The Scalar MSW Effect: Compact analytical formulas for neutrino oscillations with large matter effects, including μ−μ and τ−τ dominant matter potentials
Abstract
Deriving simple and accurate three-flavor neutrino oscillation probability formulas in matter is critical for understanding the phenomenology of upcoming experiments. In this article, we extend the Jacobi diagonalization method for deriving effective parameter mappings for neutrino oscillations in matter. The key insight behind the extension is to purposefully parameterize the mixing matrix, UPMNS, using particular arrangements of Euler rotations. This novel extension allows for deriving simple and accurate effective mixing parameter mappings for exotic types of matter potentials. First, we revisit the Jacobi diagonalization method for neutrino oscillations with standard matter effects and use this to demonstrate our generalization. Subsequently, we apply the Jacobi diagonalization method to scalar non-standard interactions (SNSI) and derive effective parameter mappings for all three single diagonal coupling cases. The resulting formulas reveal that all diagonal SNSI couplings could give rise to a scalar MSW (SMSW) effect, that is an energy independent resonant enhancement analogous to the MSW effect. Finally, we study the accuracy of the derived SNSI formulas for various contemporary and upcoming experiments. For δmee, the accuracy is excellent for all considered experiments. For δmμμ and δmττ the accuracy is worse since ACC must be neglected, and first order perturbative corrections are applied to amend this.
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BibTeX
@misc{choubey2026scalar,
title = {{The Scalar MSW Effect: Compact analytical formulas for neutrino oscillations with large matter effects, including $μ-μ$ and $τ-τ$ dominant matter potentials}},
author = {Sandhya Choubey and Andreas Lund},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.02107},
eprint = {2610.02107},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.02107},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The Scalar MSW Effect: Compact analytical formulas for neutrino oscillations with large matter effects, including μ−μ and τ−τ dominant matter potentials
AU - Sandhya Choubey
AU - Andreas Lund
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2610.02107
UR - https://arxiv.org/abs/2610.02107
AB - Deriving simple and accurate three-flavor neutrino oscillation probability formulas in matter is critical for understanding the phenomenology of upcoming experiments. In this article, we extend the Jacobi diagonalization method for deriving effective parameter mappings for neutrino oscillations in matter. The key insight behind the extension is to purposefully parameterize the mixing matrix, U_PMNS, using particular arrangements of Euler rotations. This novel extension allows for deriving simple and accurate effective mixing parameter mappings for exotic types of matter potentials. First, we revisit the Jacobi diagonalization method for neutrino oscillations with standard matter effects and use this to demonstrate our generalization. Subsequently, we apply the Jacobi diagonalization method to scalar non-standard interactions (SNSI) and derive effective parameter mappings for all three single diagonal coupling cases. The resulting formulas reveal that all diagonal SNSI couplings could give rise to a scalar MSW (SMSW) effect, that is an energy independent resonant enhancement analogous to the MSW effect. Finally, we study the accuracy of the derived SNSI formulas for various contemporary and upcoming experiments. For δm_ee, the accuracy is excellent for all considered experiments. For δm_μμ and δm_ττ the accuracy is worse since A_CC must be neglected, and first order perturbative corrections are applied to amend this.
ER -