Toward the excited meson spectrum of dynamical QCD

TL;DR

This paper advances the understanding of the excited meson spectrum in dynamical QCD by employing novel operator construction and variational techniques on anisotropic lattices, successfully identifying high-spin and exotic states with high precision.

Contribution

It introduces a new quark-field construction algorithm and a comprehensive variational basis to reliably determine the continuum spin of excited meson states in lattice QCD.

Findings

Resolved high-spin and exotic meson states, including spin-four states.

Achieved high statistical precision (~1%) for excited state spectra.

First lattice QCD calculation of spin-four meson states.

Abstract

We present a detailed description of the extraction of the highly excited isovector meson spectrum on dynamical anisotropic lattices using a new quark-field construction algorithm and a large variational basis of operators. With careful operator construction, the combination of these techniques is used to identify the continuum spin of extracted states reliably, overcoming the reduced rotational symmetry of the cubic lattice. Excited states, states with exotic quantum numbers (0+-, 1-+ and 2+-) and states of high spin are resolved, including, for the first time in a lattice QCD calculation, spin-four states. The determinations of the spectrum of isovector mesons and kaons are performed on dynamical lattices with two volumes and with pion masses down to ~ 400 MeV, with statistical precision typically at or below 1% even for highly excited states.