8 research outputs found
Calculation Of Gluon Pdf In The Nucleon Using Pseudo-Pdf Formalism With Wilson Flow Technique In LQCD
A comprehensive study of the gluonic content in the nucleon from a first principles lattice quantum chromodynamics calculation is presented. The unpolarized gluonic distribution in the nucleon is calculated using the pseudo-PDF framework on the lattice. First, the spectral analyses of the low-lying states in the nucleon, as well as in the delta are performed on the lattice, identifying baryons states with hybrid characteristics, in which the gluons play a manifestly structural role, and determining a set of operators which have significant overlaps onto the ground state of the nucleon. Techniques such as distillation for smearing the quark fields, momentum smearing to achieve a better signal at the higher momenta, the gradient flow technique for suppressing the gauge fluctuations, and the solution of the summed generalized eigenvalue problem employing a set of operators determined by the nucleon spectral analysis are implemented to calculate the gluonic matrix elements. A combination of these techniques provides the most precise lattice determination of the gluonic distribution in the nucleon to date. Short distance factorization provides the perturbative matching kernel which, in turn, allows one to calculate the gluon Ioffe-time distribution in the MS scheme at μ = 2 GeV. To accomplish this task, a parametrization in terms of Jacobi polynomials is used in an approximation in which the mixing with the quark singlet sector is neglected. Finally, the results are compared with the phenomenological determinations
Gluon helicity distribution in the nucleon from lattice QCD and machine learning
We present the first lattice QCD determination of the light-cone gluon
helicity correlation parton distribution function (PDF) with numerical evidence
toward disfavoring negative gluon polarization in the nucleon. We present a
solution for eliminating an inevitable contamination term that dominates the
Euclidean correlations and makes determining gluon helicity PDF unfeasible. The
proposed synergy between lattice QCD and artificial intelligence offers a
superior platform to alleviate the defining challenge of extracting quark and
gluon PDFs from the lattice data that are available in a limited domain due to
a finite range of accessible hadron momenta. We suggest a systematically
improvable method to extract PDFs from the lattice data, independent of
inadequate parametrizations. The result of the gluon helicity will improve our
understanding of the role of spin in the strong interaction and the nucleon
spin structure.Comment: Phys. Rev. D. accepted version, 10 pages & 11 figure
Toward the Determination of the Gluon Helicity Distribution in the Nucleon from Lattice Quantum Chromodynamics
We present the first exploratory lattice quantum chromodynamics (QCD) calculation of the polarized gluon Ioffe-time pseudodistribution in the nucleon. The Ioffe-time pseudodistribution provides a frame-independent and gauge-invariant framework to determine the gluon helicity in the nucleon from first principles. We employ a high-statistics computation using a 323 × 64 lattice ensemble characterized by a 358 MeV pion mass and a 0.094 fm lattice spacing. We establish the pseudodistribution approach as a feasible method to address the proton spin puzzle with successive improvements in statistical and systematic uncertainties anticipated in the future. Within the statistical precision of our data, we find a good comparison between the lattice determined polarized gluon Ioffe-time distribution and the corresponding expectations from the state-of-the-art global analyses. We find a hint for a nonzero gluon spin contribution to the proton spin from the model-independent extraction of the gluon helicity pseudodistribution over a range of Ioffe-time, ν ≲ 9
Unpolarized Gluon Distribution in the Nucleon From Lattice Quantum Chromodynamics
In this study, we present a determination of the unpolarized gluon Ioffe-time distribution in the nucleon from a first principles lattice quantum chromodynamics calculation. We carry out the lattice calculation on a 323 × 64 ensemble with a pion mass of 358 MeV and lattice spacing of 0.094 fm. We construct the nucleon interpolating fields using the distillation technique, flow the gauge fields using the gradient flow, and solve the summed generalized eigenvalue problem to determine the gluonic matrix elements. Combining these techniques allows us to provide a statistically well-controlled Ioffe-time distribution and unpolarized gluon parton distribution function. We obtain the flow time independent reduced Ioffe-time pseudodistribution and calculate the light-cone Ioffe-time distribution and unpolarized gluon distribution function in the MS scheme at μ = 2  GeV, neglecting the mixing of the gluon operator with the quark singlet sector. Finally, we compare our results to phenomenological determinations
Towards the determination of the gluon helicity distribution in the nucleon from lattice quantum chromodynamics
We present the first exploratory lattice quantum chromodynamics (QCD) calculation of the polarized gluon Ioffe-time pseudo-distribution in the nucleon. The Ioffe-time pseudo-distribution provides a frame-independent and gauge-invariant framework to determine the gluon helicity in the nucleon from first principles. We employ a high-statistics computation using a lattice ensemble characterized by a MeV pion mass and a fm lattice spacing. We establish the pseudo-distribution approach as a feasible method to address the proton spin puzzle with successive improvements in statistical and systematic uncertainties anticipated in the future. Within the statistical precision of our data, we find a good comparison between the lattice determined polarized gluon Ioffe-time distribution and the corresponding expectations from the state-of-the-art global analyses. We find a hint for a nonzero gluon spin contribution to the proton spin from the model-independent extraction of the gluon helicity pseudo-distribution over a range of Ioffe-time,
Towards the determination of the gluon helicity distribution in the nucleon from lattice quantum chromodynamics
We present the first exploratory lattice quantum chromodynamics (QCD) calculation of the polarized gluon Ioffe-time pseudo-distribution in the nucleon. The Ioffe-time pseudo-distribution provides a frame-independent and gauge-invariant framework to determine the gluon helicity in the nucleon from first principles. We employ a high-statistics computation using a lattice ensemble characterized by a MeV pion mass and a fm lattice spacing. We establish the pseudo-distribution approach as a feasible method to address the proton spin puzzle with successive improvements in statistical and systematic uncertainties anticipated in the future. Within the statistical precision of our data, we find a good comparison between the lattice determined polarized gluon Ioffe-time distribution and the corresponding expectations from the state-of-the-art global analyses. We find a hint for a nonzero gluon spin contribution to the proton spin from the model-independent extraction of the gluon helicity pseudo-distribution over a range of Ioffe-time,
Unpolarized gluon distribution in the nucleon from lattice quantum chromodynamics
International audienceIn this study, we present a determination of the unpolarized gluon Ioffe-time distribution in the nucleon from a first principles lattice quantum chromodynamics calculation. We carry out the lattice calculation on a 323×64 ensemble with a pion mass of 358 MeV and lattice spacing of 0.094 fm. We construct the nucleon interpolating fields using the distillation technique, flow the gauge fields using the gradient flow, and solve the summed generalized eigenvalue problem to determine the gluonic matrix elements. Combining these techniques allows us to provide a statistically well-controlled Ioffe-time distribution and unpolarized gluon parton distribution function. We obtain the flow time independent reduced Ioffe-time pseudodistribution and calculate the light-cone Ioffe-time distribution and unpolarized gluon distribution function in the MS¯ scheme at μ=2  GeV, neglecting the mixing of the gluon operator with the quark singlet sector. Finally, we compare our results to phenomenological determinations