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Main Authors: Mulkey, T., Lopez, K. N., Hughes, C. D., Hill, B., Van Meter, M., Wijeratne, H., Long, J. C., Sarsour, M., Snow, W. M., Li, K., Parajuli, R., Samiei, S., Baxter, D. V., Luxnat, M., Zhang, Y., Jiang, C., Stringfellow, E., Torres, J., Hobbs, R.
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2508.14243
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author Mulkey, T.
Lopez, K. N.
Hughes, C. D.
Hill, B.
Van Meter, M.
Wijeratne, H.
Long, J. C.
Sarsour, M.
Snow, W. M.
Li, K.
Parajuli, R.
Samiei, S.
Baxter, D. V.
Luxnat, M.
Zhang, Y.
Jiang, C.
Stringfellow, E.
Torres, J.
Hobbs, R.
author_facet Mulkey, T.
Lopez, K. N.
Hughes, C. D.
Hill, B.
Van Meter, M.
Wijeratne, H.
Long, J. C.
Sarsour, M.
Snow, W. M.
Li, K.
Parajuli, R.
Samiei, S.
Baxter, D. V.
Luxnat, M.
Zhang, Y.
Jiang, C.
Stringfellow, E.
Torres, J.
Hobbs, R.
contents We report a search for exotic spin-spin interactions between neutrons and electrons which could signal new physics beyond the Standard Model using slow neutron polarimetric imaging through a dense medium of polarized electrons. Our dense polarized electron target is a ferrimagnet held at its magnetic compensation temperature, which realizes a polarized electron ensemble with zero net magnetization. We sought the spin rotation of transversely polarized neutrons from a neutron spin-electron spin interaction of the form $V_2=-g_A^eg_A^n\frac{\hbar c}{4π}\vecσ_e\cdot\vecσ_n\frac{e^{-r/λ_c}}{r}$, where $g_{A}^{e}$ and $g_{A}^{n}$ are the electron and neutron axial couplings, $\vec{σ_e}$ and $\vec{σ_n}$ are the electron and neutron spin, and $λ_c$ is the interaction range for an exotic axial vector interaction from massive spin-1 boson exchange of mass $\hbar c/λ_c$. The resulting average neutron spin rotation angle per unit length, $\frac{d\barϕ_{F5}}{dz}=[0.41\pm6.30\ (stat.)\pm4.4\ (sys.)]\times10^{-3}$ rad/m, is consistent with zero. Our novel approach improves the previous upper limits on the coupling constant product $g_A^eg_A^n$ by several orders of magnitude in the poorly explored $10^{-8}\leqλ_c\leq10^{-2}$ range.
format Preprint
id arxiv_https___arxiv_org_abs_2508_14243
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle New Upper Bounds on Exotic Neutron Spin-Electron Spin Interactions via Neutron Spin Rotation Measurements in a Compensated Ferrimagnet
Mulkey, T.
Lopez, K. N.
Hughes, C. D.
Hill, B.
Van Meter, M.
Wijeratne, H.
Long, J. C.
Sarsour, M.
Snow, W. M.
Li, K.
Parajuli, R.
Samiei, S.
Baxter, D. V.
Luxnat, M.
Zhang, Y.
Jiang, C.
Stringfellow, E.
Torres, J.
Hobbs, R.
Nuclear Experiment
Materials Science
High Energy Physics - Experiment
Quantum Physics
We report a search for exotic spin-spin interactions between neutrons and electrons which could signal new physics beyond the Standard Model using slow neutron polarimetric imaging through a dense medium of polarized electrons. Our dense polarized electron target is a ferrimagnet held at its magnetic compensation temperature, which realizes a polarized electron ensemble with zero net magnetization. We sought the spin rotation of transversely polarized neutrons from a neutron spin-electron spin interaction of the form $V_2=-g_A^eg_A^n\frac{\hbar c}{4π}\vecσ_e\cdot\vecσ_n\frac{e^{-r/λ_c}}{r}$, where $g_{A}^{e}$ and $g_{A}^{n}$ are the electron and neutron axial couplings, $\vec{σ_e}$ and $\vec{σ_n}$ are the electron and neutron spin, and $λ_c$ is the interaction range for an exotic axial vector interaction from massive spin-1 boson exchange of mass $\hbar c/λ_c$. The resulting average neutron spin rotation angle per unit length, $\frac{d\barϕ_{F5}}{dz}=[0.41\pm6.30\ (stat.)\pm4.4\ (sys.)]\times10^{-3}$ rad/m, is consistent with zero. Our novel approach improves the previous upper limits on the coupling constant product $g_A^eg_A^n$ by several orders of magnitude in the poorly explored $10^{-8}\leqλ_c\leq10^{-2}$ range.
title New Upper Bounds on Exotic Neutron Spin-Electron Spin Interactions via Neutron Spin Rotation Measurements in a Compensated Ferrimagnet
topic Nuclear Experiment
Materials Science
High Energy Physics - Experiment
Quantum Physics
url https://arxiv.org/abs/2508.14243