement entropy in such systems (d>2) reminiscent of a phase transition. The transition is manifested in nontrivial change in the RG flow of the character expansion coefficients defining the partition function.
