Bosonic near-CFT$_1$ models from Fock-space fluxes

Abstract: We construct a family of near-CFT$_1$ models with a conserved U(1) charge, whose basic degrees of freedom are canonical bosons. The Sachdev-Ye-Kitaev (SYK) model -- the first microscopic model that realizes the near-CFT$_1$ dynamics -- is based on random $p$-local interactions among fermions. However, a bosonic near-CFT$_1$ model has remained elusive in the $p$-local approach because such constructions generally suffer from unwanted orderings at low temperatures. Our construction is based on a recent insight that near-CFT$_1$ dynamics can quite generally arise if we place a large amount of random fluxes in a many-body Fock space and $p$-locality is not essential. All such models are essentially solved by chord diagrams regardless of the nature of the underlying degrees of freedom. We further argue that such bosonic models do not suffer from energetic instablities or unwanted low-temperature orderings. For comparison we also consider a second class of charge-conserving models which are based on qubits. The thermodynamic scalings of these models are very similar to those of the double-scaled complex SYK model but are free of certain singularities the latter suffers from. We also show the level statistics of both models are described by random matrix theory universality down to very low energies.