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arXiv · 1911.01766

Limit on the Fierz Interference Term b from a Measurement of the Beta Asymmetry in Neutron Decay

Heiko Saul·Christoph Roick·Hartmut Abele·Holger Mest·Michael Klopf·Alexander Petukhov·Torsten Soldner·Xiangzun Wang·Dominik Werder·Bastian Märkisch
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Abstract

In the standard model of particle physics, the weak interaction is described by vector and axial-vector couplings only. Non-zero scalar or tensor interactions would imply an additional contribution to the differential decay rate of the neutron, the Fierz interference term. We derive a limit on this hypothetical term from a measurement using spin polarized neutrons. This method is statistically less sensitive than the determination from the spectral shape but features much cleaner systematics. We obtain a limit of b = 0.017(21) at 68.27 C.L., improving the previous best limit from neutron decay by a factor of four.

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Heiko Saul, Christoph Roick, Hartmut Abele, Holger Mest, Michael Klopf, Alexander Petukhov, Torsten Soldner, Xiangzun Wang, Dominik Werder, Bastian Märkisch. 2019-11-05. Limit on the Fierz Interference Term b from a Measurement of the Beta Asymmetry in Neutron Decay. https://doi.org/10.1103/physrevlett.125.112501

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