Toward a resolution of the NN controversy

TL;DR

This paper investigates discrepancies in lattice QCD calculations of two-nucleon interactions by examining operator choices and their effects on spectral extraction, aiming to resolve ongoing methodological controversies.

Contribution

It introduces a systematic analysis of operator effects on spectral results in lattice QCD and compares theoretical expectations with preliminary lattice data.

Findings

Operator choice significantly impacts spectral results

Finite volume EFT provides expectations for spectral variations

Preliminary lattice results show operator-dependent differences

Abstract

Lattice QCD calculations of two-nucleon interactions have been underway for about a decade, but still haven't reached the pion mass regime necessary for matching onto effective field theories and extrapolating to the physical point. Furthermore, results from different methods, including the use of the Luscher formalism with different types of operators, as well as the HALQCD potential method, do not agree even qualitatively at very heavy pion mass. We investigate the role that different operators employed in the literature may play on the extraction of spectra for use within the Luscher method. We first explore expectations from Effective Field Theory solved within a finite volume, for which the exact spectrum may be computed given different physical scenarios. We then present preliminary lattice QCD results for two-nucleon spectra calculated using different operators on a common lattice ensemble.