Chiral perturbation theory and nucleon-pion-state contaminations in lattice QCD

Abstract

Multi-particle states with additional pions are expected to be a non-negligible source of excited-state contamination in lattice simulations at the physical point. It is shown that baryon chiral perturbation theory can be employed to calculate the contamination due to two-particle nucleon-pion states in various nucleon observables. Leading order results are presented for the nucleon axial, tensor and scalar charge and three Mellin moments of parton distribution functions (quark momentum fraction, helicity and transversity moment). Taking into account phenomenological results for the charges and moments the impact of the nucleon-pion-states on lattice estimates for these observables can be estimated. The nucleon-pion-state contribution results in an overestimation of all charges and moments obtained with the plateau method. The overestimation is at the 5-10% level for source-sink separations of about 2 fm. The source-sink separations accessible in contemporary lattice simulations are found to be too small for chiral perturbation theory to be directly applicable.

32 pages, 12 figures, review article for the International Journal of Modern Physics. V2: Comment and five references added

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Cited by in corpus (10)

• FLAG Review 2021
• FLAG Review 2024
• Nucleon axial, scalar, and tensor charges using lattice QCD at the physical pion mass
• $N\pi$-state contamination in lattice calculations of the nucleon axial form factors
• Status of Lattice QCD Determination of Nucleon Form Factors and their Relevance for the Few-GeV Neutrino Program
• $N\pi$-states and the projection method for the nucleon axial and pseudoscalar form factors
• Excited states in nucleon structure calculations
• $N\pi$-state contamination in lattice calculations of the nucleon electromagnetic form factors
• Detailed analysis of excited state systematics in a lattice QCD calculation of $g_A$
• Light-quark mass dependence of the nucleon axial charge and pion-nucleon scattering phenomenology