Nucleon Momentum Fraction, Helicity and Transversity from 2+1-flavor Lattice QCD

Abstract

High statistics results for the isovector momentum fraction, $⟨x{⟩}_{u-d}$, helicity moment, $⟨x{⟩}_{\Delta u-\Delta d}$, and the transversity moment, $⟨x{⟩}_{\delta u-\delta d}$, of the nucleon are presented using seven ensembles of gauge configurations generated by the JLab/W&M/LANL/MIT collaborations using $2+1$-flavors of dynamical Wilson-clover quarks. Attention is given to understanding and controlling the contributions of excited states. The final results are obtained using a simultaneous fit in the lattice spacing $a$, pion mass $M_{\pi }$ and the finite volume parameter $M_{\pi }L$ keeping leading order corrections. The data show no significant dependence on the lattice spacing and some evidence for finite-volume corrections. The main variation is with $M_{\pi }$, whose magnitude depends on the mass gap of the first excited state used in the analysis. Our final results, in the $\overline{\mathrm{MS}}$ scheme at 2 GeV, are $⟨x{⟩}_{u-d}=0.160(16)(20)$, $⟨x{⟩}_{\Delta u-\Delta d}=0.192(13)(20)$ and $⟨x{⟩}_{\delta u-\delta d}=0.215(17)(20)$, where the first error is the overall analysis uncertainty assuming excited-state contributions have been removed, and the second is an additional systematic uncertainty due to possible residual excited-state contributions. These results are consistent with other recent lattice calculations and phenomenological global fit values.

arXiv comment28 pages, 11 figures, 12 tables. arXiv admin note: text overlap with arXiv:2005.13779

References in corpus (43)

• Parton distributions from high-precision collider data
• New parton distribution functions from a global analysis of quantum chromodynamics
• Parton distributions in the LHC era: MMHT 2014 PDFs
• Generalized Parton Distributions
• The Chroma Software System for Lattice QCD
• FLAG Review 2019
• New CTEQ global analysis of quantum chromodynamics with high-precision data from the LHC
• Analytic Smearing of SU(3) Link Variables in Lattice QCD
• Solving Lattice QCD systems of equations using mixed precision solvers on GPUs
• Non-perturbative O(a) improvement of lattice QCD
• Parton Distribution Functions, ${\alpha }_s$ and Heavy-Quark Masses for LHC Run II
• Extraction of Spin-Dependent Parton Densities and Their Uncertainties
• A first unbiased global determination of polarized PDFs and their uncertainties
• Physics Opportunities with the 12 GeV Upgrade at Jefferson Lab
• Constraints on large-$x$ parton distributions from new weak boson production and deep-inelastic scattering data
• Global Analysis of Helicity Parton Densities and Their Uncertainties
• Nucleon structure from mixed action calculations using 2+1 flavors of asqtad sea and domain wall valence fermions
• Parton distributions and lattice QCD calculations: a community white paper
• Effective noise reduction techniques for disconnected loops in Lattice QCD
• First simultaneous extraction of spin-dependent parton distributions and fragmentation functions from a global QCD analysis
• A new class of variance reduction techniques using lattice symmetries
• A guide to light-cone PDFs from Lattice QCD: an overview of approaches, techniques and results
• Proton Mass Decomposition from the QCD Energy Momentum Tensor
• Adaptive multigrid algorithm for the lattice Wilson-Dirac operator
• Axial, Scalar and Tensor Charges of the Nucleon from 2+1+1-flavor Lattice QCD
• Isovector Charges of the Nucleon from 2+1+1-flavor Lattice QCD
• Complete flavor decomposition of the spin and momentum fraction of the proton using lattice QCD simulations at physical pion mass
• Polarized and Unpolarized Nucleon Structure Functions from Lattice QCD
• The nucleon spin and momentum decomposition using lattice QCD simulations
• Nucleon Charges and Electromagnetic Form Factors from 2+1+1-Flavor Lattice QCD
• Axial Vector Form Factors from Lattice QCD that Satisfy the PCAC Relation
• Nucleon isovector structure functions in (2+1)-flavor QCD with domain wall fermions
• Moments of nucleon generalized parton distributions from lattice QCD simulations at physical pion mass
• Nucleon Structure from Lattice QCD Using a Nearly Physical Pion Mass
• Nucleon Transverse Momentum-dependent Parton Distributions in Lattice QCD: Renormalization Patterns and Discretization Effects
• Nucleon isovector charges and twist-2 matrix elements with $N_f=2+1$ dynamical Wilson quarks
• Isovector charges of the nucleon from 2+1-flavor QCD with clover fermions
• Controlling Excited-State Contamination in Nucleon Matrix Elements
• The moment $⟨x{⟩}_{u-d}$ of the nucleon from $N_f=2$ lattice QCD down to nearly physical quark masses
• Nucleon generalized form factors from two-flavor lattice QCD
• Three loop anomalous dimension of the second moment of the transversity operator in the MSbar and RI' schemes
• Renormalization of local quark-bilinear operators for Nf=3 flavors of SLiNC fermions
• Moments of nucleon isovector structure functions in $2+1+1$-flavor QCD

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