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Pion valence structure at intermediate x in the residual-field approach

Joseph Maerovitz and Misak Sargsian

Christopher Leon

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Phys. Rev. C 114, 045209 – Published 28 October, 2026

DOI: https://doi.org/10.1103/tsgs-hj99

Abstract

We calculate the valence parton distribution function (PDF) of pion within the theoretical approach based on spectral function representation of valence quarks in the pion. In this approach we assume that the soft partonic structure of pion is defined by the valence qq¯ cluster, consisting of current quarks, embedded in the residual field of the pion. The valence PDF is calculated using phenomenological light-front wave functions for the qq¯ cluster and the residual field. Our result indicates that the peak position of the x weighted valence PDF (xPDF) depends on parameters characterizing the virtuality of the valence quark cluster and the mass of the residual system. Magnitudes of these parameters are obtained by fitting to the height and the peak position of empirical pion xPDF evaluated at starting Q0. They indicate that unlike the nucleon case, very little residual mass is needed to describe existing pion PDFs at intermediate x. They also indicate that the qq¯ cluster is highly virtual and on average the interacting quark carries almost all of the momentum of the qq¯ cluster. This picture is consistent with the dominance of the Feynman mechanism leaving little room for the hard component in the PDF and practically describing ≈(1−x) behavior observed recently at x→1 limit. Our nontrivial observation is that the height and the peak position of xPDF define the analytic behavior of valence PDF at x→1 limit.

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Outline

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Phys. Rev. C 114, 045209– Published 28 October, 2026
  • Received 18 March 2026
  • Revised 12 August 2026
  • Accepted 29 September 2026
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