Scalar glueball and meson spectroscopy in unquenched lattice QCD with improved staggered quarks

TL;DR

This study explores scalar glueball and meson states in unquenched lattice QCD with improved staggered quarks, revealing insights into their masses and taste violations at different lattice spacings.

Contribution

It provides the first unquenched lattice QCD analysis of scalar glueball and meson states using improved staggered fermions, highlighting taste violations and decay effects.

Findings

Glueball mass similar to quenched results at finite lattice spacing

Significant taste violations observed in the scalar sector

Evidence suggests non-singlet meson is heavier than non-strange singlet meson

Abstract

We present results of an exploratory study of singlet scalar states in unquenched QCD using both glueball and meson operators. Results for non-singlet non-strange scalar mesons are also presented. We use Asqtad improved staggered fermions and gauge configurations generated by the MILC collaboration at lattice spacings of .12 and .09 fm. In this formulation, the glueball mass is not significantly different from the quenched value at finite lattice spacing. Significant taste violations are present in the scalar sector. At light quark masses, decay channels complicate the mass determinations. There is some evidence that the non-strange singlet meson lies below the non-singlet meson.