Report
Leading-twist proton parton distribution amplitude from scalar and axial-vector diquark correlations
| Title: | Leading-twist proton parton distribution amplitude from scalar and axial-vector diquark correlations |
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| Authors: | Almeida-Zamora, B., Albino, L., Mezrag, C., Segovia, J. |
| Publication Year: | 2026 |
| Collection: | High Energy Physics - Phenomenology High Energy Physics - Experiment High Energy Physics - Lattice Nuclear Experiment Nuclear Theory |
| Subject Terms: | High Energy Physics - Phenomenology, High Energy Physics - Experiment, High Energy Physics - Lattice, Nuclear Experiment, Nuclear Theory |
| Description: | We compute the leading-twist proton parton distribution amplitude (PDA) using algebraic representations of the nucleon Faddeev wave function inspired by perturbation-theory integral representations. The PDA is obtained from a light-front projection of the covariant quark--diquark Faddeev amplitude and analysed in terms of its scalar- and axial-vector-diquark components. We derive analytic expressions for the corresponding diquark distribution amplitudes and their contributions to the proton PDA. The resulting distribution is broad and concave, with its maximum $(x_1,x_2,x_3)\approx(0.55,0.20,0.25)$ displaced from the symmetric configuration $(1/3,1/3,1/3)$, which corresponds to the maximum of the perturbative-QCD asymptotic form. Scalar-diquark correlations generate a strong asymmetry in the longitudinal momentum distribution, whereas axial-vector correlations redistribute momentum among the valence quarks and significantly reduce this asymmetry. We calculate low-order Mellin moments and obtain a compact parametrisation of the proton PDA at the hadronic scale, $μ_0=0.51\,\mathrm{GeV}$. We then perform the leading-order QCD evolution of its normalized shape to $μ=2\,\mathrm{GeV}$, finding that evolution reduces the momentum asymmetry while preserving a clear imprint of the non-perturbative quark--diquark correlations. The results provide insight into the role of such correlations in shaping the proton light-front structure and furnish non-perturbative input for studies of hard exclusive baryonic processes. 24 pages, 9 figures, 3 tables |
| Document Type: | Working Paper |
| DOI: | 10.48550/arXiv.2610.22994 |
| Access URL: | https://arxiv.org/abs/2610.22994 |
| Accession Number: | edsarx.2610.22994 |
| Database: | arXiv |
| DOI: | 10.48550/arXiv.2610.22994 |
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