Comparison of different source calculations in two-nucleon channel at large quark mass

TL;DR

This study compares exponential and wall source calculations to assess systematic errors from excited states in two-nucleon energy shifts at large quark mass, providing insights into methodological accuracy in lattice QCD.

Contribution

It introduces a comparative analysis of source calculation methods to evaluate excited state contamination in two-nucleon energy measurements at high quark mass.

Findings

Wall source signals are difficult to identify in plateau regions.

Systematic errors vary between source types and volume sizes.

Results inform better extraction of nuclear energies in lattice QCD.

Abstract

We investigate a systematic error coming from higher excited state contributions in the energy shift of light nucleus in the two-nucleon channel by comparing two different source calculations with the exponential and wall sources. Since it is hard to obtain a clear signal of the wall source correlation function in a plateau region, we employ a large quark mass as the pion mass is 0.8 GeV in quenched QCD. We discuss the systematic error in the spin-triplet channel of the two-nucleon system, and the volume dependence of the energy shift.