On the effect of excited states in lattice calculations of the nucleon axial charge

Abstract

Excited-state contamination is one of the dominant uncertainties in lattice calculations of the nucleon axial-charge, $g_A$. Recently published results in leading-order chiral perturbation theory (ChPT) predict the excited-state contamination to be independent of the nucleon interpolator and positive. However, empirical results from numerical lattice calculations show negative contamination (downward curvature), indicating that present-day calculations are not in the regime where the leading-order ChPT predictions apply. In this paper we show that, under plausible assumptions, one can reproduce the behavior of lattice correlators by taking into account final-state $N\pi$ interactions, in particular the effect of the Roper resonance, and by postulating a sign change in the infinite-volume $N\to N\pi$ axial-vector transition amplitude.

18 pages, 12 figures, v2: fixed minor typos and improved discussion, corrected description of another reference, included an additional volume in excited-state-contamination prediction (Fig 9)

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Cited by in corpus (17)

• FLAG Review 2019
• FLAG Review 2021
• Axial Vector Form Factors from Lattice QCD that Satisfy the PCAC Relation
• Systematic uncertainties in parton distribution functions from lattice QCD simulations at the physical point
• Precision Nucleon Charges and Form Factors Using 2+1-flavor Lattice QCD
• Nucleon axial structure from lattice QCD
• Towards grounding nuclear physics in QCD
• FLAG Review 2024
• Iso-vector axial form factors of the nucleon in two-flavour lattice QCD
• Nucleon axial, scalar, and tensor charges using lattice QCD at the physical pion mass
• Toward $N$ to $N\pi$ matrix elements from lattice QCD
• Multi-hadron-state contamination in nucleon observables from chiral perturbation theory
• Excited states in nucleon structure calculations
• Nucleon Mass with Highly Improved Staggered Quarks
• Prospects for a lattice calculation of the rare decay ${\Sigma }^{+}\to p{\ell }^{+}{\ell }^{-}$
• Excited-state effects in nucleon structure on the lattice using hybrid interpolators
• Nucleon form factors and couplings with $N_{\mathrm{f}}=2+1$ Wilson fermions