Pseudogauge ambiguity in the distributions of energy density, pressure, and shear force inside the nucleon

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Hauptverfasser: Fukushima, Kenji, Uji, Tomoya
Format: Preprint
Veröffentlicht: 2025
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author Fukushima, Kenji
Uji, Tomoya
author_facet Fukushima, Kenji
Uji, Tomoya
contents We study the spatial distributions of pressure, energy density, and shear forces inside the nucleon within the two-flavor Skyrme model including vector mesons. This framework has the advantage that nucleon configurations can be stabilized without the Skyrme term. In contrast to the model without vector mesons, however, we realize that the energy-momentum tensor (EMT) becomes pseudo-gauge dependent. We explicitly demonstrate that all these distributions differ between the canonical and Belinfante forms of the EMTs. We identify the pseudo-gauge ambiguity as originating from nonvanishing surface terms associated with spin currents generated by the vector-meson field strength tensors. Furthermore, we show that the pressure and shear-force distributions in the canonical EMT develop singularities at the nucleon center, whereas the corresponding Belinfante distributions remain finite. Finally, we discuss the implications of pseudo-gauge dependence for extracting the confining force and for constructing the equation of state inside the nucleon.
format Preprint
id arxiv_https___arxiv_org_abs_2509_10223
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Pseudogauge ambiguity in the distributions of energy density, pressure, and shear force inside the nucleon
Fukushima, Kenji
Uji, Tomoya
High Energy Physics - Phenomenology
Nuclear Theory
We study the spatial distributions of pressure, energy density, and shear forces inside the nucleon within the two-flavor Skyrme model including vector mesons. This framework has the advantage that nucleon configurations can be stabilized without the Skyrme term. In contrast to the model without vector mesons, however, we realize that the energy-momentum tensor (EMT) becomes pseudo-gauge dependent. We explicitly demonstrate that all these distributions differ between the canonical and Belinfante forms of the EMTs. We identify the pseudo-gauge ambiguity as originating from nonvanishing surface terms associated with spin currents generated by the vector-meson field strength tensors. Furthermore, we show that the pressure and shear-force distributions in the canonical EMT develop singularities at the nucleon center, whereas the corresponding Belinfante distributions remain finite. Finally, we discuss the implications of pseudo-gauge dependence for extracting the confining force and for constructing the equation of state inside the nucleon.
title Pseudogauge ambiguity in the distributions of energy density, pressure, and shear force inside the nucleon
topic High Energy Physics - Phenomenology
Nuclear Theory
url https://arxiv.org/abs/2509.10223