Quark Saturation in Magnetized Pure Neutron Matter
Abstract
We study how magnetic fields affect the onset of quark saturation, which limits the domain of applicability of a purely baryonic description. We consider matter composed of electrically neutral ddu baryons, including neutron- and Δ0-like states. Using a simple constituent-quark model, we compute the baryon wave functions and spectra in magnetic fields. The magnetic field polarizes the spin-flavor structure, compresses the internal wave function in the transverse direction, and strongly suppresses the transverse kinetic energy. From the baryon wave functions, we construct the one-body reduced density matrix and derive the corresponding single-quark distributions in longitudinal momentum and Landau-level space. We then use these distributions to evaluate quark occupation probabilities in an ideal baryon gas and determine the onset of quark saturation. At finite magnetic field in the +z-direction, the d↓ quark in the lowest Landau level reaches saturation first. The resulting saturation density depends nonmonotonically on the magnetic-field strength: it decreases at weak fields and increases at stronger fields. This behavior reflects the competition between spin-flavor polarization, which promotes saturation, and transverse spatial squeezing, which delays saturation by broadening of the quark transverse momentum distribution.
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BibTeX
@misc{kojo2026quark,
title = {{Quark Saturation in Magnetized Pure Neutron Matter}},
author = {Toru Kojo},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.36316},
eprint = {2610.36316},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.36316},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Quark Saturation in Magnetized Pure Neutron Matter
AU - Toru Kojo
PY - 2026
DA - 2026/10/26
PB - arXiv
DO - 10.48550/arxiv.2610.36316
UR - https://arxiv.org/abs/2610.36316
AB - We study how magnetic fields affect the onset of quark saturation, which limits the domain of applicability of a purely baryonic description. We consider matter composed of electrically neutral ddu baryons, including neutron- and Δ^0-like states. Using a simple constituent-quark model, we compute the baryon wave functions and spectra in magnetic fields. The magnetic field polarizes the spin-flavor structure, compresses the internal wave function in the transverse direction, and strongly suppresses the transverse kinetic energy. From the baryon wave functions, we construct the one-body reduced density matrix and derive the corresponding single-quark distributions in longitudinal momentum and Landau-level space. We then use these distributions to evaluate quark occupation probabilities in an ideal baryon gas and determine the onset of quark saturation. At finite magnetic field in the +z-direction, the d_↓ quark in the lowest Landau level reaches saturation first. The resulting saturation density depends nonmonotonically on the magnetic-field strength: it decreases at weak fields and increases at stronger fields. This behavior reflects the competition between spin-flavor polarization, which promotes saturation, and transverse spatial squeezing, which delays saturation by broadening of the quark transverse momentum distribution.
ER -