Static Potential and Local Color Fields in Unquenched Three-Dimensional Lattice QCD

TL;DR

This study demonstrates string breaking in unquenched (2+1)-dimensional lattice QCD by measuring the static potential and local color fields, showing potential saturation and field relaxation at large quark separations.

Contribution

It provides clear evidence of string breaking in unquenched 3D lattice QCD using Wilson loops and improved actions on coarse lattices, with implications for 4D QCD simulations.

Findings

Static potential saturates at twice the heavy-light meson mass.

Color-electric field strength approaches vacuum values at large separations.

Efficient simulation method on coarse lattices enables access to string breaking phenomena.

Abstract

String breaking by dynamical quarks in (2+1)-d lattice QCD is demonstrated in this project, by measuring the static potential and the local color-electric field strength between a heavy quark and antiquark pair at large separations. Simulations are done for unquenched SU(2) color with two flavors of staggered quarks. An improved gluon action is used which allows simulations to be done on coarse lattices, providing an extremely efficient means to access the quark separations and propagation times at which string breaking occurs. The static quark potential is extracted using only Wilson loop operators and hence no valence quarks are present in the trial states. Results give unambiguous evidence for string breaking as the static quark potential completely saturates at twice the heavy-light meson mass at large separations. It is also shown that the local color-electric field strength between the quark pair tends toward vacuum values at large separations. Implications of these results for unquenched simulations of QCD in 4-d are drawn.