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  • Open Access

Effects of flavor-mixings on charged kaon and pion parton distribution functions

Fabio L. Braghin1,* and Parada T. P. Hutauruk2,†

  • 1Instituto de Física, Federal University of Goiás, Avenida Esperança, s/n, 74690-900, Goiânia, GO, Brazil
  • 2International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM2), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8531, Japan

  • *Contact author: braghin@ufg.br
  • †Contact author: phutauruk@hiroshima-u.ac.jp
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Phys. Rev. D 114, 054046 – Published 23 September, 2026

DOI: https://doi.org/10.1103/2xjj-bfcf

Abstract

We investigate the charged kaon and pion parton distribution functions (PDFs) in the U(3) Nambu–Jona-Lasinio model, considering a novel flavor-mixing interaction arising from vacuum polarization that differs from the instanton-induced ’t Hooft interaction. In this work, the proper-time regularization scheme is employed, and, effectively, it might take quark confinement into account. The gap equations, the meson masses, and the meson-quark coupling constants are calculated in the presence of flavor-mixing interactions. The valence-quark distributions of the charged kaon and pion are calculated and compared with existing experimental data and Jefferson Lab Angular Momentum analysis results at scales μ2=4 and 27  GeV2. The strength of mixing effects on the PDFs is found to be proportional to the quark effective masses and their differences. We further find that the dominant flavor-mixing effects in the pion valence up-quark distribution at scales μ2=27 and 4  GeV2 are around x≃0.3 and x≃0.8, while for the kaon, the effects are shown at around x≃0.2 and x≃0.7. We also find similar strength of mixing effects on the PDFs at both scales μ2=4 and 27  GeV2; however, it certainly improves the pion and kaon PDFs.

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Phys. Rev. D 114, 054046– Published 23 September, 2026
  • Received 29 July 2026
  • Accepted 8 September 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

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