Lattice QCD Beyond Ground States

TL;DR

This paper explores black box methods for extracting excited-state energies in lattice QCD, demonstrating their effectiveness and consistency with traditional techniques without complex operator construction.

Contribution

It introduces and evaluates the multi-effective mass black box method for lattice QCD, showing its ability to extract multiple states from single correlators.

Findings

Black box methods are effective for excited-state energy extraction.

Multi-effective mass method shows good consistency with traditional approaches.

The approach simplifies the process without complex operator construction.

Abstract

In this work, we apply black box methods (methods not requiring input) to find excited-state energies. A variety of such methods for lattice QCD were introduced at the 3rd iteration of the numerical workshop series. We first review a selection of approaches that have been used in lattice calculations to determine multiple energy states: multiple correlator fits, the variational method and Bayesian fitting. In the second half, we will focus on a black box method, the multi-effective mass. We demonstrate the approach on anisotropic lattice data, extracting multiple states from single correlators. Without complicated operator construction or specialized fitting programs, the black box method shows good consistency with the traditional approaches.