First direct constraints on Fierz interference in free-neutron β decay

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Precision measurements of free-neutron β decay have been used to precisely constrain our understanding of the weak interaction. However, the neutron Fierz interference term bn, which is particularly sensitive to beyond-standard-model tensor currents at the TeV scale, has thus far eluded measurement. Here we report the first direct constraints on this term, finding bn=0.067±0.005stat-0.061+0.090sys, consistent with the standard model. The uncertainty is dominated by absolute energy reconstruction and the linearity of the β spectrometer energy response.

Original languageEnglish
Article number042501
JournalPhysical Review C
Issue number4
StatePublished - Oct 30 2017

Bibliographical note

Funding Information:
This work is supported in part by the US Department of Energy, Office of Nuclear Physics (DE-FG02-08ER41557, DE-SC0014622, DE-FG02-97ER41042) and the National Science Foundation (Grants No. NSF-0653222, No. NSF-0700491, No. NSF-0855538, No. NSF-1002814, No. NSF-1005233, No. NSF-1205977, No. NSF-1306997, No. NSF-1307426, No. 1506459, and No. NSF-1615153). We gratefully acknowledge the support of the LDRD program (20110043DR), and the LANSCE and AOT divisions of the Los Alamos National Laboratory.

Publisher Copyright:
© 2017 American Physical Society.

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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