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Mechanical form factors and densities of nonrelativistic fermions

Adam Freese*

  • *Contact author: afreese@jlab.org
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Phys. Rev. D 112, 034037 – Published 29 August, 2025

DOI: https://doi.org/10.1103/k3hd-3lqv

Abstract

The hadron physics community has been actively debating the interpretation of so-called mechanical properties of hadrons. Nonrelativistic quantum-mechanical systems like the hydrogen atom have been appealed to in these debates as analogies. Since such appeals are likely to continue, it is important to have Galilei-covariant expressions for matrix elements of the energy-momentum tensor. In this work, I obtain Galilei-covariant breakdowns of such matrix elements into mechanical form factors, with a special focus on spin-half states. I additionally study the spatial densities associated with these form factors, using the pilot wave interpretation to guide their breakdown into contributions from internal structure and from quantum-mechanical effects such as wave packet dispersion. For completeness, I also obtain nonrelativistic Breit frame densities.

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Phys. Rev. D 112, 034037– Published 29 August, 2025
  • Received 30 June 2025
  • Accepted 11 August 2025
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