The QCD spectrum with three quark flavors

TL;DR

This study compares the hadron spectrum in lattice QCD with three dynamical quark flavors to quenched simulations, showing improved agreement with experimental data when sea quarks are included.

Contribution

First lattice QCD calculation with three dynamical flavors using improved actions, providing insights into sea quark effects on the spectrum and static potential.

Findings

Full QCD spectrum aligns better with experiments.

Sea quarks influence the static quark potential.

Observation of meson decay coupling on the lattice.

Abstract

We present results from a lattice hadron spectrum calculation using three flavors of dynamical quarks - two light and one strange, and quenched simulations for comparison. These simulations were done using a one-loop Symanzik improved gauge action and an improved Kogut-Susskind quark action. The lattice spacings, and hence also the physical volumes, were tuned to be the same in all the runs to better expose differences due to flavor number. Lattice spacings were tuned using the static quark potential, so as a byproduct we obtain updated results for the effect of sea quarks on the static quark potential. We find indications that the full QCD meson spectrum is in better agreement with experiment than the quenched spectrum. For the 0++ (a0) meson we see a coupling to two pseudoscalar mesons, or a meson decay on the lattice.