Excited-state hadron masses using the stochastic LapH method

TL;DR

This paper advances lattice QCD calculations of excited hadron spectra by introducing a stochastic LapH method that efficiently handles multi-hadron operators and mixing, revealing challenges in extracting high-lying resonance energies.

Contribution

It introduces a stochastic LapH method for improved treatment of low-lying modes in lattice QCD, enabling better analysis of excited hadron states and operator mixing.

Findings

Feasibility of computing mixing between glueball and quark-antiquark operators.

Initial results indicate difficulties in extracting high-lying resonance energies with single-hadron operators.

Demonstration of the stochastic LapH method's effectiveness in complex operator analyses.

Abstract

Progress in computing the spectrum of excited baryons and mesons in lattice QCD is described. Large sets of spatially-extended hadron operators are used. The need for multi-hadron operators in addition to single-hadron operators is emphasized, necessitating the use of a new stochastic method of treating the low-lying modes of quark propagation which exploits Laplacian Heaviside quark-field smearing. A new glueball operator is tested and computing the mixing of this glueball operator with a quark-antiquark operator and multiple two-pion operators is shown to be feasible. Some of our initial results show warning signs about extracting high-lying resonance energies using only single-hadron operators.