A Braak-Inspired Spectral Determinant Approach to a Dirac Bound-State Problem
Abstract
We develop a parity-resolved spectral-connection construction for a one-dimensional Dirac particle in an attractive soft-core Coulomb potential. The square-root dependence of the potential produces algebraic branch points in the coordinate plane. We uniformize these branch points by introducing t=√(x2+β2), while retaining the full-line Z2 symmetry generated by Π=σz Px. In each parity sector the resulting problem is formulated as a global connection problem between a solution selected at the physical origin and the decaying solution at infinity. This defines parity-resolved spectral connection functions whose zeros determine bound-state energies. We further construct a quasi-exact Bethe-ansatz sector directly from the same Dirac equations and use its polynomial solutions as independent benchmarks of the spectral condition. The comparison clarifies the distinction between local quasi-exact solvability and the global spectral determinant. The construction is inspired by the role of discrete symmetry and global analyticity in the quantum Rabi model, without identifying the present spectral function with Braak's G-function.
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BibTeX
@misc{zarrinkamar2026braakinspired,
title = {{A Braak-Inspired Spectral Determinant Approach to a Dirac Bound-State Problem}},
author = {Saber Zarrinkamar},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.10562},
eprint = {2610.10562},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.10562},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A Braak-Inspired Spectral Determinant Approach to a Dirac Bound-State Problem
AU - Saber Zarrinkamar
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2610.10562
UR - https://arxiv.org/abs/2610.10562
AB - We develop a parity-resolved spectral-connection construction for a one-dimensional Dirac particle in an attractive soft-core Coulomb potential. The square-root dependence of the potential produces algebraic branch points in the coordinate plane. We uniformize these branch points by introducing t=√(x^2+β^2), while retaining the full-line Z_2 symmetry generated by Π=σ_z P_x. In each parity sector the resulting problem is formulated as a global connection problem between a solution selected at the physical origin and the decaying solution at infinity. This defines parity-resolved spectral connection functions whose zeros determine bound-state energies. We further construct a quasi-exact Bethe-ansatz sector directly from the same Dirac equations and use its polynomial solutions as independent benchmarks of the spectral condition. The comparison clarifies the distinction between local quasi-exact solvability and the global spectral determinant. The construction is inspired by the role of discrete symmetry and global analyticity in the quantum Rabi model, without identifying the present spectral function with Braak's G-function.
ER -