QCD with two light dynamical chirally improved quarks: Mesons

TL;DR

This study computes the light and strange meson spectrum using lattice QCD with chirally improved quarks, analyzing excited states, mixing, and decay constants across multiple ensembles to enhance understanding of meson properties.

Contribution

It introduces an improved variational method with a diverse interpolator basis for more accurate meson spectrum extraction in lattice QCD with chirally improved quarks.

Findings

Determined meson masses including excited states and exotic channels.

Calculated the ratio of kaon to pion decay constants as 1.215(41).

Provided improved low-lying kaon spectrum results.

Abstract

We present results for the spectrum of light and strange mesons on configurations with two flavors of mass-degenerate Chirally Improved sea quarks. The calculations are performed on seven ensembles of lattice size 16^3x32 at three different gauge couplings and with pion masses ranging from 250 to 600 MeV. To reliably extract excited states, we use the variational method with an interpolator basis containing both gaussian and derivative quark sources. Both conventional and exotic channels up to spin 2 are considered. Strange quarks are treated within the partially quenched approximation. For kaons we investigate the mixing of interpolating fields corresponding to definite C-parity in the SU(3) limit. This enlarged basis allows for an improved determination of the low-lying kaon spectrum. In addition to masses we also extract the ratio of the pseudoscalar decay constants of the kaon and pion and obtain F_K/F_\pi=1.215(41). The results presented here include some ensembles from previous publications and the corresponding results supersede the previously published values.