Disconnected contributions to the spin of the nucleon

Abstract

The spin decomposition of the proton is a long-standing topic of much interest in hadronic physics. Lattice QCD has had much success in calculating the connected contributions to the quark spin. However, complete calculations, which necessarily involve gluonic and strange-quark contributions, still present some challenges. These "disconnected" contributions typically involve small signals hidden against large statistical backgrounds and rely on computationally intensive stochastic techniques. In this work we demonstrate how a Feynman-Hellmann approach may be used to calculate such quantities, by measuring shifts in the proton energy arising from artificial modifications to the QCD action. We find a statistically significant non-zero result for the disconnected quark spin contribution to the proton of about -5% at a pion mass of 470 MeV.

References in corpus (28)

• The Chroma Software System for Lattice QCD
• The Spin Structure of the Nucleon
• The theory and phenomenology of polarized deep inelastic scattering
• The Deuteron Spin-dependent Structure Function g1d and its First Moment
• Nucleon structure from mixed action calculations using 2+1 flavors of asqtad sea and domain wall valence fermions
• The Spin Structure of the Proton
• The Spin Structure of the Nucleon
• Flavour blindness and patterns of flavour symmetry breaking in lattice simulations of up, down and strange quarks
• The nucleon axial charge from lattice QCD with controlled errors
• Nucleon Charges and Electromagnetic Form Factors from 2+1+1-Flavor Lattice QCD
• Nucleon form factors and moments of generalized parton distributions using $N_f=2+1+1$ twisted mass fermions
• Interplay of Spin and Orbital Angular Momentum in the Proton
• Quark mass dependence of hadron masses from lattice QCD
• Tuning the strange quark mass in lattice simulations
• Strangeness Contribution to the Proton Spin from Lattice QCD
• Strange quark contributions to nucleon mass and spin from lattice QCD
• Disconnected quark loop contributions to nucleon observables in lattice QCD
• A Lattice Study of Quark and Glue Momenta and Angular Momenta in the Nucleon
• High-precision calculation of the strange nucleon electromagnetic form factors
• Resolution of the Proton Spin Problem
• Exploring strange nucleon form factors on the lattice
• A Lattice Study of the Glue in the Nucleon
• Variational Approach to the Calculation of gA
• A Feynman-Hellmann approach to the spin structure of hadrons
• Precision Study of Excited State Effects in Nucleon Matrix Elements
• Renormalization of local quark-bilinear operators for Nf=3 flavors of SLiNC fermions
• Flavour singlet physics in lattice QCD with background fields
• A novel approach to nonperturbative renormalization of singlet and nonsinglet lattice operators

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• FLAG Review 2019
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• Updated Lattice Results for Parton Distributions
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• Nucleon axial form factors using lattice QCD simulations with a physical value of the pion mass
• Quantum Simulation of Quantum Field Theory in the Light-Front Formulation
• Up, down, and strange nucleon axial form factors from lattice QCD
• Proton-proton fusion and tritium $\beta$-decay from lattice quantum chromodynamics
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• FLAG Review 2024
• On the Feynman-Hellmann Theorem in Quantum Field Theory and the Calculation of Matrix Elements
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• Lattice QCD evaluation of the Compton amplitude employing the Feynman-Hellmann theorem
• An accurate calculation of the nucleon axial charge with lattice QCD
• Strange and Charm Quark Spins from Anomalous Ward Identity
• Generalised parton distributions from the off-forward Compton amplitude in lattice QCD
• The Role of Nucleon Strangeness in Supernova Explosions
• Evolution Equations for Connected and Disconnected Sea Parton Distributions
• Lattice QCD Inputs for Nuclear Double Beta Decay
• Constraining beyond the Standard Model nucleon isovector charges
• A Euclidean bridge to the relativistic constituent quark model
• Detailed analysis of excited state systematics in a lattice QCD calculation of $g_A$
• Moments and power corrections of longitudinal and transverse proton structure functions from lattice QCD
• Finite volume corrections to forward Compton scattering off the nucleon
• Nucleon in a periodic magnetic field: Finite-volume aspects
• Feynman--Hellmann approach to transition matrix elements and quasi-degenerate energy states
• Mapping Parton Distributions of Hadrons with Lattice QCD
• Hadron Structure and Spectrum from the Lattice
• Gross-Llewellyn Smith sum rule from lattice QCD
• New Physics Searches from Nucleon Matrix Elements in Lattice QCD
• Oscillation-Independent Probes of Neutrino Non-Standard Interactions from Supernovae