Excited-state energies and scattering phase shifts from lattice QCD with the stochastic LapH method

TL;DR

This paper demonstrates a stochastic LapH method enabling the calculation of excited-state energies and meson-meson scattering phase shifts in lattice QCD on large lattices near physical pion masses.

Contribution

It introduces a stochastic approach using Laplacian Heaviside smearing to efficiently compute excited states and scattering phases on large lattice volumes.

Findings

Successful computation of excited-state energies.

Extraction of meson-meson scattering phase shifts.

Application on large lattices at near physical pion masses.

Abstract

Recent results in computing excited-state energies and meson-meson scattering phase shifts in lattice QCD are presented. A stochastic method of treating the low-lying modes of quark propagation that exploits Laplacian Heaviside quark-field smearing makes such studies possible now on large 32^3 x 256 and 48^3 x 128 lattices at near physical pion masses. Levels are identified using a variety of probe interpolating operators, which include both single-hadron and a large number of two-hadron operators.