Variance reduction in lattice QCD observables via normalizing flows
This work addresses the problem of variance reduction in lattice QCD observables for physicists working in the field of quantum chromodynamics.
This work tackled the problem of variance reduction in lattice QCD observables and achieved a variance reduction by factors of 10-60 in glueball correlation functions and gluonic matrix elements. The result demonstrates computational advantages and is approximately independent of the lattice volume.
Normalizing flows can be used to construct unbiased, reduced-variance estimators for lattice field theory observables that are defined by a derivative with respect to action parameters. This work implements the approach for observables involving gluonic operator insertions in the SU(3) Yang-Mills theory and two-flavor Quantum Chromodynamics (QCD) in four space-time dimensions. Variance reduction by factors of $10$-$60$ is achieved in glueball correlation functions and in gluonic matrix elements related to hadron structure, with demonstrated computational advantages. The observed variance reduction is found to be approximately independent of the lattice volume, so that volume transfer can be utilized to minimize training costs.