Full QCD Light Hadron Spectrum and Quark Masses: Final Results from CP-PACS

TL;DR

This paper reports final results from the CP-PACS collaboration on the light hadron spectrum and quark masses using two-flavor dynamical quarks, showing improved agreement with experimental data and reduced quark mass estimates compared to quenched QCD.

Contribution

The study provides the first comprehensive calculation of the light hadron spectrum and quark masses with two dynamical quark flavors, demonstrating the significance of sea quark effects.

Findings

Improved agreement of meson spectrum with experimental data.

Light quark masses are reduced by about 25% compared to quenched QCD.

Sea quark effects are crucial for accurate hadron spectrum predictions.

Abstract

We present the final results of the CP-PACS calculation of the light hadron spectrum and quark masses with two flavors of dynamical quarks. Simulations are made with a renormalization-group improved gauge action and a mean-field improved clover quark action for sea quark masses corresponding to $m_{\rm PS}/m_{\rm V} \approx 0.8$--0.6 and the lattice spacing $a=0.22$--0.11 fm. For the meson spectrum in the continuum limit a clearly improved agreement with experiment is observed compared to the quenched case, demonstrating the importance of sea quark effects. For light quark masses we obtain $m_{ud}^{\bar{MS}}(2GeV)=3.44^{+0.14}_{-0.22}$ MeV and $m_s^{\bar{MS}}(2GeV)=88^{+4}_{-6}$ MeV ($K$-input) and $m_s^{\bar{MS}}(2GeV)=90^{+5}_{-11}$ MeV ($\phi$-input), which are reduced by about 25% compared to the values in quenched QCD.